Collecting principal variations during search and using them in ordering?

In an Alpha Beta search in that utilizes a Negamax framework, how does one collect principal variations to use in move ordering

Every strong modern chess engine which uses alpha-beta search uses a transposition table to store the PV move for ordering. If you are writing a chess engine, you should this high-performance, now ubiquitous technique.

  and how does one use them, without using a transposition table?

There are various approaches to storing the principal variation which are commonly used alongside a transposition table. The most popular of these is a triangular PV table. The Chess Programming Wiki has a page on this, which includes code examples as you requested.

  Additionally, would it be different in a principal variation search

No. Move ordering can be implemented in the same way for both pure alpha-beta and for PVS. The only difference is the way in which the ordered moves are searched.

  and do we collect and store important moves for quiescence search too?

No. Standard techniques used to order captures are sufficient in quiescence search (namely, MVV/LVA and Static Exchange Evaluation). The move stored in the transposition table may not be a capture, so it is unlikely to be useful for quiescence.


After Bc4, is it better to play e6 to stop the bishop?

You have already mentioned one good thing about e6, it blocks the c4-bishop. It may not seem very important, but the white's attack on a2-g8 diagonal can be rather unpleasant later on, especially after white's moves f4 and e5.

Other important factor is the d5 square. Nd5 can be sometimes very unpleasant, so you want to avoid it. It potentially stops even Bd5 (for example after b5).

Black in these structure usually opts for a central break with d5 and e6 supports this plan. That's another reason for playing this move.

We shouldn't also forget the fact that e6 allows to develop the bishop on e7.

To the "weak" pawn on d6:

Here's the deal. You protected c5, d5, e5 and f5, you have avoided some nasty moves like Nd5 or Nf5, you have made some space for your bishop on f8... but there's a price for that. Your d-pawn has become a bit weak.

It's not such a problem, though. Bishop and queen is guarding that pawn and later you can even put a rook on the d-file. Also, as I said, d5 should be coming. That means the weak pawn won't be there forever.

I would say e6 has many more advantages than disadvantages... so I would go for it.


While the knight wouldn't be badly placed on f3, playing Ne2 keeps your f2-pawn unblocked, allowing you to push it up the board. If the pawn reaches f5 then you will have an overwhelming position. Also, on e2 the knight could go to g3, helping to control the f5-square while eyeing the h5-square.


Playing stockfish level 3000 on Arena 3.5.1

You need only one of the four engine files. The four executables are
compiles of the same source code for different CPUs. They differ in speed only; sorted in descending order these are: stockfish_8_x64_bmi2.exe, stockfish_8_x64_popcnt.exe, stockfish_8_x64.exe, stockfish_8_x32.exe. Keep the fastest which runs on your system and delete the other three.

  I loaded the four engines to Arena, but it always says at the top (2000), which  means level 2000, how do I make it level 3000+?

This number doesn't set the playing strength. It has informative purposes only. You can change it as follows:

Open 'Engine Management' (F11).
Click the 'Details' tab and select Stockfish from the list.
Click the 'Information' tab in the right part and type the desired value into the 'Rating' field. If this field is empty, a default value of 2000 will be used.
Close the dialog and start a new game to display your new setting.

You can't set Stockfish to play at a given Elo level. If you want to weaken it, change the Skill Level in the engine settings (Ctrl+1, if it's loaded as 1st engine). '0' is the weakest setting and the default value '20' means full strength.


Move first, record later; or vice-versa?

It hasn't always been so, but these days (at least according to FIDE rules) it's illegal to write your move down before making it, outside of some situations in which a draw is being claimed or the game is being adjourned. Here are the exact details as to when a move should be recorded (with the most relevant part italicized):

  8.1.
  In the course of play each player is required to record his own moves and those of his opponent in the correct manner, move after move, as clearly and legibily as possible, in the algebraic notation (See Appendix C), on the scoresheet prescribed for the competition.

  It is forbidden to write the moves in advance, unless the player is claiming a draw according to Article 9.2, or 9.3 or adjourning a game according to the Guidelines of Adjourned Games point 1.a.

  A player may reply to his opponent’s move before recording it, if he so wishes. He must record his previous move before making another.

I believe the reason that it's against the rules now is because writing the move in advance could be construed as some sort of analysis aid. (I'm not arguing that that's a good reason for the rule; it's just what I understand to be a rationale for the rule.)


What is a good defensive repertoire against a d4 opening?

The Queen's Gambit Declined. Get "Playing 1.d4 d5 - A Classical Repertoire by Nikolaos Ntirlis"


How can we teach this rule to a Beginner? (in a plain language or
  simplified way or associating any story to it)

The history gives the story.

At one time pawns could only move one square at a time even on the first move. But this made the game a bit slow. To speed it up the rule was changed to allow a pawn to move either one square, as before, or two squares on the first move.

But this changed the way one pawn could stop another pawn from moving because of the risk of capture. So, for instance, a black pawn on g4 stops a white pawn on h2 from moving. Before the rule change the only move the white pawn could make was from h2 to h3. Then the black pawn on g4 could capture it. After the rule change the black pawn could move straight from h2 to h4 thereby dodging the attack from the black pawn. This was unfair to the black pawn on g4 and changed the game in an unintended way. So, to even things up again the en passant rule was introduced which said that in that situation the g4 black pawn could take the h4 white pawn as if it had only moved one square.

The rule only applies on the move immediately after the double pawn move because with the old rule (only allowed to move one square on move one) if black didn't take immediately then white could move the pawn on his next move and the chance was gone.


How is the 2016 Zurich Chess Challenge "new classical" format different from rapid chess?

This is not different from rapid chess and will be rated only for the rapid Elo.

The name "new classical" is part of a push to shorten the classical time controls. Originally the idea was to have a time control with around 60 min per game, but in the end they decided to shorten it a little to make the games eligible for the rapid rating at least.


Could we assume that Gilberto Guerrero is actually Hernandez Guerrero,
  Gilberto?

We could but we would very likely be wrong.

First a word on how FIDE allocates FIDE numbers. FIDE doesn't allocate individual numbers to players. Instead it allocates ranges of numbers to individual federations.

Gilbert Guerrero's FIDE number is 2012707 and was allocated by the US federation.
Gilberto Hernandez Guerrero's FIDE number is 5100011 and was allocated by the Mexico federation.

For that to happen the same player would need to have registered with each federation resulting in one player with two FINs. Now that did happen in the early days and so is a possibility but is unlikely.

According to his Olimpbase records Gilbert Guerrero's only FIDE rated games were 12 games played in the second half of 1996 which gave him a rating of 2500.

Checking the Olimpbase data for 1997 for other players called Guerrero we see only one other, a Spanish player called Manuel Gomez Guerrero. He also has FIN 2207893, which is different from Gilberto Hernandez Guerrero, who has FIN 5100011, so not the same player.

The next step is to find, from Gilberto Hernandez Guerrero's FIDE profile what the details are for his earliest recorded result in FIDE's published data. To do that, in his profile, click on "Click to view All previous periods" under "Individual Calculations". There scroll to the bottom to see that there is an entry for July 2001. Clicking on that we see that the entry is for "Hernandez, Gilberto".

There are two possibilities here.

He changed his name some time since 2001
There are two players with different names but the Mexican federation re-used the FIN when one of the players died. By the way, the English Chess Federation did this with Tony Miles' FIN when he died! So, it can happen even with great players.

OK, back to the Olimpbase files to check on Hernandez, Gilberto. The Olimpbase records for this player go back to 1987 and the FIN is 5100011, the same as Gilberto Hernandez Guerrero.

Are Gilberto Hernandez Guerrero and Gilberto Hernandez the same player? Probably. They are the same federation. Maybe he did change or correct his name just before July 2006. The ratings match up before and after with no big jump. Furthermore it is very unlikely that a GM had a change of FIN like that in 2006.

Regarding the Campora game, here are his olimpbase records. He was 2543 in the July 1999 list and 2534 in the Jan 2000 list. Even playing blitz blindfold and drunk he would not have made those moves.

Apropos the reuse of Tony Miles' FIN. From his Olimpbase records you can see that his FIN was 403385. Today the player with that FIN is Andrew F Footner. Check his rating history and see that apparently he had results in the October 2001 list. Except the player listed is Tony Miles! There are no more results until January 2007 which are for Andrew F Footner.


What alternatives are there to Chess Position Trainer?

I like the online chesstempo beta opening manager and trainer.
I have read on the facebook page of chess position trainer, that chess position trainer 6 is coming this year. I aspect a lot from this software.

Lucas Chess has some interesting repertoire making functions. Like importing best moves or all best moves from a bin book, for one collar. You can export the openings to pgn but I have noticed that there is an error and there are many threefold and more-fold repetitions in the games. You can solve this by importing the pgn in chess position trainer and export to pgn again. I also like Hiarcs Chess explorer. You can sort games for one player by opening name. So you can make repertoires for it. You can edit the player name in a text editor or in Chess Assistant.


I remember reading about it in an old Chessbase Magazine edition (circa 2010 I believe). They examined a game where White played Bb5 at the right time, pinning the Knight then later exchanging it for weak queenside pawns, kinda like in the Ruy Lopez. I've used this idea fairly often, at least it's another option to Bc4, the normal development move that might later run into ...Be6 in this case, and it's not like exchanging and playing on the queenside is forced then.

If Black also develops their f8 Bishop, c3 and b4 also take space on the queenside, threatens b5 to kick the c6 Knight, and restrict both the Bishop and the Knight's activity.

In any case, there's nothing wrong with taking the center with 4.d4. As the f1 Bishop might want to go to b5 later, the first question to answer is how should the queenside be developed? c3 reinforces d4 and allows a Qb3-Bc4 battery, but Nc3 brings the Knight to a more active position (controls d5 in particular) than Nd2 where it would block the c1 Bishop. Take back the pawn with Bxf4 at some point (if ...g5, h4), and at this point, it should be clear where your light-squared Bishop can or should go.

At that point, White has completed development and has the center, whereas Black has trouble finding active play for his pieces. White should have a slight, lasting advantage, which should be converted in the long term. The rest is up to what themes you want to play around, but keep in mind the Bb5 idea.


Does the PGN specification mistakenly omit solidus (/) for symbol tokens?

You are right, the text as written there isn't exactly correct.

It also says that the marker is a symbol and lists * as one of the options, even though * is a token on its own and also cannot occur in a symbol.

That said, the meaning is clear enough, 1/2-1/2 is a valid termination marker. How you solve this in your code is up to you. As it's hard to add 1/2-1/2 as a token on its own (would need lookahead to disambiguate it from symbol 1 et cetera), it's probably easiest to add '/' to the possible symbol characters, yes.


This is a well known quote about pawns and tempi:

  A pawn is worth three tempi

So a pawn is worth 3 good, developing moves. Given that most games are 40 moves long then for bullet and blitz we have:

Bullet: 1 minute for all moves per side implies 1/40 minute per move, implying a pawn is worth 3/40' = 0.075' = 4.5''
Blitz: 5 minutes for all moves per side implies 5/40 minute per move, implying a pawn is worth 3*5/40' = 0.375' = 22.5''

This is a rough guide and the value of a pawn varies by position.


The game ended in a draw. Chessbomb isn't an official source, but it recorded the game as a draw, and the comments there indicate that the game was originally reported (by the digital board, perhaps) as a win for Black, but it has been corrected to a draw. These glitches happen from time to time.

As for the position: it doesn't seem possible for white to escape perpetual check, and black cannot force a mate and is far behind in material. Therefore, it's a draw.


There are chess sets made for the visually impaired.  They are called 'tactile' chess sets.  The game is played by touch. The pieces lock into the board.  Removing a lock constitutes "touch move".

Here's an example, though I am not sure it is a 'tournament quality' tactile set.


What is the correct name for a part of a chessboard: 'square' or 'cell'?

Yes, that's a "square". The word "cell" is never used. E.g. from the Wikipedia article:

  Chess is a two-player strategy board game played on a checkered board with 64 squares arranged in an 8×8 grid.

  The 64 squares alternate in color and are referred to as light and dark squares.

Or, if you prefer a dictionary:

  3 : any of the quadrilateral spaces marked out on a board for playing games

(source: Merriam-Webster)

  1.3 A small square area on the board used in a game.
  ‘move the white king's pawn forward two squares’

(source: Lexico, more example sentences about chess in that link)

Finally, as @chaosflaws notes in the comments, the official FIDE Laws of Chess:

  2.1 The chessboard is composed of an 8 x 8 grid of 64 equal squares alternately light (the ‘white’ squares) and dark (the ‘black’ squares).


What is the most effective openings to beat a 2200-2400 rated computer at chess?(With White and Black)

Wrong question.

If you want to beat a 2200-2400 opponent then you need to be a 2200-2400 level player.

The hippopotamus type openings are doomed to failure according to one old GM.  I find them very easy to beat but then  I do not usually play 2400 rated people.  OTOH they are not tactical type openings at all. Nor are they very aggressive.
If you want to play hardball tactics then play a more open type of opening.

You should master ONE basic opening and play that one.  It is not the opening that wins,  it is the player making the moves that wins or loses.

You should look at the French defense for black if you want to play that style.  For white try a Reti.  Or even just the Ruy.

A  Sicilian would be better but is much harder to learn.


I was not able to find an idea on how to generate long-term counterplay.
How can Black generate queenside counterplay that gives him equality?

It might be cruel for you but...answer is simple: in this position black can not achieve equality or counterplay at all. Your opening choice made you wait for him to kill you or if he's not able to (can't find as you said 'best moves'), then it might end in a draw. Scandinavian is not a good choice in case of counterplay.
Let's have a look at the position without using any engines:
White adventages:

Space
Pair of bishops
Pawn structure

Black has no pluses in this position at all. If you are standing worse you want to simplify the position by exchanging some pieces. However, looking at the black's pawn structure, it might be a bad idea to go for an endgame with doubled pawns which make the majority less effective and more vulnerable.
As you mentioned before, 12. ... - a5 might have been better than 12. ...-O-O. I would rather play a5 myself. Once he got to a5 square he might want to play a6 and create weakness n c6 making his Bg2 even stronger. And you can't really play a6 yourself leaving a nice hole on b6 and making b7 pawn vulnerable for rest of the game.
Another thing is, I don't understand why you'd like to play on a queenside when you are 3-4 in terms of pawns there. Any b-pawn or c-pawn move there makes his white-squared bishop a monster.
To sum up, I'm against that Scandinavian. Reason is simple: If there's a skill gap between you and your opponent, you end up in a (bit) worse, positional position, sooner or later you will get crushed. You have much better chances to play, as you called, sparta. There's better chance in complicated tactical positions against GM than playing against his positional (and overall chess) understanding and huge experience. Scandinavian is praying for a draw for me.


Can wildcard characters be used in search in Chessbase for Android?

From your own experimentation and the lack of documentation from a Google search indicates that wildcards are not supported at this time.


Where exactly in the Fide handbook can you find the hand shaking rule?

I'm not sure there was ever more than this press release.
It should have been expounded upon and turned into some rules of conduct, but it seems to me this never happened.

They do put the following rule in tournament regulations from time to time:

"13.3 The players shall shake hands (or shall greet each other in a normal social manner in accordance with the conventional rules of their society) before the start and after the end of each game. If a player fails to meet these requirements and after being asked to do so by the Chief Arbiter, then the player will lose the game immediately."

Which they really wouldn't have to do, if this rule was a part of the official laws of chess.


Theoretically, is the analysis of the moves more complex if the objective is to be the first to be checkmated?

Although selfmate is a popular type of chess problems, the concept you have described simply would not work in a chess game played from the starting position; your opponent would need to cooperate with you if you want to get yourself mated. This means that any game played by chess players of any skill level would almost certainly end in a draw under your rules, which unfortunately makes your question moot.


Nationality of the Azerbaijan Shakhriyar Mamedyarov and Teimour Radjabov

I have read a lot about them over the years, and I have never heard anything that would lead me to believe that they are anything but true Azerbaijanis, and have both played under that flag forever. Both were born in Azerbaijan while it was still part of the Soviet Union.

Speaking Russian is simply explained by the fact that since both born in Azerbaijan while it was still a republic of the Soviet Union, and no matter where you lived, or your ethnicity, Russian was the official language of the Soviet Union. You might have been bilingual, but you spoke Russian with the masses. I would imagine that even after the Soviet Union fell, they did not automatically switch away from that since it was so pervasive, and easy to talk to more people with.

I have never seen anything written about them being Jewish and the country has a demographic of 97.4% Muslim, 1.1% Christian, and 1.0% None, making that all the more unlikely.

I worked as a Russian translator from 1980-1988 while in the military.


List of famous, but incorrect, chess problems

You can find a list of 8039 cooked, which is the official term that means incorrect, chess problems here on the site Yet Another Chess Problem Database, often shortened to YACPDB. Another option is a list of 28670 problems on the Die Schwalbe Chess Problem Database that can be found by inputting 'COOKED' into the search bar.
A famous example of an incorrect problem is this problem, which calls for White to play and checkmate Black in 8 moves.
[Title "William Shinkman, St. Louis Globe-Democrat 1885, Mate In 8"]
[FEN "k7/P7/P7/P7/P7/P7/P7/R3K3 w - - 0 1"]

The intended solution was 1. 0-0-0!, White castling queenside, followed by 1... Kxa7 2. Rd8 Kxa6 3. Rd7 Kxa5 4. Rd6 Kxa4 5. Rd5 Kxa3 6. Rd4 Kxa2 7. Rd3 Ka1 8. Ra3#.
But as it turned out,, 1. Kd2! also checkmates on the 8th move, thereby making the problem incorrect. An example of a possible continuation is as follows: 1. Kd2 Kxa7 2. Re1 Kxa6 3. Re7 Kxa5 4. Re6 Kxa4 5. Re5 Kxa3 6. Kc3 Kxa2 7. Re1 Ka3 8. Ra1#.
On Tim Krabbe's website, there is an article entitled "The Kuwait Immortal, that is linked in Journal Entry #140.
Within, Krabbe published a correction of Shinkman's problem by Bader Al-Hajiri. The White king is now on g1, utilizing Chess960 to allow for a cook free long-range castling as the key.
[Title "Bader Al-Hajiri After William Shinkman), Tim Krabbe's Website  9/19/2007, dedicated to Tim Krabbe, Mate In 8 Under Chess 960"]
[FEN "k7/P7/P7/P7/P7/P7/P7/R5K1 w - - 0 1"]


HalfKP Structure for Stockfish / Shogi NNUE - how does it work?

[1]
Your understanding is correct, with one slight adjustment. Instead of thinking about it as "King on a1, Pawn on a2", you should think of it as two things: "King on a1, Friendly Pawn on a2", and "King on a1, Enemy Pawn on a2". The input layer knows the colors of the pieces. Note that I do not say White/Black, but Friendly/Enemy, which are relative. This is because the weights are the same for both sides, but flipped around and rotated a bit (depends on the engine)
[2]
Suppose we have a full board. All 32 pieces on the board. To compute the first layer of neurons (but not apply an activation), we will in essence perform 30 (we don't care about the king's directly) vector additions. You pointed out rightly that the inputs are 0s and 1s, so we use addition and not multiplication.
I now take a record of the values in each neuron (before activation). Now you make the move e2e4. You correctly point out that (for each side) two things change. Turn one bit off (King on X, Friendly Pawn on E2) and turn on (King on X, Friendly Pawn on E4). To update the remembered neurons, we only need to take the original values, subtract a vector of E2 pawn weights, and add a vector of E4 pawn weights. 31 additions (operations) now becomes 2.
[3]
As to your comments about using a simple input system. Your example is 768(=6x2x64) input bits. "Is piece A of colour B on square C". This works just fine. There is a chess engine named Halogen using this scheme, and I've trained networks for it. It is strong, but not as strong as the halfkp style networks. The theory is that the overspecialization allows for more knowledge, but without additional computation cost.
[4]
This one is a technical question, and it (in my view) relates to the first comment where the inputs are 0s and 1s, so really we use addition and not multiplication. Suppose you have two numbers, both of which are stored in 8-bits. If you multiply them, the result will need upto 16-bits to be represented.
Now consider the later layers of the network (ignoring the input for now). You take an 8-bit input, multiply by an 8-bit weight, sum a whole bunch of these up, and then output an 8-bit weight. In the intermediate steps you are dealing with 16-bit types, but later that information is packed down into 8-bits.
Multiple times I typed (before the activation) in my earlier answers. This is important. The intermediate data for computing the next layer of neurons is 16-bits. And since we are constantly adding and subtracting little pieces (from your e2e4 move), we are dealing with the intermediate data, and thus we want it available in 16 bits. For technical reasons, you might as well use 16-bits for the input weights, even though they are actually going to be within an 8-bit range. This is all subjective, and you or anyone else could use another scheme and be fine.
[5]
HalfKP allows us to reuse the same weights for both sides. Some engines will flip, some will rotate. For example, the weight for (White King on A1, White Pawn on A2) will be the same as the weight for (Black King on H1, Black Pawn on H2). This makes training much easier, as it "halves" the number of weights to be trained, which is akin to having more data.
Other solutions like HalfKA (accounts for the enemy King) are also viable, and are being used in an engine named Seer. The halfkp paradigm has some other ramifications to something called I call factorizorss, during training, but that is a much more complex discussion.
[6]
I'm not one for making big graphics, but I suppose "Yes" does answer your question :)
Source: I programmed all of this at one point https://github.com/AndyGrant/EtherealDev/tree/openbench_nnue/src/nnue which involved me going through each of your questions. I happen to have a different setup than Stockfish, but I considered the same issues and came to my own solutions while understanding the alternatives.


The path to mastering the openings isn't memorising moves and variations, it's understanding why certain moves are played in specific positions, why certain moves are favoured over others.
Memorisation is a shortcut to understanding, not a replacement. There are sharp offshoots of most opening systems that mean you have to be aware of certain traps and tactics, whether that be through understanding the position, memorising the move that avoids the trap, or calculating the tactics of each position.
System-based openings are less memory intensive, for example, the King's Indian Attack as White. There are certain theory lines that require some blend of memorisation/understanding/calculation, but most of the times the opening plays itself into a fairly standard set of middle-game positions.
The basics of openings is to occupy the centre, develop pieces towards that end. The next step of openings is to control the centre (not occupy), and develop pieces to either control the centre, or reduce your opponent's control of the centre (e.g. pins, exchanges, forced retreats). The King's Indian Defence is one of the latter sets of openings, of controlling the centre, not of occupying it, it is designed to let White dictate what centre he wants, and then for Black to undermine it. You want something more immediate, so you're looking for openings based on the classical view of the centre.
If you're looking for openings that more directly occupy the centre, then the Queen's Gambit Declined (or it's Slav relatives) is the most classical of openings to occupy the centre.
Basically meeting 1.e4 with 1... e5, and 1. d4 with 1... d5 will give you Black's best approach to occupy the centre directly, and directly contest White's attempt to occupy the centre.
I'd advise sticking to mainlines of major opening systems. They are mainline because they've been tested many times at highest levels and retain their soundness.


You should try to solve until you find the solution. If the puzzle is hard and has concepts new to you, it will take lots of time.

I remember that I tried to solve tactical puzzles for days, and eventually solved them. If you solve yourself, you can be sure that you understand the concept, that's very important. That is the thing what makes you progress. If you try to solve for a few minutes and then give up and check the answer, your time and the puzzle will be probably wasted.

If you think its too hard to solve in mind, you can set up a board and move the pieces. As long as you discover the solution yourself, your efforts will be rewarded.


1... Nxg4 works (?) because it allows Black to force a draw.

[FEN "r4rk1/pp1nbppp/2p1pn2/q6b/2B2BP1/2NP1N1P/PPP2P2/R2QR1K1 b - - 0 1"]

1... Nxg4 2.hxg4 Bxg4 3.Kg2 (3.Re3 Qh5 4.Kg2 e5 5.Bg3 Qh3+ 6.Kg1 b5 7.Bb3 a5 8.a4 Qh5) Qf5 4.Bg3 Bh3+ 5.Kg1 Bg4 6.Kg2

Now here's Stockfish's Bg6 variation. I think it's kinda whacked. White sacrifices a few pieces to achieve a perpetual check. It is instructional in that it shows that White can choose this outcome. It never would have occurred to me to even look for it. The 11. Ne5 variation within the diagram below shows that White doesn't have to settle for that draw; instead, the Knight move keeps the game going by ceding a meaningless -.08 advantage.

I think Bg6 is completely playable if Black is seeking more than a draw.

    [FEN "r4rk1/pp1nbppp/2p1pn2/q6b/2B2BP1/2NP1N1P/PPP2P2/R2QR1K1 b - - 0 1"]

    1... Bg6 2.Bb3 Nd5 3.Nxd5 cxd5 4.d4 h6 5.c3 Rac8 6.a4 Be4 7.Nd2 Bh7 8.Nf3 Nb6 9.Bc2 Bxc2 10.Qxc2 Nc4 11.Bxh6 (11. Ne5 Nxe5 12.Bxe5 Qd8 13.a5 Rc4 14.Bg3 Qd7 15.Kg2 b5 16.axb6 axb6 17.f4 b5 18.f5 b4 19.fxe6 fxe6 20.Rf1 Bf6 21.Qd3 Rfc8 22.Be1 e5 23.dxe5 Bxe5 24.Ra5 bxc3 25.bxc3 Bxc3 26.Bxc3 Rxc3 27.Qxd5+ Qxd5+ 28.Rxd5) gxh6 12.Rxe6 fxe6 13.Qg6+ Kh8 14.Qxh6+ Kg8 15.Qxe6+ Kh8 16.Qh6+ Kg8 17.Qe6+

It's 11:40pm here and it's racktime. If you have specific variations you want to see, let me know.

EDIT - ALNS has perhaps found a playable variation for White though it is not for the faint-hearted. White is down a pawn but has a passed center pawn.

[FEN "r4rk1/pp1nbppp/2p1pn2/q6b/2B2BP1/2NP1N1P/PPP2P2/R2QR1K1 b - - 0 1"]

1... Nxg4 2. hxg4 Bxg4 3. Re3 Qh5 4.Ne4 e5 5.Ng3 Qh3 6.Bxe5 Nxe5 7.Rxe5 Bh4 8.Qf1 Qxf1+ 9.Nxf1 Bxf3 10.Nh2 Bd5 11.Bxd5 Bf6 12.Rf5 cxd5 13.Rxd5 {with Stockfish rating Black slightly better.}


What are the things that a 2000 player knows that a 1800 player doesn't know?

Should I focus on opening?

Do you regularly fail to get out of the opening? Regularly get beaten whilst still in the opening? If yes then you definitely need to work on your openings.

Do you usually come out of the opening with a playable position? If yes then you are wasting your time spending more time working on openings if your goal is to improve.

Do you get a lot of pleasure working on openings? I know I do and that's why I still waste time on them even though I know my time would be better spent on other things.

Once you get to something like 2300 then openings start to become a lot more important. At that level and above games are much more often won and lost on superior opening preparation, often geared towards a particular opponent and his known opening repertoire.

Twice in the last 15 years I've prepared a specific opening for a specific opponent and they've gone along and played what I wanted / prepared. In both cases the resulting position was what the book told me was a much better position for me. In one game it certainly looked that way because even though I was playing somebody about 100 points stronger than me I went on to win.

In the second case I again reached a position which was supposed to be better for me but I couldn't really see what to do and went on and lost. When I put the second game through the computer it didn't think much of the "much better position for me". So, you can't always trust the opening books. The top players, of course, are writing those books. Are they still playing? Are they really going to give away their best moves? Or save them for the next time they play Kramnik or Carlsen?

Bottom line: the effort v reward equation isn't very good. What I've been doing recently on openings is just making sure I have a repertoire which gets me safely to the middle game where the real fight at my / our level begins.

Here's another question for you. Can you mate with KNB v K? If not then I would strongly recommend that you study this endgame until you can win 100% of the time against the computer.

Now I know what you are going to say. "But I've never, ever had that endgame and I'll probably die without ever seeing it in real life" That's true. But the point of learning that particular endgame is that rounding up, corralling and then mating the opponent's king with just a bishop and knight requires remarkable co-ordination between your three pieces. The important thing you gain from mastering this endgame is not the ability to mate with KBN v K but the ability to co-ordinate king, bishops and knights in the endgame and this will come up a lot.

I remember years ago being very pleased to reach what looked like an even endgame where we each had king, knight, bishop and several pawns against a much stronger player. I offered a draw, as you do. He was very polite and didn't burst out laughing. After he'd beaten me he explained. "Look", he said, "No disrespect, but you are a much weaker player. This kind of position is actually quite difficult. Of course it should be a draw but I know how to play it and you probably don't. So, of course I played on."

Now, I could have just given you the standard reply of "Study endgames" but that wouldn't have really helped because it is too general.

Now, go away and learn how to mate with KBN v K. Practice until you can beat the computer 100% of the time and you will get a lot more points. Not only will you start drawing games you would previously have lost and winning games you would have let slip away to a draw but you will also recognize earlier in the game how you can steer the game to the kinds of positions you know how to play well in the ending and avoid ones which are not so good.


The example below comes from Guy Haworth's Chess Endgame Records.

The annotations, as explained by Guy Haworth, are as follows:

% the only move available
! the only value-preserving move available (i.e., for a White move, the only winning move, and, for a Black move, the only drawing move, all others losing)
''' the only move which does not allow a repetition or otherwise waste time
''  the unique optimal move selected by the defined strategy
' an optimal but not unique optimal move

The other notation used is as follows (this is copied from Guy Haworth's book):

Metrics:
DTM Depth To Mate

Miscellaneous notation:
AUMS Absolutely Unique Move Sequence

[White "KR"]
[Black "KNP"]
[Result "1-0"]
[Date "2013.11.24"]
[Event "5m, 2-3m, KRKNP, GBR 0103.01, longest-known decisive AUMS: SV+M+/SUm"]
[Annotator "Haworth, Guy"]
[FEN "8/8/7p/7n/k7/8/2K5/3R4 w - - 0 1"]

1. Rd4+! {dtc/m/z = -26/-49/-17m} Ka3'' 2. Kd3! Kb3'' 3. Rd6! Kb4'' 4. Kd4! Nf4'' 5. Rb6+! Ka5'' 6. Rf6! Ne2+'' 7. Kc4! Ng3'' 8. Rg6! Ne4'' 9. Kd4! Nd2'' 10. Rg2! Nf3+'' 11. Kc5! Ka6'' 12. Rg6+! Kb7'' 13. Kd5! h5'' 14. Rh6! h4'' 15. Rf6! Ne1'' 16. Rf1! Nc2'' 17. Rb1+! Ka6'' 18. Rb2! Ne1'' 19. Ke4! h3'' 20. Rb1! Nc2' 21. Kd3! Na3'' 22. Ra1! h2' 23. Rxa3+! {KRKP: dtc/m/z = -3/-15/-3m} {Nalimov and Lomonosov DTM EGTs} *

Each of the first 35 plies, from White's 1st to White's 18th move, is the unique best for the player. What move is best for Black on their 18th turn depends on the criterion applied. Black's 18th move here, 18 ... Ne1, is the unique move which enables Black to maximise the number of successive White turns at which White has only one winning option. However, if Black is to maximise the number of future turns (i.e. maximise DTM), Ne1 is not best for Black: it loses for Black in 20; best is 18 ... Ne3+ (loses in 32) 19 Kc6 (best; wins in 32; Kc5 wins in 34).


Sufficient mating material, less a king?

Assuming opponent has no pieces:

4 or more knights
4 or more bishops, at least 2 per side
At least 2 pawns, but it also depends on where the pawns are
2 or more major pieces
Queen and a minor piece
Rook and 2 minor pieces
4 minor pieces
Pawn+Minor pieces/2 Minor Pieces(depending on where the pawn is or a major piece

If opponent have pieces:

Queen(maybe rook)+Minor Piece vs 1 pawn
Queen(maybe rook)+2 pawns vs Rook+Bishop+Pawn
Q+R vs Rook and bishop or 2 minor pieces(for most positions)


Play online live game against a friend with time odds?

On Lichess there is a button that allows you to give 15 seconds to your opponent. You could use it to just give a bunch of extra minutes to your friend at the start of a game.


Is there an engine evaluation technique that factors in 'time'?

Is there any established system for evaluating positions taking into account time for both players?

No, there isn't. This is for two main reasons:

There is no objective measure for how time affects a player's ability to play any given position.
Such evaluations would be useless. They would literally tell you nothing useful

Let me give an example from a game one of my clubmates (rated about 1800 at the time) played a few years ago in the UK National Universities Championships.
In the blitz section (3+2) in one of his games he reached a KBN vs K endgame with less than 30 seconds left on the clock. He knows that endgame (he has a strict coach who makes him learn that kind of stuff) and so blitzed out the win with plenty of time to spare on his clock.
I also have stronger clubmates (2100+), however, who don't know that endgame. They would never be able to mate in so little time. Give them 20 minutes on the clock and maybe they'd succeed. There have even been IMs who have failed with plenty of time on the clock.
Bottom line: even with as simple a position as this there is no way to provide a meaningful evaluation of the position that takes time into consideration.


Why is Bd6 better than Be7, Bc5 and Bb4?

Part of the problem with Bc5 is that they can respond with Na4, which threatens the bishop and grabs the tempo.  Be7 isn't great because its range is inhibited by the knight and it impedes the kingside rook's power on the e file after you castle. Bd6 is nice because it is protected by the pawns, the bishop can be retreated to b8 or c7 while still controlling either of the second longest diagonals.  I'm a 1500 rated player, so take that into account.


How do I create sharp, tactical positions?

There are two key principles:

Tactics can only flow from a superior position
Dissipating tension early is usually bad

What these tell us is that, first, it is important to follow sound general principles in the opening and early middlegame. So, develop your pieces, get your king safe and try and control the center. Developing tactics is going to be much more difficult if your pieces are not developed, your king is unsafe or you don't have control of the center.
Second, if every time your opponent makes a threat or offers an exchange of pawns or pieces you tamely exchange then it is going to be more difficult to generate tactics. Instead you should try and counter with threats of your own. Ignoring one threat and countering with a threat of your own will automatically increase the complexity of the position and make it more tactical.
There is a third important principle which materialists often struggle with and that is to view the values of the pawns and pieces not according to some fixed 1,3,5,9 system but according to what those pawns and pieces can do in regard of the current and possible future positions on the board.
Now for an example from the Closed Sicilian. In the Open Sicilian there is a tactical melee from the third move when white plays d4. There are captures and threats and lots of tactics. By contrast in the Closed Sicilian white avoids an early d4, there are no exchanges, open files or big tactical threats. It is all positional manoeuvering for control of the (closed) center.
[fen "r1bqk2r/pp2npbp/2npp1p1/2p5/2B1PP2/2NP1N2/PPP3PP/R1BQ1RK1 w - - 0 1"]

Here it is white to move. Both sides have almost completed development. Black has still to castle and both sides still need to develop their queenside bishops. The only capture threatened is BxN by black but that isn't going to happen. No way is black going to exchange their pride and joy, the Dragon bishop. The struggle for the center is intense. Black is currently threatening to play d5 and, as all Sicilian players know, if black can play d5 then they have equalized and, in the minds of most Sicilian players are already halfway to victory.
To continue the fight white must stop d5 and the best way of doing that is with Qe1 lining up the queen against the king and so pinning the knight against the king is the e pawns are exchanged after d5. Black castles renewing the threat of d5. Now white has no way of stopping d5. All white can do to stop black equalizing is to come up with a counter threat but what? There are no obvious threats white can make, no obvious tactics.
The answer is to offer a pawn sacrifice with f5. On the surface it looks like black can just win a pawn with the obvious exf5 (gxf5 looks much more dangerous) but this is turns out to be a losing blunder. Better is to plow on with d5 anyway and maybe even offer a counter pawn sacrifice. Play could continue:
[fen "r1bqk2r/pp2npbp/2npp1p1/2p5/2B1PP2/2NP1N2/PPP3PP/R1BQ1RK1 w - - 0 1"]

1. Qe1 O-O 2. f5 d5! (2...exf5? 3. Qh4! {and black is in trouble}) 3. Bb3 c4 4. dxc4 d4! 5. f6 Bxf6 6. e5

and what was a calm, positional struggle has suddenly exploded into a highly tactical game where lines are opening up, pieces are hanging and you better be able to calculate.


I know my mistakes but how would I learn from them?

Identify an error - you've done that.
Identify a better move - have you done that?
Find a memorable difference between 1 & 2.

Step 3 most often involves finding some sort of principle that the better move adheres to. "Exchange when ahead in material" for example. But this is an over simplification. There are different types of errors and they require different responses.

Some errors occur because we are tired or didn't have a good breakfast before the game. Others because we didn't see some tactic and only practicing tactics or chess problems will make significant inroads there.

Sometimes you make an error in the opening. When that happens; find example games where the correct move occurred. Play few a couple of them, find one you like, then memorise it. The whole thing. It's easier than you think and it really helps with opening study.

Strategic errors do seem to require reducing to principles. "I thought exchanging bishop for knight was ok but later I wasn't able to fight my opponents control on the light squares." This situation is difficult. Was the error the exchange or was it the way you played afterwards? Only studying strategy will allow you to judge. Once you make a judgement, trust in it, come up with a way to express why the move is better, some sort of principle that it exemplifies "bishops are stronger than knights if the center is open." And then see how you do.


Main Ideas behind Spanish Game, Cozio Defense

Indeed, 6...Nxd5 is not the main line. I remember some games with 6...Bg7 7.Bg5 h6 8.Bf6 Kf8, which is supposed to be a normal line, playable for Black.

In your game continuation, 8.Be2, keeping castling rights, looks good, e.g. 8...Ne5 9.0-0 Bg7 10.Re1 0-0 11.Nxd4 d6 12.f4 with a better development.


This is a special mark meaning diagram. When you export the game into a PDF/LaTeX file positions after moves marked with D are rendered in the document.

The only documentation I've found is https://sourceforge.net/p/scid/wiki/HowToExportGames/. Scid vs PC documentation maybe is clearer http://scidvspc.sourceforge.net/doc/Export.htm. But documentation is actually poor, I discovered this feature just testing the Export to LaTeX feature.


Does the Stockfish engine use past matches, or does it not need such a "database"?

Technically, Stockfish does make use of past matches, just not when it's playing. The way it uses its past matches is during training, when a new neural network (NNUE in Stockfish's case) is being trained. Once the NNUE is trained, though, it is "standalone" and does not change anymore.
The Stockfish you can download and play has an already-trained NNUE, so it does not use past matches.


Endgame tablebases are essentially databases containing known endgame positions that have been “solved”, so to speak. That is, every position in an endgame tablebase will have a corresponding result which will either be a win for white, a win for black, or a draw (assuming perfect play). They are used by chess engines because it is much more efficient for the computer to look up an endgame position in a database to get the result of the endgame rather than exhausting all the possible variations to determine the result.


In what cases is it good to play the Maroczy Bind in the Symmetrical English?

I have only ever played the Maroczy Bind against the sicilian and in the light of this limited knowledge all your propositions make some sense.

1./2. Be2 is where you normally place your bishop in the sicilian binds and it makes sense to refrain from e4 (at least for a time) if you fianchettoed the bishop. I have also read that after the fianchetto the square e4 is kept free for some possible piece maneuvers (Only Ne4 after d6 and e6 have been played comes to my mind).

3./4. The Maroczy is the main line against the acc. dragon, but not against the Paulsen/Kan. So one could deduce that the black bishop is better off on e7. But it is very playable against both and there is also the matter of move orders and the strength of alternative lines, so this probably doesn't make much of a difference.

In the end this is very much a question of concrete lines. There probably isn't an easy recipe for when to whip out the Maroczy Bind.


Is the Sicilian Defense a good opening for beginners?

The Sicilian is playable at all levels. 1.e4 e5 openings are easier to understand, so you will often see 1...e5 recommended for beginning and intermediate players (and I second that recommendation), but there's nothing wrong with 1...c5, and you should feel free to try it out and see if you like it.

To say how to play it correctly would take hundreds of pages. To answer your two specific questions:

After 1.e4 c5 2.Nf3, 2...e6 and 2...d6 are both perfectly good moves played at the highest levels.
The move ...a6 in the Sicilian has a few points, but the most important are that 1) it can keep a White knight away from b5, and 2) it can support ...b5 and start a queenside attack.


Can the King be attacked by a pinned piece?

Kd2 is indeed illegal. You can think of it this way: normally Black can't move his knight because White would "capture his king", but if White were able to play Kd2 then Black would capture White's king before White got a chance to capture his.


Real Chess Board which detects the moves we do

Yes, there are boards that record moves made automatically. This link should give you ample information about so called DGT-boards.

Because DGT-boards are pretty expensive, maybe you want to take a look at this discussion, in which the Novag Citrine board computer is proposed as a slightly cheaper alternative.

If the Novag is still too expensive, I would look further into the board computers/usb-boards, but those probably don't recognise the pieces automatically, which means they have to pressed on the starting and ending square of each move.


With only the King left, how can you get a draw?

If a player has a theoretical win, that person has a move limit (50 moves) with "no fundamental alteration of the position." That means no captures of pawns or pieces, and no pawn moves. The count is reset if either of these things happens.

There used to be an  exception for positions like king, bishop, and knight vs. King (a checkmate). It was known to be winnable in a maximum of 34 moves. But players got twice this maximum, or 68 moves (Milton Hanauer, "Chess Made Simple"). Apparently, this, and other exceptions, were removed later, according to a comment below.


Chess Pieces like classic 1997 "Pure Mate" ad

Try these themed sets from House of Staunton.  I don't see the set you're looking for, but you can expect whatever they have to be very high quality.  I love the Isle of Lewis set.

http://www.houseofstaunton.com/chess-pieces/themed-chess-pieces.html?src=feature


Strongest / most aggressive 1. d4 openings

I feel that the most ambitious, principled and aggressive 1.d4 repertoire is the one given by John Cox in his book "Starting Out: 1.d4!". Of course these are the most ambitious lines for white in chess so they have also got extreme amounts of published theory and as they lead to very sharp positions, not knowing the theory may lead to quick losses for white.

The main criticism of the book was that a collection of lines fit for top players may not be suitable for the audience of "Starting Out" books, but you don't ask for easy openings :-). Ironically even the world top has now moved away somewhat from these lines because the theory had been worked out so far, they go for slightly more restrained lines with g3 or so more of the time these days.

It is based on 1.d4 Nf6 2.c4 and 1.d4 d5 2.c4.

The following list of the lines it offers is from Watson's review of the book (http://theweekinchess.com/john-watson-reviews/the-end-of-openings-part-1), as I don't have the book with me right now:

  Cox's book suggests a complete repertoire for White beginning with 1
  d4. Here are a few of the main systems that he recommends:

  (a) versus the King's Indian: the main line 4 e4/5 Nf3/6 Be2/7 0-0 and 9 b4, the Bayonet Variation, , one of the most theoretical lines possible, with
  Black systems to cope with on every move that leads up to that move;

  (b) versus the Grünfeld: the main line of the 7 Nf3/8 Rb1 system, that
  is, the one that Edward Dearing recently wrote a densely-packed
  205-page book about;

  (c) versus the Nimzo-Indian: 4 Qc2 and pretty
  much every main-line line that follows this most investigated of
  modern lines;

  (d) versus the Benoni: the Modern Main Line with h3 and
  Bd3, again the most-analysed current variation;

  (e) versus the Benko
  Gambit: g3 and Bg2 with the contemporary main variation 10 Rb1;

  (f) versus the Queen's Gambit Declined: the main line Exchange Variation
  with the sharp Nge2;

  (g) versus the Tarrasch Defence, the main line: 6
  g3/9 Bg5, also ridden with traps and tricks to remember;

  (h) versus
  the Slav Defence: the main line with 6 Ne5, the most theoretical and
  complicated Slav line ;

  (i) versus the Semi-Slav: the main line
  Botvinnik Attack, one of the most-analysed variations in all of chess
  history.


Yes, there is a chess engine in Python: Sunfish
There is also a python library for chess: python-chess


To what extent (if at all) is the new Komodo 13 MCTS an AlphaZero Lite?

Komodo MCTS isn't a neural-network based engine. It just uses a different search algorithm, in particular MCTS instead of AB. Alphazero also used MCTS, so KMCTS is an "Alphazero lite" in that sense; however a distinguishing factor of Alphzero is that it uses a neural network to perform the evaluation, and KMCTS does not do that.

Is MCTS "better" than AB? Yes and no. From what I've seen, MCTS is exceptionally better when you want multiple PVs (because they effectively get it for free, while AB engines need to spend computational power). However MCTS loses firepower in tactical shoot-outs, and it's also really bad at winning a technical position. For example I remember seeing a KMCTS game in TCEC where its eval read "I have a forced checkmate" one move and then "wait, I don't, I only have a very large advantage" another, and then back to "I have a forced checkmate", etc.

Having said all that, KMCTS eliminated regular Komodo from the latest TCEC cup, so it's absolutely a respectable engine. In a straight-up game against another engine, it's not as strong as Stockfish or Leela, but it's comparable to everything else.


Why shouldn't the black king move to h7?

1...Kh7 leads to 2. Qxh6+! Kxh6 3. Rh3+ with mate in 2. If 2...Kg8, Black is mated with 3. Qxg6 Kh8 4. Rh1 with mate in 2.


The Karstedt fortress must be set up in a corner.
Even one square away it won't keep out the opposing King:

[Title "No fortress"]
[fen "6k1/5b2/7K/3nQ3/8/8/8/8 w - - 0 0"]

There is, however, a reverse fortress that keeps the stronger King
imprisoned:

[Title "Draw"]
[fen "8/8/8/8/8/5nkb/2Q5/7K w - - 0 0"]

and even a mutual Zugwzang involving this configuration:

[Title "Mutual Zugzwang!"]
[fen "8/8/8/8/4k3/5n1b/8/2Q4K w - - 0 0"]

1.Qh6 Bf1!
2.Qc1 Bh3!


Are you allowed to calculate on paper? e.g. corresponding squares? (FIDE/Club level etc)

This is never allowed in an actual, over-the-board tournament.

National chess federations ban analysis notes, and local chess organization follow their national rules for rating.


Why is g5 much better than gxh5 in this position of Anand?

With rook on g1, 13. gxh5 gives it a direct open file against the king.

Wrong! The black king is not on the g file. It is on the h file and the rook on f8 is ready, if required, to come to g8 and fight for the open file.

g5 allowed 13... Bg4, necessitating 14. Rxg4, an exchange sacrifice for the attack to continue.

Again, wrong. 13... Bg5 14 Rxg4 hxg4 really does open the file the black king is on, the h file. "allowed" is wrong and so is "necessitating". This sequence accelerates the attack. Without using an engine, 13... f5 looks to be better for black than Bg5, or at least less bad.

The fundamental idea of any pawn storm, such as that attempted by Anand, is to exchange pawns in front of the king.

Which is what happened in the game (white got rid of his h pawn, opening up the h file against the black king, and got rid of the black g pawn which was defending h5) with the bonus that white's g pawn was retained as a threat.

Why is 13. gxh5 so bad?

It blocks the h file (the file the black king is on) with a white pawn which white can't remove.


How do you copy PGN from the chess.com iPhone app?

Take up the menu in the bottom left corner of the completed game, press "share" and then "copy" and you should then be able to paste it wherever you want.


Perhaps you can use the table of contents from classical works such as

Modern Chess Strategy, by Pachman, and

The Middlegame, by Euwe and Kramer.


Which steps were blunders and inconsistencies?

Generally, black:

neglected development
weakened the light squares around the king

White should have opened the position with moves like d4 or even Nxe5 sometimes.

Opening the position is a standard theme in case your opponent neglects development and you can even sacrifice material to do so. This game is a good example of that.

It is worth it learning the common tactics that would have been possible at move 5 starting with Nxe5.

In summary you should take out of this game:

the theme with Nxe5, Qh5+ which is possible at several points
if a player neglects development, opening the position is almost always good

I annotated your game below. Have a look.

[FEN ""]

1. e4 e5 2. Nf3 d6 3. Bc4 f5? { too soon. Black should develop some pieces first } 4. Nc3!? { Ok-ish, but white could take advantage of black's underdevelopment by opening the position with d4. } (4. d4 fxe4 { not the best move, but in any case white will open the position and have a clear advantage because of development. } 5. Nxe5! { Making use of a well known tactics which can often be used against opponents playing an early f4 or f5. } 5... dxe5 6. Qh5+ g6 7. Qxe5+ { winning the rook }) 4... f4 { Why? Development was asked for! } (4... Nf6)  (4... fxe4 5. Nxe5 dxe5 6. Qh5+ g6 (6... Ke7 7. Qxe5+ Kd7 8. Qe6#)  (6... Kd7 7. Qf5+ Kc6 8. Qxe4+ { and a very strong attack }) 7. Qxe5+ { winning the rook }) 5. O-O { From a positional point of view this is questionable because white is basically castling into the attack / pawn storm of black. Might consider long castle instead. In any case the same tactics as before also works here (basically if somebody plays e5 and f5 and the f pawn is not anymore on f5 this tactics is always an option. Of course also works for reversed colors with e4, f4) } (5. Nxe5 dxe5 6. Qh5+ g6 (6... Ke7 7. Qxe5+ Kd7 8. Qe6#)  (6... Kd7 7. d4 { and a very strong attack }) 7. Qxe5+ { winning the rook }) 5... g5?? { Looks very dangerous because without the knight on f3, Qh5+ looks terrible for black. } 6. d3 { too timid. Yet again white should open the position with d4. The computer says that white can even give a knight in order to take advantage of the open position. } (6. d4 g4 7. dxe5! gxf3 8. Qxf3 { and white is clearly better as black cannot defend against all the checks along the light colored diagonals. }) 6... g4 7. Ne1 Nc6 8. h3? { Playing for tricks (which worked). However objectively this is an awful move to make. Generally defending against a pawn storm is easier if the pawns remain on one line. By playing h3 white is voluntarily opening the position around the castled king (not immediately but soon), which is very dangerous. This is even true if there was no black pawn on g4 yet. } (8. d4! { Not obvious move, but works because of tactics. Notice how much space white suddenly gets: The knight can go to d3, the bishop has potential to f4... For a good player this is a common theme: Open the position if your opponent is not developed. } 8... Nxd4 (8... exd4 9. Nd5 { and white will get the d4 pawn and is better because of better development }) 9. Bxf4 { and white is better }) 8... gxh3?? { Final mistake. It is a forced mate in 3 now. } (8... h5 { And black is clearly better. White's position is very cramped and the king in danger of attack with ideas like Qh4... })  (8... Nf6 { Should also be much better for black, because white cannot free himself and the king will be under attack soon. }) 9. Qh5+ Kd7 10. Qf5+ Ke8 11. Bf7+ { There was a mate in one. } (11. Qf7#) 11... Ke7 12. Nd5# *


You're looking for a chess engine. A engine can give you the evaluation of the position - a value that relays whether white or black has the advantage. A positive evaluation means white is better - with a greater number indicating a larger advantage - and vice versa.

As for the online resource, there are many options available to you. I would recommend downloading a free graphical user interface client such as XBoard to be used in conjunction with a strong engine, such as Houdini (the free version).

To input the position of your son's game, you can either copy and paste the FEN of the position or the current PGN of the game. The former contains information regarding the position and the latter has the notation of all the moves up to the current position. From there, running the engine will return the evaluation.

There are many tutorials online on how to set up the chess software - here is one example specific to XBoard and Houdini.


Custom icons/designs for online with other people?

Hi Anon and welcome to chess.stackexchange.
I would begin at Peter Wong's virtual pieces site. Have a look at this, and if necessary contact Peter, who is very friendly and approachable.
All the best.


That's known as "D20 Queen's Gambit Accepted, 3.e4"

The Queen's Gambit has two points:

Develop the King's Bishop with tempo
Take the center that black abandons

in that regard, 3. e4 is the better move though masters play 3. e3 with nearly the same frequency.

I wouldn't worry about the loss of the c pawn;  the purpose of a gambit is to gain time.  If you're going to offer a gambit, you must know enough to keep the pressure on, to keep the initiative on your side.  If White plays a non-threatening move and Black plays a move with good purpose, White has lost the pawn as well as the time gained when Black took it.

3... b5 is not played often - it's not much of a move.  I checked your entire variation; it was only occurred in my masters database 3 times, yielding White 2.5 points.

Here's a master game demonstrating the Queens Gambit Accepted (D20).  White has an excellent game up through the middle game seemingly having the game in hand... and then he allows Black to make a passed pawn, and the walls came down.

Robert Aghasaryan vs. Tigran Kotanjian, 1/13/2013

[fen ""]
1. d4 d5 2. c4 dxc4 3. Nf3 Nf6 4. e3 e6 5. Bxc4 c5 6. O-O a6 7. dxc5 Qxd1 8. Rxd1 Bxc5 9. Nbd2 b6 10. Be2 Bb7 11. Nc4 Nbd7 12. a3 O-O 13. b4 Be7 14. Bb2 Bd5 15. Nfe5 Nxe5 16. Bxe5 Bxc4 17. Bxc4 a5 18. b5 Rac8 19. Be2 Nd5 20. Bf3 Nc3 21. Rd7 Bf6 22. Bxf6 gxf6 23. Rd6 Rb8 24. a4 Rfc8 25. Rd4 f5 26. Kf1 e5 27. Rd7 Rc4 28. Rc1 Rc5 29. Bh5 Nxa4 30. Bxf7+ Kh8 31. Rxc5 Nxc5 32. Re7 Rb7 33. Re8+ Kg7 34. Bd5 Rd7 35. Rxe5 Kf6 36. f4 a4 37. Ke2 a3 38. Bc4 Ra7 39. Ba2 Ra5 40. Kd2 Rxb5 41. Kc3 Ne4+ 42. Kd4 Rb4+ 43. Kd3 Rb2 44. Re6+ Kg7 0-1

Here's a game where black played b5. Ruslan Ponomariov vs. Ivan Sokolov, 3/17/2007

[fen ""]
1.  d4  d5
2.  c4  dxc4
3.  e4  b5
4.  a4  c6
5.  axb5    cxb5
6.  Nc3 Bd7
7.  Nf3 e6
8.  Be2 Nf6
9.  O-O Be7
10. d5  exd5
11. exd5    Qb6
12. Bf4 Bc5
13. Bxc4    bxc4
14. Qe2+    Kf8
15. Ne5 Bf5
16. Na4 Qb5
17. Nxc5    Qxc5
18. Nxc4    Qd4
19. Be5 Bd3
20. Qd2 Qxd5
21. Rfd1    Qxc4
22. Rac1    Qa6
23. Bxf6    Nd7 (23... gxf6?! 24.Qh6+ Ke7 25.Qe3+ Qe6 26.Qxd3 Nd7 27.Qa3+ Ke8 28.Qa4 Kf8 29.Rxd7 Kg7 30.h3 Rhd8 31.Rxd8 Rxd8 32.Qxa7 Qe2 33.Qb6 Rd2 34.b4 h5 35.Qc5 Rb2 36.Qd4 Qe5 37.Qc4 Qb8 38.Qh4 Qxb4 39.Qxh5)
24. Bc3 Bb5
25. Qg5 Nf6
26. Qc5+    Kg8
27. Bxf6    h6
28. Bc3 Re8
29. Rd6 Qb7
30. Qf5 Qe7
31. Qxb5     1-0

After Black's 6th move, it looks like maybe he'll be able to shove those pawns forward, overpower White's Queen's Knight pawn, and win. Sometimes, advanced pawns are not easy to support.  By the end of move 11, both players have developed some pieces but neither side is pushing very hard.  Black's Queen on b6 eyes the perpetually weak f2 square and the King hiding beyond while threatening, perhaps, b4.  White's 14th exploits Black's uncastled King. Black's response seals in the Rook.

After 17, both Black rooks and a knight are in the box.  His King is exposed.  He has a good bishop and Knight and his Queen is well placed.  His c pawn looks lonely and has to be defended by the Queen.  White has a great Knight and a good Bishop.  His isolated b pawn is sad but not endangered.  His d pawn is kinda hanging out. One of his Rooks is sort of developed and the other has good squares.  But White has sacrificed a piece and needs to make something happen.

After  move 24, White maintains a slight lead, even though he's down a piece. Black needs to activate his rooks to win.  White must not allow this.  This is where every tempo counts.  White's 25th hits the weak g7 pawn while his 26th exploits Black's exposed King.  White's follow-up, 27. Bxf6 exploits the overloaded Black Queen.  It protects the Bishop as well as the Knight since the last thing Black needs is for his pawns to be ripped open with Rooks on the board.  if 27... gxf6 then 28. Rc3 followed by Rg3+ and it's lights-out for Black.  White saves his Bishop but the cost is that Black now has time to develop a Rook to e8.  The end of the game isn't spectacular, it looks like Black blundered in time pressure.


What are the main differences between 6...Bb4 and 6...Be7 in the Panov-Botvinnik attack?

According to the Game Database of ChessTempo, the mainlines of 6...Bb4 and 6....Be7 are quite similar:

6....Be7 7.cxd5 Nxd5 8.Bd3 Nc6 9.0-0
6....Bb4 7.cxd5 Nxd5 8.Bd2 Nc6 9.Bd3 0-0 10.0-0

Remarkably, the main move for the second line is 10....Be7, which transposes to the first line, but with an extra Bd2 for white. For instance, Nakamura-Wojtaszek and Motylev-Jakovenko.

Instead of 7.cxd5, white can also play 7.Bd3. In this case it is difficult to tell whether the bishop is better placed on b4 (to have the possibility to take on c3) or on e7 (to protect against the pin after Bg5).

Edit by Evargalo: The logic behind Black wanting the White bishop on d2 and not c1 is a bit complicated: In the variations with the bishop on c1, the main line (after 9.0-0 Nc6) is the logical 10.Re1, where there is a lot of theory and Black has to work hard to equalize. With the bishop on d2, however, 11.Re1?! is a dubious pawn sacrifice after 11...Ndb4! 12. Bb1 (or Be4, or Bf1, or Bc4) Nxd4, because the Bd2 interferes in the Qd1-Pd4 connection. Thus the main lines are 11.Qe2 or 11.a3, which are less direct although the opening debate remains open to this day.

Objectively speaking, the values of 6....Bb4 and 6....Be7 are probably similar. Therefore, choosing between both moves is more a matter of taste.

Note that the position after 6....Bb4 can also arise after a transposition from the Nimzo-Indian, which is the subject of another Stack Exchange question.

      [StartPly "11"]

      [FEN ""]
      1.e4 c6 2.d4 d5 3.exd5 cxd5 4.c4 Nf6 5.Nc3 e6 6.Nf3 Bb4 (6...Be7 7.cxd5 (7.Bd3) Nxd5 8.Bd3 O-O 9.O-O Nc6 10.Re1) 7.cxd5 (7.Bd3) Nxd5 8.Bd2 Nc6 9.Bd3 O-O 10.O-O Be7 11.Re1?! (11.Qe2) (11.a3) Ndb4 12.Be4 Nxd4


That's the definition of a "stalemate", which is a draw, i.e. if it's your turn to move and your lone king has no legal move.  It can also happen in other situations, such as for example if you also have blocked pawns on the board in addition to the king, since you will still have no legal move. This is often the last resort of the novice, the hope that his opponent will let him obtain such a position. If you are the player with the rook and queen, or even just a queen, in such a situation, you must be careful to always leave your opponent's king a space to move to if you don't have an immediate mate to avoid this occurring.  Of course, it's much less likely that you can get a stalemate against a more skilled opponent, although some strong players have "swindled" their equally strong opponents out of a win thereby, one famous case being a long-ago game between Grandmasters Larry Evans and Samuel Reshevsky.


What is a good chess engine to play against on an android phone?

Droidfish app on Android is what you need. It has professional level GUI(with sophisticated analysis functions) with Stockfish engine pre-installed.


What do you need in order to organize a chess tournament?

A few things should come first, others can come later.

One, what type of event do you want to run? Several of the later questions depend on how formal the event is going to be, and people need to know what kind of an event it will be before they know whether they want to come at all. You have zero experience and mention the word casual, so we'll go for very casual, fun, not formal at all.

Two, how many people can you reasonably expect? You need to know a minimum number (if fewer than this number of people have registered a week before the tournament, we'll need to cancel), and a maximum (we can't accommodate more than this number of people). This ties in with important question three.

Three, how long do you want it to take. Will this be a whole day tournament, only an evening? Are you thinking of blitz, or rapid, or standard? If it's standard, you can only fit one or two games into an evening, but a whole blitz tournament easily goes. The time control that most says "fun and casual" to me is 10 minutes per game.

Four, the venue. This differs by type of event (we're casual), and before you start looking for one you need to know roughly what size you want, and after you've arranged it, this decides the min and max people. You'll also need a very different venue if you want it for one day or for the evening. I would definitely contact the local chess club, because hey, they're the local chess club! They might even enjoy helping you out with all this stuff for fun (in my country anyway, these are purely amateur organizations doing chess stuff as a hobby). Other than that, when I think casual chess tournament with people I know from the Internet, I think lots of beer. Look for tables in local bars, or event rooms at local bars, that sort of thing.

You'll also have a date by now.

So now you can tell people, "We're doing a fun and casual, 10 minute / game rapid tournament, unrated, time X on date Y in venue Z. Please register if you want to come!"
No, wait, you can't -- you don't know yet how much it's going to cost!

Let's talk a little bit about systems. Formal competitive chess tournaments often apply the Swiss System. It's very fair, you play against people who have the same number of points as you have, you get more or less equal numbers of black and white, and often the best players wins. It's a nightmare to run correctly, mainly because you have to get all the results after each round, enter them all correctly into the computer (or do it by hand, let's not) and then print out new pairings and find out something has always gone wrong. And even if it goes perfectly, people have to wait until the last game of the round is finished all the time.

Let the players do the work. For groups up to around 10 players or so where everybody plays everybody, there are "Berger tables" with pairings for each round: http://www.tournamentdirector.co.uk/berger_pairings.html . Show the players the pairings table, and let them fill in the results on a form you have printed out beforehand. No work for you during the tournaments.

If you have too many players (too many rounds for the time you have the venue), there's the Amsterdam System: first put players in small groups, of 4 or 6 people. Make one player the leader of that group, and give him a form for it. Let them play a little subtournament. When all subtournaments are done, make a ranking of all the players based on the points they got, then make new groups based on that. A finals group with all the best players, second group with the second best, etc. The key is that during most of the tournaments, the players are doing the administration and it all goes a lot faster.

Oh yes, your questions:

Chessboards: You're not going to become a chess club, are you? Try to borrow some from the chess club, and otherwise let people bring their own. Let them bring clocks, too! White player has choice of set.

Buying score sheets: Not necessary in an informal rapid tournament.

Dividing into groups: Not necessary in an informal rapid tournament (and in the Amsterdam System, they end up in the right group soon enough anyway).

Location: mentioned some things already.

Trophies: More is always better. Prizes can be silly things, I've won Tupperware stuff at great chess tournaments. Bottles of wine always work well as top prizes, but the golden rule is that more than half the people should go home with at least a tiny something. Besides the obvious best junior, best female, best organizer, prize for the guy who came last, prize for the guy who came second to last and expected he didn't have to come up and collect a prize, player whose performance was least noticeable, etc etc. Prize givings like these are great memories for everyone, and any other kind is instantly forgotten. And don't do money prizes, you're a casual tournament.

Play yourself: You can, but you better have everything for pairings and results exactly planned out, and it's going to be hectic. Playing arbiters: formal arbiters aren't necessary in a purely informal tournament without money prizes, but if there are any actual arbiters or very experienced players in your group, that's very helpful to know. Make them the Committee of Appeal and let them handle people who argue.

And now I need to sleep. HTH.

(I still don't know about the cost. It's venue + prizes / number of players, but if the venue cost is fixed and you don't know the number of players, you have to fiddle it to prevent too much risk for yourself)

(Addendum: and don't do this alone. Some assistants when it gets all hectic are needed)


Do I have to follow the openings moves when the response is different?

You never "have" to follow an opening sequence, especially just for the sake of following an opening name. There's nothing special about the "Danish Gambit"; it's just a group of moves someone decided to give a name. Any sequence of moves can be given a name if people really wanted.  If your opponent plays a different move order or unexpected move you should adjust your play accordingly. But of course there's always a chance you might transpose back into that "Danish Gambit" line depending on what moves are played.


What are some of the best sites to play chess?

Chess.com has become a hot spot, with live and correspondence chess, along with tactical problems, articles, etc.  The live chess is OK, but not the best.

ICC or playchess are the best for live chess, FICS if you want free, but it doesn't have as many titled players or features.  Those sites will also have video's, live commentary of top level tournaments, and much more.


Well, they don't have an explicit protocol on whether to use the first name, the last name, or both the first and last name. Though admittedly, the Lange Attack sounds more right than the Max Lange attack.

There is a completely different story for how an opening gets its name. There are a couple openings that are named after people that didn't even play the opening or come up with the opening itself. Furthermore, there are openings named after animals or whatever; the Sicilian dragon, the Halloween gambit, the English opening, the French defense, the Hedgehog, the King's gambit, etc.

It might be based on the individual. They try to come up with a formal name of a variation based on the person's name, but to some people, it is more formal to use only the last name or the other way around (Grandmaster Tarjan instead of Grandmaster James or Grandmaster James Tarjan). On top of that, if you are lesser known or not famous, then it is considered more formal to use both the first and last name.

You have the Ruy Lopez, but not many other openings that use the first name. It is likely a result of the guy's preference. Again, an individual story for every opening, and it is cultural and normal to use only the last name, but there is ought to be a line that uses the first and last name too.


Is three knights versus knight really winning?

It is lost. You can enter all positions of six pieces into a tablebase, like this online one.

It's mate in at most 39 moves, for example:

[FEN "4N1K1/5P2/6k1/8/6n1/8/N7/8 w - - 0 1"]

1.f8=N+ Kf5 2.Kg7 Ke4 3.Nb4 Kd4 4.Kf7 Kc5 5.Na6 Kd4 6.Nac7 Ne5 7.Kf6 Nc4 8.Ke6 Na5 9.Nd6 Nc4 10.Nf5 Kd3 11.Nd5 Na5 12.Nf6 Nc4 13.N8d7 Kd2 14.Nd5 Ke2 15.Kf6 Kd2 16.Nc5 Kc2 17.Nd4 Kd2 18.Kg5 Na5 19.Kf5 Nc4 20.Ke4 Kd1 21.Kd3 Ne5 22.Kc3 Ke1 23.Ne4 Ng6 24.Kc2 Ne5 25.Nf4 Nc4 26.Kc3 Ne5 27.Nf5 Kf1 28.Kc2 Nc4 29.Nfg3 Kg1 30.Kd3 Na5 31.Ke2 Nc6 32.Nf5 Ne5 33.Nd2 Kh1 34.Kf2 Ng4 35.Kg3 Nh6 36.Nxh6 Kg1 37.Ng4 Kh1 38.Nf2 Kg1 39.Ne2#.

There were many other choices along the way for both sides that would lead to the same amount of moves.

Edit: I think this is probably a quite modern study, where the composer used tablebases in the process of composing the study, but I might be wrong.


What is the benefit of making the first move with a Knight?

It's not worth it to analyze 1st moves with an engine. It's better to see possible variations in ChessBase's ECO view because you need to play opening which suits your mind style or antisuits your opponent's. An engine can't help you with that.


What makes a contemporary chess problem decent?

One might simply look at the judging metrics at the World Chess Composition Tournament (WCCT) to derive such an answer.

This is from their Rules Annex and details how points are allocated to a composition entry. I've stressed key words that probably represent a figure of merit.

  Points : Description

  4.0 : An outstanding problem: an accurate and intensive rendering of the set theme, without blemishes in any of the main lines, and showing
  originality and flair. Perfect construction and economy.

  3.5 : As above, but some small constructional weaknesses, and perhaps not ideally economical.

  3.0 : Either: a very good problem showing the theme clearly but perhaps not intensively or very originally Or: a task rendering of the theme
  which does not reach the highest artistic standard. In either case,
  good construction and economy.

  2.5 : As above, but constructional weakness and/or less than ideal economy because of the intensive or task setting.

  2.0 : A good problem, very likely worth an honourable mention or commendation in a reasonably strong tourney, but not a very intensive
  rendering of the theme, and perhaps not very original. Adequate to
  good construction and economy.

  1.5 : As above, but with some artistic weakness or constructional blemish.

  1.0 : A very ordinary piece of work, typical of many average columns but hardly up to award standard. Adequate construction and economy.

  0.5 : As above, but with serious constructional defects.

  0.0 : Unsound, unthematic or fully anticipated.


What is the theoretical limit for the number of consecutive checks?

Another way to get an infinite series of checks is by using a fairy piece. Consider this position, except that the black piece on e5 is not a knight but a camel (a (3,1)-leaper). Then the given sequence of four crosschecks restores the diagram position with White to move. (Unfortunately the PGN-viewer can't display it because of the fairy piece.)

[Title "Infinite series of checks"]
[fen "1k1b4/8/8/KN2n1r1/8/6B1/8/1R6 w - - 0 1"]
[StartFlipped "0"]

1. Nc7+ Cb6+ 2. Nb5+ Ce5+


Developing the king before developing most of your pieces

Don't try this at home. ;-)

First of all, a simple LiChess search gives this is B12 Caro-Kann Defense: Advance Variation, Tal Variation, i.e. it has even a name and is legit.
Second, 8 games listed, with IMs playing it, so it's still rare.
Third, standard Black move is Kb8. He doesn't even try to immediately throw everything except the kitchen sink at the white king!
And that is because the king is rather safe there. Usually you now would try the can opener g6 or f6, but it's not so easy as the king side of Black is underdeveloped and White can keep the relevant files closed. Black can't simply pile up major force, and already Steinitz said you need a force plus to storm the defense.
This is caused by the large space advantage of White at the kingside.
A concrete advantage of wK on g3 is that it does something useful (protecting g4) and avoids something annoying (tactics on e1, pins on g1...).
Note that the center is totally barricaded, otherwise it would be suicide.
Summing up, yes, in this concrete position (modern chess is hyperconcrete) it might be a good idea.

Concerning your last question (are there other variants?), this could be easily answered by a search in a Megabase. Steinitz Gambit of course comes to mind immediately.


What are the common mistakes make by chess engines at ELO range 1500 - 1800?

I'm also a chess engine developer, let me answer you from my own experience:

There're lot of reasons differentiate the playing ability. Actually, a lot. This is an area where one could write a PhD thesis, but let's take a quick look at the two major factors.

Ability to do a cutoff quicker
Ability to evaluate a position better

Unlike a human player, a computer chess algorithm doesn't need a sophisticated position evaluation. Lots of weak engines tend to use some very complicated evaluations, such as cubic interpolation of material values but none have been proven to work. Simple is the key. Stockfish, the strongest engine in the world, has an evaluation about Elo 1800. It might sound amazing that an Elo 3000+ engine has a simple evaluation that is only about Elo 1800 level. But remember, a computer needs to use this evaluation function for hundreds of thousands of positions. The simpler, the faster the engine can search, the higher depth it can reach and therefore the more tactics it can see.

Weak engines tend to use only alpha-beta. It's insufficient because the search space is too large. One would need to consider null-move, late move reductions and other advanced algorithms.

Now, to your second point. The common mistake made by chess engines at ELO range 1500 - 1800 is that their programmer doesn't understand chess programming. MicroMax, a super light chess engine (Google it if you don't believe) can play Elo 2000. Anything weaker than it is an indication that the engine has bugs and not performing as expected, as it should.

In general, an engine with a correct material evaluation function can perform Elo 2000.


Is there a good book on the 1927 Capablanca-Alekhine world championship match?

I am aware of ISBN 5278004010

Cons:

the book is in Russian, I don't know if there's an English translation

Pros:

contains all match games, most of them annotated (some games aren't annotated, contain just some short comments about particular moves at the end)
annotations by Alekhine himself
contains other games played by Alekhine in tournaments before the match

Also, Alexander Kotov wrote "Alekhine's Chess Legacy" (2 volumes), you may try looking for games from that match in those books. Kotov was a fan of Alekhine, a strong tactical style player and he was good at explaining chess to players below grandmaster level, so I think annotations authored by him would suit you.


Is this Rook versus Bishop endgame winning for white (white to move)?

This ending is drawn, and the main thing that Black needs to avoid, and which White should aim for, is having her king driven toward the a1 or h8 corner (the problem being that those squares are the color that the remaining bishop travels on). White cannot force Black into either of those corners from this position, and so it is drawn. To see that the others are "good" corners, note that in the following position Black need only keep shuffling the bishop along the b8-h2 diagonal, and White has no way to progress toward mate, as a rook check on the eighth rank can always be blocked safely (which isn't true in the "bad" corners).

[fen "k7/4R3/K7/8/5b2/8/8/8 w - - 0 1"]


10+ moves later is enough! Note that material-wise, Black is already winning. The sacrifice Nc3 is far too speculative. What is the worst thing that could happen to Black? Nd6+, walling him in, or even followed by some Re1+ after exchange on d6. Thus, rather sacrifice a pawn while White hasn't even castled, than allow any swindles.


Worst tournament performances of reigning World Champions

Looking through this list of strong tournaments, among those that stand out are:

AVRO 1938, where Alekhine finished 6/8.
Tillburg, 1996, where Karpov finished 6/12.
1st Grand Slam Masters Final (2008), where Anand finished in last (6th) place.


Why can I only move my Queen vertically?

The Rook on e8 is pinning your Queen against the King. You cannot expose your King to check.


Just where is the list of FIDE approved clocks?

Here is the document that includes that. See section 5.5.

https://www.fide.com/FIDE/handbook/Standards_of_Chess_Equipment_and_tournament_venue.pdf


How to use the Ponder option in stockfish / UCI

The only purpose of the "Ponder" UCI option in Stockfish is to inform the engine about that you will use pondering so that it can consider this fact in its time management, as can be seen in https://github.com/official-stockfish/Stockfish/blob/46ce245763705c89dba60dcfda549dc1f64eb48b/src/timeman.cpp#L131-L132:

  if (Options["Ponder"])
      optimumTime += optimumTime / 4;

Since the option is boolean, you should enable it by setting it to "true", i.e.:

setoption name Ponder value true

Stockfish will then use a more aggressive time management, since it knows that it will also be able to use the opponent's thinking time.

This is consistent with how the UCI protocol defines the ponder option:

        *  = Ponder, type check
            this means that the engine is able to ponder.
            The GUI will send this whenever pondering is possible or not.
            Note: The engine should not start pondering on its own if this is enabled, this option is only
            needed because the engine might change its time management algorithm when pondering is allowed.


How did chess change over the 2010s and should I keep anything in mind for buying books from before 2010?

Given that you are even asking this question, I am going to be a bit presumptuous and guess you are, like me, not a highly rated (elo > 2000) player.
For chess books that are not about opening theory, I would not worry too much about the age of the book. Sure, the occasional study or evaluation has been adjusted based on computer engines, but these are surprisingly rare and inconsequential for most of us. Endgame theory has changed little in the last 50 years and that which has is mostly relevant only to very highly rated players. If Bobby Fischer were to teleport from 1972 to today, he would still be a very good chess player and he learned from books which are considered ancient today.
Opening theory does change more frequently but even then, this is mostly of concern to highly rated players looking to extract tiny advantages from deeply memorized computer lines. If your intention is to simply get a feel for a specific opening and its common variations, I think anything reputable from the last 20 years will be helpful, although you should probably complement this by looking at up to date chess databases to make sure popular variations are covered. Which you should do anyway even with a new book.


What was the first "Opening Repertoire" book?

1939: White to Play and Win by Weaver Adams. Adams believed that 1.P-K4 (1.e4) wins by force. In this book he presents his recommendations for White against the various Black defenses. For example, against 1...e5 he recommended the Bishop's Opening 2.Bc4. He continued to revise his system and write more books, e.g., he switched from 2.Bc4 to 2.Nc3 in his 1946 book Simple Chess.


After 1.Ra6, Black is in Zugzwang - the purpose of Ra6 is to prevent Black's a-pawn from moving. Now Black must move his rook.  If he moves it off the h file, then White plays Rh6#.  However, after 1... Rh8, White mates anyway with Ng7.

Black can hold (after a fashion) if his Rook can control g7 and h6.  After 1. Ra6, he will have to leave one of those squares undefended.

And to answer your question directly, Black has no good moves after Ra6. He's going to get mated on g7 or h6.  So Rh8 is as good as any.


Why does the black king evade to f8, and not to h7?

Kh7 would also result in mate due to Qh5. So both moves are equally "good" Kf8 Rg8 maybe was seen as less obvious than Qh5.


This is a famous task, originally tackled by Sam Loyd and only improved a century later.  See http://www.chessvariants.com/problems.dir/twokingstask.html, which gives the refinement by Ponzetto:

[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
1.e4 d5 2.exd5 Qxd5 3.Bd3 Qxa2 4.Bxh7 Qxb1 5.Bxg8 Qxc2 6.Bxf7+ Kxf7 7.Rxa7 Qxc1 8.Rxb7 Rxh2 9.Rxb8 Rxg2 10.Qxc1 Rxg1+ 11.Rxg1 Rxb8 12.Qxc7 Rxb2 13.Qxc8 Rxd2 14.Qxf8+ Kxf8 15.Rxg7 Rxf2 16.Rxe7 Kxe7 17.Kxf2

For reference, here's the original Loyd solution:

[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
1. c4 d5 2. cxd5 Qxd5 3. Qc2 Qxg2 4. Qxc7 Qxg1 5. Qxb7 Qxh2 6. Qxb8 Qe5 7. Qxc8+ Rxc8 8. Rxh7 Qxb2 9. Rxh8 Qxa2 10. Rxg8 Qxd2+ 11. Kxd2 Rxc1 12. Rxg7 Rxb1 13. Rxf7 Rxf1 14. Rxf8+ Kxf8 15. Rxa7 Rxf2 16. Rxe7 Rxe2+ 17. Kxe2 Kxe7

[ ETA: Incidentally, while the linked article leaves it as an open problem, it seems like it would be a very straightforward task to show that 16.5 is optimal; at least at first glance I don't see any lines that have captures by both sides on all four half-moves in moves 2 and 3, which would imply that some form of 'off move' along the lines of White's 3. Bd3 is a strict necessity within the first few moves. ]


Why is the 'classical' Nimzo-Indian called the Noa variation?

The Oxford Companion to Chess says that the Noa Variation of the Nimzo-Indian was played regularly by Josef Noa, but that he reached the position after 1.d4 d5 2.c4 e6 3.Nc3 Bb4 4.Qc2 Nf6.


Why doesn't the black bishop just capture the white knight?

Black could take the knight on e5, but then after d4 the bishop doesn't have any good squares. If he tries to retreat to d6, knight and bishop will be forked with e5. In the end white will have better development and better central control, it definitely looks like a ready-made attacking position for white.

rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Bxc6 bxc6 5.Nxe5 Nf6 6.Nc3 Bc5 7.a3 Bd4
8.O-O Bxe5 9.d4 Bd6 10.e5


Arena Question - How Do I Set it So Arena Has a Time Limit But I Don't?

Version 3.5: I simply use from the menu: Levels/Adjust and from the dialog box select "Time per move". Whatever time you put in limits the computer's analysis time but of course you take as much time as you need to respond. :)

Of course same goes for "Fixed search depth".


Why is Russia no longer dominating the world chess championships?

The Soviet Union used to dominate chess because it had state-sponsored schools that provided high-quality trainers. After the Soviet Union broke up, funding dried up, and many of these trainers emigrated. Naturally the competitors caught up.
Vladimir Kramnik discusses some of this in an interview he gave with chess.com.

Chess.com: Much has been written about the legendary Soviet chess schools. You attended the Botvinnik school in the 1980s. What was it like?
Vladimir Kramnik: People always have a bit of an exaggerated picture of the Soviet chess schools, this idea that there were these concentration camps for kids, working 25 hours a day on chess. No, it was just a two-week session, held twice a year, and even during these two weeks, it was not so terribly intense.
The main asset of the Soviet chess school was actually the high standard of trainers throughout the country. In a world without internet and little exchange of information, this knowledge was hidden away behind the iron curtain. The reason the balance of power started to change after the iron curtain came down was because many of these Russian trainers emigrated, allowing western players and Chinese players to learn from them and get closer to the Russians.
You were 14 when the cold war ended and the Soviet Union began to collapse. How did that affect you?
Of course there were some issues, but I was just a kid at the time, so it didn’t make that big an impact on me. I think it was a much more difficult time for the older generations. For me, there were plusses and minuses. The plusses were that I could finally start going abroad to play tournaments, of my own will. The minuses were that all the state support for chess started to disappear.
The years 1990-1992 were a very difficult time financially in Russia, and many talented players of my generation didn’t manage to improve quickly enough. They ran out of money for trainers, and they ended up stuck at the same level. I was quite lucky in that I benefited from the state support of young talents when I was small, and then I reached the top of the game very quickly. But initially, money was not always easy.


How to determine if a position is open or closed in a "rigorous" fashion?

As a chess player who currently studies computer science, I found this question very interesting so here's my thoughts on the topic. You already know how chess books categorize open and closed positions and you may also know that a semi-closed position is one with some of the characteristics of an open but not all. As you understand this makes the line between closed and semi closed positions not easy to be seen. So my recommendation is to use a number to describe the "openness" of a position(although 50% may be a problem). Now some things I thinks you might find useful for implementing you machine learning algorithm. Firstly, I will suggest you to take a look at this article https://chess24.com/en/read/news/how-do-chess-engines-think in the section about position evaluation. Now, some parameters you might use:

Number of pawns(a position with no pawns is apparently wide open).
Number of pawn moves(assuming a position with three pawns each,there's a big difference if they are on f2,g2,f7 and f7,g7,h7 respectively and if they are on c4,d5,e4 and c5,d6,e5.
As you see in 2 you may give an extra weight for pawn moves in the center. Generally it will be a good idea to give extra weight for anything open in the center. This will be more clear in 4.
Number of open and semi-open files. The ones in the center again should have an extra weight.
Open diagonals. Note that diagonals with one or more isolani should be counted almost as opens(As an example think about the Indian's bishop targeting d4 and b2 when the c pawn is not on c3). And you should of course take into consideration the length of the diagonal.

Note that essentially you don't judge the whole position, just the pawn structure. That's why count the available moves of every piece is a mistake. This just measures the mobility of the given piece and doesn't necessarily has something to do with the pawn structure. For example, in a position with no pawns a Knight on a1 has only two moves while in a closed King's Indian the f3 Knight has seven( only one is occupied by the King). Some of them drop the piece but they are legal moves nonetheless.

Hope that helps a bit!


Doubt about best move in lichess.org training puzzle

No. After ...Bc8??, Ra8+ checks win for white.


How should Black defend against the Steinitz attack? This line of attack seems to break so many opening theory principles (don't move same piece twice, don't overextend, develop minor pieces ASAP) that I am surprised it's not immediately punishable.

Why should you defend, at the first place?? All of your observations are correct, so we can conclude that e5 is a bad move. Black is better here, but the only reason you do not see a question mark behind this move are following facts:

Pawn at e5 is White's only weakness;
Black has no open lines or diagonals that can be used to attack the e5 pawn;
White can defend e5 pawn with d4 which means that black will have to attack it with d6/f6 at some point-this will give White the chance to get himself rid of his ONLY weakness by exchanging it.
No matter how Black reacts, White will still have small spatial edge-e5+d4 pawn chain vs e6+d5 pawn chain, or d4 pawn vs e6+c6 pawns. For better understanding of these middle-games consult book Andrew Soltis-Pawn Structure Chess;

Still, Black can gain his fair amount of space in the center and equalize gradually like in any other viable semi-open game.

Since White played twice with a pawn and has overextended himself, the best would be for us to continue developing using initiative against e5 pawn to get tempo.

Below are the variations that demonstrate what I have stated so far:

[fen ""]

1.e4 e6 2.e5 Nc6!? ( 2...d6!? ) 3.d4 d6 4.exd6 ( 4.Nf3 dxe5! 5.dxe5 ( 5.Nxe5? Qxd4 6.Nxc6 Qxd1+ ) Qxd1+=) ( 4.f4? dxe5! 5.dxe5 Qxd1+ ) ( 4.Bb5?! Bd7 5.exd6 ( 5.Nf3 dxe5 6.Nxe5? Nxe5! 7.Bxd7+ Nxd7-+ ) Bxd6= ) Bxd6 5.Nf3 ( 5.Qg4?! Nf6! 6.Qxg7 Rg8 7.Qh6 Nxd4 8.Bd3 e5 9.Bg5!? ( 9.Bxh7? Rh8!-+ 10.Bg5 Rxh7 11.Qxh7 Nxh7 12.Bxd8 Nxc2+ 13.Kd1 Nxa1! 14.Bh4 Bf5-+ ) 9...Ng4! 10.Bxd8 ( 10.Qxh7?? Qxg5-+ ) Nxh6 11.Bh4 ( 11.Bxh7?? Rh8-+ ) Bf5-+ ) Nge7 6.Bd3 e5 7.dxe5 Nxe5=

I was trying to find this line and the only thing I found was a main line from above, given by Lev Psakhis. His line starts with 2...d6 and transposes to the main line given above. The move 5.Qg4 shows my own analysis, since it was not mentioned anywhere but I believe it can be tricky. Notice the traps that I have shown in the above sidelines-they can be very useful to you during play. Also, notice how in time Black frees himself from Whites small spatial advantage and equalizes.

If you do not like these you can always transpose into normal French defense with 2...d5 and 2...c5 is also viable here.

If you have further questions leave a comment and I will reply as soon as I can. Hopefully this answer helped you.

Best regards.


Sicilian Defense: Smith-Morra Accepted, Scheveningen Formation, 7.O-O

I wouldn't go for 8...e5 in this position. When black plays e5 in Scheveningen/Najdorf and even in Smith-Morra gambit, it is usually connected with a win of tempo (attacking the knight on d4) or black is forced to do so because white is threatening e5. This simply isn't the case in the position above, as 9. e5 won't do much harm.

Finally, the 8...e5 move can cause you a lot of trouble because of the weak d5 square and the a2-g8 diagonal. Therefore, I would suggest you leaving e5 for future.

8...Nf6 is a much more logical developing move and I would play it. Not surprisingly, it stands as the move #1 in my database with a great statistic (72.1% for black). For example:

[fen "r1bqk1nr/pp2bppp/2npp3/8/2B1P3/2N1BN2/PP3PPP/R2Q1RK1 b kq - 3 8"]

8...Nf6 9.Qe2 O-O 10.Rfd1 {and only then (when white threatens e5) play 10...e5 yourself} 10...e5

Another try for black is 8...a6 (covering the b5 square), but I think there will be enough time for that after finishing the development (if needed at all).

EDIT: As @Evargalo noted in the comments, in the 8...Nf6 line I gave above, you can also try 9...Ng4 with the idea of blocking the e5 break by putting a knight on e5:

[fen "r1bqk2r/pp2bppp/2nppn2/8/2B1P3/2N1BN2/PP2QPPP/R4RK1 b kq - 4 9"]

9...Ng4 10.Bf4 Nge5

The key idea of the manoeuvre is that black doesn't mind doubled pawns on the e-file, because he is pawn up and thanks to those pawns he can control the central squares d4 and d5.

Other possibilities shown by @Evargalo are to deviate from standard set-ups in Smith-Morra gambit by playing 10...Qa5 or 10...Bd7, I guess they are at least as good as 10...e5 so thanks to Evargalo for pointing them out.


Can one win with two dark square bishops and two light square bishops and his opponent has only one queen?

What you're referring to is a so-called "7-man" ending (2 kings, 1 queen and 4 bishops). Luckily for you, we have 7-man tablebases which are even available online and which allow us to analyze every possible legal 7-man chess ending.

[FEN "1q1k4/8/8/8/B7/1B6/1B6/2B1K3 w - - 0 1"]

Randomly setting up the above position shows that white is indeed winning, and generally most positions seem to show white winning. However, this isn't always the case, for example the following is a draw (white to move) because of the fact that black can either fork the king and one of the bishops, or can fork two bishops:

[FEN "3k3K/B3q3/8/8/8/8/B7/2B4B w - - 0 1"]

The tablebase also shows how the win often doesn't require that many ply, depending on the starting position of course.


Is it true that Chess is generally more played by men?

Among active players in the United States, about 15% seem to be women.

If you look at the rankings on this page, there are currently 9513 women active out of 64634 total players. That's 14.7%.

My guess is that the composition of female players skews more heavily towards juniors than the composition of male players, but I didn't find any numbers on that. I say this because I saw more female players at scholastic tournaments as a child than I do now at open tournaments as an adult.