How can one determine the opening or transposed opening from the existing pawn formation/structure?

In one sense, I would simply say, "Yes, the pawn structure would be the first indicator that one has entered/transposed into a given opening." But since there's no other answer here as of yet, I'm going to take the liberty to say a bit more, pushing a little further than the question as you asked it.

Not to put too fine a point on it, but here's one way to look at this matter: it is not so much that the pawn structure allows you to recognize what opening you're in (or have transposed to), but rather that the pawn structure nearly defines a given opening. In fact, while at certain playing levels very precise knowledge of opening lines is definitely crucial, one can get quite far without focusing too much on particular openings, but instead just on particular structures, and understanding the sorts of plans and piece developments that are appropriate for given structures.

This kind of approach is very much in the proverbial spirit of being taught to fish, instead of being given a fish (read: an opening line). One can't be ignorant of particular lines entirely, as one could get "move-ordered" into positions/structures one does not want to play; my main point, though, is that I think many beginning and intermediate players overemphasize knowledge of particular opening lines, and can sometimes get too caught up on labels/names that, ultimately, don't really matter, and distract from more useful considerations.

Here's an example of what I mean. Consider a game that starts with a Trompowsky Attack move order, 1. d4 Nf6 2. Bg5, which then proceeds with 2. ... e6 3. e4 Be7 4. Nc3 d5 5. e5 Nfd7 6. Bxe7 Qxe7 7. f4, reaching the following position:

rnb1k2r/pppnqppp/4p3/3pP3/3P1P2/2N5/PPP3PP/R2QKBNR w KQkq - 0 1

This same position is reached much more often via a French Defense move order: 1. e4 e6 2. d4 d5 3. Nc3 Nf6 4. Bg5 Be7 5. e5 Nfd7 6. Bxe7 Qxe7 7. f4 (in my database, there are only 23 games which include the previous move order, but 4050 which include this one). So, though we started off with a Trompowsky, we've ended up in a position that would now be termed the Steinitz variation of the French Defense. But what's in a name, really? If the Trompowsky was as old as the French, maybe it would be the other way around and we would say that in the latter case what started as a French transposed to a Trompowsky.

Here's my point: how we got here doesn't matter once we're here, and what we call it doesn't matter either for our chess playing. I have actually heard players say, in analogous situations, something along the lines of, "Oh, so now I need to learn the French Defense too." But this doesn't really make sense, any more than it would for a French Defense player who goes for this position to think that she suddenly needs to start picking up books on the Trompowsky. What each player really needs is to understand the structure that arises, regardless of what move order is used to get there, and regardless of what name for an opening the position receives.

Having said all that, I should probably say something about "learning to fish." One good resource is Andrew Soltis' classic Pawn Structure Chess, which examines appropriate plans in given structures via many illustrative games, in chapters that are broken down by opening families, with titles like: The Caro-Slav Family, The Open Sicilian-English, The King's Indian Complex, The Panov Formation, etc. You'll find that the reader reviews in the link generally solidly endorse Soltis' book; so do folks like Jeremy Silman.

Another book which uses illustrative games to explain certain kinds of pawn structures is Dražen Marović's Understanding Pawn Play in Chess. One difference from Soltis' book is that the chapters are broken down by the concrete aspects of various pawn structures, with titles such as Isolated Pawns, Doubled Pawns, Pawn-Chains, Pawn-Islands, etc. John Donaldson gave a very positive review of Marović's book.

I'll also mention Hans Kmoch's older work Pawn Power in Chess from 1959, because I bought that book early on when I got into chess, and though I wasn't really prepared for it at the time, I think it has a lot going for it. You can get a good sense of the book and its worth from the preview and the reviews in the link. But as everyone who ever mentions this book will say in one way or another, Kmoch tries to be overly "scientific" in his approach and introduces a lot of unfortunate terminology that does more to obscure than enlighten. (For instance, leucopenia and melanpenia are coined for light-square and dark-square weaknesses, respectively.) But if you get past that kind of jargon, by just ignoring it best you can, there is truly useful information in the book, and it comes in the form of a typically inexpensive Dover edition.


Chess Clock App that does not pause when put in the background?

I use pomello.

This isn't a timetracker really. It's more for those who practice the pomodoro technique. It tracks the number of pomodoros you can achieve while allowing you to also tag disruptions and keep you focused until your break. I picked this particular one because it's integrated with trello. The integration allows it to tag your work items with the number of pomodoros you've done on that work item.


Is it the right choice to lose the queen for two rooks?

If it is white to move, he should probably play c3, Qb2 and only then Rxb7, not even allowing black the choice to trade the queen for two rooks. I don't see how black can defend against this and the resulting position should be winning for white. Maybe a computer will tell you that immediately taking on b7 is even stronger, but for a human this entails a certain amount of risk, whereas c3,Qb2,Rxb7 keeps complete control.

If it is black to move, he should probably play Kb8 with idea of playing Ka7 and Rb8, defending against c3, Qb2, Rxb7. In that case Rxb7 might be whites best choice and it looks indeed like a strong continuation. Something like 2.Rxb7 Qxb7 3.Rxb7 Kxb7 4.Qb4 Ka7 5.c6 Rb8 6.Qc5+ Ka8 7.Qxc4 Ka7 8.Qc5+ Ka8 9.Qe7 Rc8 would also result in a position where white is in complete control and can push his extra pawns with c4, d5 and maybe intrude with the king h4, Kh2,Kg3,Kf4,Kg5,Kf6.

Not taking the rook after Rxb7 is not really a choice for black. In that case he would just be lost without any counterchances.


We found out that we made an illegal move later on in the game

FIDE Laws of Chess 7.4a

  If during a game it is found that an illegal move, ..., has
  been completed, the position immediately before the irregularity shall be
  reinstated. If the position immediately before the irregularity cannot be determined
  the game shall continue from the last identifiable position prior to the irregularity.
  The clocks shall be adjusted according to Article 6.13. The Articles 4.3 and 4.6 [touch move] apply
  to the move replacing the illegal move. The game shall then continue from this reinstated position.

Of course, if you are playing with your friend, you can choose to do whatever you feel would be best. The above is simply what would happen in a FIDE tournament.


Do chess engines really prune more than 90% of branches?

Yes. Chess engines prune moves quite extensively. Chess programming is all about pruning.

When an engine says "search up to depth 15", it really mean depth as in iterative deepening depth-first search. It doesn't mean that the engine attempts to search everything up to depth 15. No good chess engine would search everything to depth 15.

It's complicated, but most of the bad moves should be reduced by depth (or even eliminated), and some critical lines variations extended beyond depth 15.

90% pruning is not uncommon, in fact it'd be more like 99.999999999999999999% according to your definition.


Can one side force a loss in regular chess?

There is likely not a way to force a loss. Selfmates are relatively rare, and one can probably not be forced from the opening position.

The best plan, paradoxically, is likely to try to capture as many of the opponent's pieces (but not pawns) as possible, while keeping your own pieces to be better able to force your opponent. The opponent's pawns are kept because they have very little choice as to where they can move, and can also be easily blocked to avoid the opponent moving them before you want them to. For example, in the following position, the f-pawn is blocked and the king cannot move, so Black has no choice but to advance the g-pawn and will have to checkmate White in two moves:

[FEN "3Q4/8/8/4N3/6p1/7k/5p2/5N1K b - - 0 1"]

  If not, can one side force a draw

Well, if checkmate indeed cannot be forced, then almost by definition a draw could be forced. The game can't go on forever, after all. If nothing else, the players will eventually run out of pawns to move or pieces to capture, and the 50 move rule will come into play.


Can a rook win against a knight in the endgame?

In the specific position that you mention, the answer is a resounding no.  The king and the knight will defend each other, and white will not be able to force mate.

However, the knight is a clumsy piece.  If the knight is not positioned perfectly, then the rook will frequently be able to drive the knight to a bad square and deprive it of moves.  Eventually, the knight may be captured, or the king might be checkmated.

As an example of a position where the rook can win, take the following:

[FEN "8/1n6/8/8/2R2K2/8/5k2/8 w - - 0 1"]
[SetUp "1"]
[PlyCount "17"]

1. Rc2+ Ke1 2. Ke3 Kd1 (2... Kf1 3. Rf2+ Kg1 4. Rd2 Nc5 5. Kf3 Ne6 6. Kg3 Kf1
7. Rd5 Nc7 8. Re5 Na6 9. Kf3 Kg1 10. Rg5+ Kf1 11. Ra5) 3. Rb2 Nc5 4. Rb6 $22
Na4 5. Rb4 Nc3 (5... Nc5 6. Rd4+ Kc2 7. Rc4+) 6. Kd3 Na2 7. Rb1+ Nc1+ 8. Kc3
Ke2 9. Rxc1 *

Here, white can win starting with 1.Rc2+.  The plan is to drive the king to the first rank and then attack the knight while improving the position of the rook.

In your question, you mention specific cases where the king and the knight are close together.  In these cases, it is very important to know two key positions:

First, in this position, black can hold the draw:

No matter what white tries, the white king cannot approach the black king due to the knight.  Black will be able to squeeze out with ...Kb2.  Black's plan is to mark time by playing ...Na3 and ...Nb1.  White cannot make useful progress.

This position, almost the same, has one major difference - black can no longer mark time with the knight:

If white plays a waiting move, for example 1.Re2, then black must lose immediately.  Any move will lose the knight or allow mate in one.

If you're interested in a specific position, you can check out the Nalimov Tablebases online.  They have completely solved every position with 6 or fewer pieces on the board.


How can I make chess interesting and fun for beginners and doubters?

You need to show them how to win! Letting them win, or going easy on them, I don't think is the answer. Communicating a few simple chess concepts can go a long way.

Here's how I would approach it (once they understand the rules):

play a few games (noting the moves)
show them a few simple concepts such as the pin and the fork, the three opening principles, knights in pawn holes and good/bad bishops, the concept of the king net, and some simple patterns such as the back-rank mate, KRRvK mate and the rook-roll, or KRvK mate.
go over the previously played games and spot these concepts appearing.
go on and play some more games and note their improvement.

The problem is, most people have the mistaken impression that chess skill is directly related to intelligence. Because it's common for people to underestimate their intelligence, they don't believe they will be any good at the game and will most likely lose, while at the same time being perceived to be unintelligent because they failed at chess — no fun at all.

The key is to show them how to win via the communication of a few simple chess principles, which has the added benefits of improving their self-esteem, while at the same time giving them a glimpse into the underlying, invisible-to-the-non-chess-player beauty of chess.


What are "full piece" and "half piece" in chess?

blundering a full piece

or

being a full piece down

are typical expressions in English chess literature.
With the little word "full", the author wants to make clear that the player has not only lost the piece, but that they also received no consolation material in return, i.e. one or two pawns. An alternative expression is "blundering a clean piece" / "being a clean piece down".
The typical scale is:

The opponent blundered/sacrificed a piece for two pawns.
The opponent blundered/sacrificed a piece for a pawn.
The opponent blundered/sacrificed a full/clean piece.

("Sacrifice" or "blunder" generally depend on the positional compensation for the loss of the piece.)
The "piece" in question may theoretically be a any of the "pieces" knight, bishop, rook or queen (pawns are not "pieces" and the king cannot be captured), but typically you would expect it to be either a knight or a bishop (in the other cases it would rather be e.g. "being a full rook down" or "being a full queen down").
The term "half piece" does not exist, at least to my knowledge.


Information on adding opening knowledge to an engine

there are plenty of free online files of chess openings, here are a few:
https://www.pgnmentor.com/files.html#openings
http://scid.sourceforge.net/
https://www.bookup.com/ECO/chess_openings_ECO_-.htm
i could only find these links as of now. I will give you more once i find more


I do not know for sure, but my guess is that those accusations largely came from Kamsky's father, who was quite belligerent at the time.  In later intereviews, Kamsky tended to avoid discussing his father and that period in his career, so I doubt it has been revisited.


Can black make any progress in this end game?

It does look like a fortress. After 1...Qe2+ 2.Bb2 Qd2 White can wait with Ka2-b1-a2 or Bb2-a1-b2 depending on where the queen sits.

Black cannot bring the king to d4 because of discovered checks, so the best try seems to be to travel to d5 and play a3 when the pieces are Qd2, Bb2, wKb1. Then Rxa3 Kc4 prevents the rook from coming back to c3 because of Qxc3 simplifying to a winning pawn ending.

Alas, White still can play Bc1 Qg2 Re3 Kb4 Ra3 and wait with Ra3-e3-a3.

I believe it is a draw.


Solution: Use 'expect' script as shown below. Tested with stockfish_8_x64_modern.

  BlindKungFuMaster: "I think the main problem is that the uci protocol is a dialog."
    I agree!

#!/usr/bin/expect

spawn ~/stockfish_8_x64_modern

expect -timeout 1000  Linscott

send "setoption name Ponder  value false \r isready \r"

expect -timeout 1000  readyok

send "setoption name Hash    value 2048 \r isready \r"

expect -timeout 1000  readyok

send "setoption name Threads value 8    \r isready \r"

expect -timeout 1000  readyok

send "setoption name MultiPV value 4    \r isready \r"

expect -timeout 1000  readyok

set row8 "rnbqkbnr"

set row7 "pppppppp"

set row6 "11111111"

set row5 "11111111"

set row4 "11111111"

set row3 "11111111"

set row2 "PPPPPPPP"

set row1 "RNBQKBNR"

send "position fen $row8/$row7/$row6/$row5/$row4/$row3/$row2/$row1 w KQkq - 0 1 moves e2e4 \r isready \r"

expect -timeout 1000  readyok

send "go infinite \r"

expect -timeout 999999  readyok


Analyzing using Chess Engines - Giuoco Piano/Steinitz Variation

1) Can I agree with the Recommended Line of Deep Fritz 12?

Re3 is a perfectly reasonable move, and Stockfish 9 also agree's with it. This isn't to say that there aren't other moves to consider such as Qe2 or even the more passive Re1. Also bare in mind that some engine recommendations don't really follow our human style and as such are sometimes hard to grasp and follow through.

  2) Since there are many Engines now like Deep Fritz 12, Fritz 8, Fritz 16, Online Fritz, Chess Master Grand Master Edition etc. and still higher versions coming to market, which engine I can believe?

In truth all of them are similar, and to a club level player it really doesn't matter which engine you chose among the ones you mentioned. If those engines are giving you different moves for the same position its because all the moves are equally strong. Note that engines have versions because they are always being updated and as such it's import to have them updated as much as possible.

Personally i feel Stockfish is one of the best options out there because not only is it one of the highest rated engines, but it is also open source.

Now you shouldn't follow a move recommendation if you don't understand the logic behind a move, otherwise you just memorizing moves and not really improving. This is also why it is important to know the core chess concepts, such as piece development, center control, pawn structure, etc...

  3) By the way, what may be the logic behind 14. Qa4?

There are many ideias behind Qa4:

Avoid trading - It is the exact opposite of what you did with Ne5 allowing Nxe5 and the consecutive simplification to rook and bishop endgame being a pawn down. Its important to say that if the rooks are traded off then it will mostly result in a draw despite being a pawn down because its a opposite colored bishop endgame.
Connecting/Doubling rooks - Moving the queen off the first rank allows both rooks to connect later on with Ree1 or even doubling on the E file with Rae1
Queenside attack - By playing Qa4 you now pressure a7 tying down the knight to its defense. If unanswered then Ne5 will be a threat that removes the defender of a7 and allows you penetrate further with Qxa7. In this case even though you trade a knight down it gives you a lot of attacking options and more importantly the queens aren't traded. Also the B file is now open to a possible Rb1 that pressures the enemy king.

All these points make Qa4 better than Ne5 because they give you a lot more counter-play and fighting chances.


In the Caro-Kann, white dictates the speed and sharpness of play.  The exchange Caro-Kann typically shies away from tactical/aggressive positions.  In the advance bf5, white can play h4 which leads to very aggressive, open, and tactical games for both white and black.  You're likely looking for the Advance c5 which is a little more forcing for black that you're likely to get a tactical game.
Honestly, you're probably looking for a different answer to e4 if you want to play an aggressive game against white every time.  The Latvian Gambit is losing for black with correct play but if you know the lines, it's easy for white to go wrong quickly.


How to automatically evaluate a player's performance in a game?

The Site ratings at slow time controls can be quite reliable for servers where strong players congregate (ICC, FICS to name a few) as the ratings VERY closely reflect your true playing strength if you've played enough games. For very standardized rating systems such as USCF and FIDE/ELO, you will notice that the different rating classes tend to point to the types of mistakes those players are still making. NM Dan Heisman's Improving Chess Thinker does an excellent job discussing the types of errors players make across the rating classes.

Have you tried the many self-test books out there?  Igor Khmelnitsky's Chess Rating Exam and  Danny Kopec's Test, Evaluate and Improve your chess are excellent books that allow you to track your progress by seeing how you perform against graded test positions.

Your compare-my-moves-with-an-engine approach is another way to do this but once again, the ??/? moves are really only indicating tactical errors, not strategic or positional or even behavioral or time-management mistakes you might be making.

That's why playing slow time-control OTB/online games against equal-to-stronger opposition and getting them reviewed + critiqued by stronger players is an efficient way to improve. Your mistakes in every category (tactics, knowledge, thought process, time management etc.) get highlighted and you can simply measure progress in terms of the mistakes you've stopped making.

Though one fun variant you can try with an engine at home: Why not extend your engine-evaluation method to visually observe a player's quality/performance via evaluation graphs?  In other words, take engine evaluation scores per move and plot them (some free software like SCID does this for you) over the moves.

For example: Two rank beginners would have a game that looks like:

Notice how jagged these are. Both sides make many terrible mistakes (slopes of the spikes!) and also how often they fail to exploit the other person's terrible mistakes.

The spikes are always fun to look at :

Two intermediate (USCF 1400-1600) players might have games that look like:

It does look jagged, but notice how the y-axis (engine evaluation) is way smaller ... indicating that these players are more seasoned and play higher quality chess than the novices.

For a final comparison, a 1911 Grandmaster game would look like this:

No comments necessary here :)  These guys really don't make many mistakes, do they?

If you could devise your own heuristic for mapping the slopes + scale of an evaluation graph to  player skill/performance, perhaps this is one way to go? :)


Is there a freely available online 7 piece Endgame tablebase?

Original Answer:

7-men Lomonosov is free as an Android application.

Update - September 2018:

7-men Syzygy is available for free. Also available from Lichess.


Compiling Stockfish to disable own castling while allowing opponent castling

There is no need to compile your own version of Stockfish for this.  Instead you can just start from a position that omits castling rights for one side or the other. The FEN for the initial position without castling rights for White is
rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w kq - 0 1
and the FEN for the initial position without castling rights for Black is
rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQ - 0 1
The FEN can be entered into Stockfish using the UCI command
position fen FEN
where FEN should be replaced by the FEN in question.


Spielmann Gambit

[Event "?"]
[ECO "B02"]
[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/ b - - 0 1"]

[Setup "1"]

1. e4 d5 2. Nc3 (2...d4 {Probably the best move} 3. Nce2 {And probably the only reasonable retreat. White is losing the advantage of playing as White side here, that's true. That's why this is an 'unusual' reply. Both sides gonna fight for e5 square in this position. White can go for f2f4 and Ng1-f3.}) Nf6 3. e5 Nfd7 ( 3... d4 {Black dodges the gambit, resulting and open, even game with even material} 4. exf6 dxc3 5. fxg7 cxd2+ ) 4. e6 {Spielmann Gambit! White gives up a pawn to disorganize Blacks pieces, and will try to keep Black disorganized as long as possible. White has also good attacking possibilities on king side.} fxe6
5. d4 g6 (5... e5? { Trying to free up immediately, but... } 6.dxe5 e6 (6... Nxe5? 7. Qxd5 {Black has no material advantage and white has better position}) { Black gave up his extra pawn for reaching this defensive position. Worthy? I don't think so. White has a good play without giving up material.} ) {I think this is the best move for Black here. Fianchettoing bishop would give black a nice control over black squares in the center. Also ...g6 move closes e8-h5 diagonal, which will be used by white queen in some variations}

This is my favorite and totally awesome for a white player who wants to get initiative and attack.

After 5.d4, white plays to maintain control of central black squares, avoiding blacks freeing move ...e5, not letting black to develop, and attack from king-side using f7.


How to write a chess evaluation function?

EDIT for comment

The most important by far is the material count and PST already discussed in your link. You won't go anywhere unless your engine can count materials properly. Other than that, the common knowledge such as rook behind a passed pawn, castled king, pawn majority and mobility are important. Your human knowledge to chess should be sufficient.

ORIGINAL

The best way to improve it is to study the Stockfish source code. Read the comments, and study the implementation.

Code your engine, make it work with a simple evaluation function. Gradually and slowly apply Stockfish's ideas to your own engine.

There's many possible improvements. I can only list some of those. I will give you a link to the Stockfish source code below.

Two bishops advantage
Interpolate between middle game and endgame scoring
Bonus to pawn structures (the page only gives very simple PST values)
Calibrate the values better with a statistical model
Castled king
Number of squares controlled
Number of attacking squares near the enemy's king
Asymmetric evaluation (Stockfish doesn't do that but some engines like Chess Genius does that)
Pieces attacked by the king
Rook behind a pawn
Pawn on the check colour as bishop
Mobility bonus
Enemy checks
Rook on semi- or open file
Insufficient defended squares
Passed pawn that is not blocked
Candidate passed pawn (pawn majority)
......

Let's take some random examples from Stockfish. Please examine the source code yourself for details.

  https://github.com/official-stockfish/Stockfish/blob/69eb391cd779223c331fb0de80392cbd323055a9/src/evaluate.cpp

// RookOnFile[semiopen/open] contains bonuses for each rook when there is no
// friendly pawn on the rook file.
const Score RookOnFile[] = { S(20, 7), S(45, 20) };

and

// ThreatByMinor/ByRook[attacked PieceType] contains bonuses according to
// which piece type attacks which one. Attacks on lesser pieces which are
// pawn-defended are not considered.
const Score ThreatByMinor[PIECE_TYPE_NB] = {
  S(0, 0), S(0, 33), S(45, 43), S(46, 47), S(72, 107), S(48, 118)
};

and

// Scale down bonus for candidate passers which need more than one
// pawn push to become passed or have a pawn in front of them.
if (!pos.pawn_passed(Us, s + pawn_push(Us)) || (pos.pieces(PAWN) & forward_bb(Us, s)))
        mbonus /= 2, ebonus /= 2;


I have been doing this a lot recently. My iOS Syzygy 6-men apps require at least 2GB (possibly more) to run, which is not so easy for iPhones and iPads.

You gain the most benefit if you follow https://shop.chessbase.com/en/products/endspiel_turbo_4. This is also how I distribute.
Stockfish only memory map (mmap) your tablebase file when it is needed. So you might choose your files depend on what position you want.
I can't comment on iSCSI, NAS etc.


What are some good tactical opening moves?

Your description is a bit general. It's true that White tends to have more active openings as he has the first move, but it's possible to employ counter-attacking openings. As you love playing tactical openings, I would suggest adopting the Sicilian Defense as black - it is known to have a very distinctive active and tactical style.

Avoiding clever opening traps by your opponent is a matter of experience. When you fall for one, make sure to never fall for it again! By expanding your opening knowledge, you can enter the first stage of the game comfortably and exit it with a comfortable position.


Have you tried lichess studies ?
They can be used exactly like that. Let me give you an overview of how it works.
First you need to create a study, which you can do by heading to  https://lichess.org/study/ and clicking in the green plus button.
Multiple Members
As the What are Studies page explains, you can invite people to your study:

Let me quote the page that explains what these studies are:

Invite friends to analyse that new trendy opening. Invite your coach to teach you something. Invite 20 students to your lesson. Why not?
If your study is public, anyone can review it; invited members can chat, and invited contributors can update the study.
If your study is private, only invited members can review it, and invited contributors can update the study

Moves, Symbols and Arrows
The study members can create moves, or delete them. Any move anyone does changes the board that all other members see. Any move can have arrows to point possible moves or threats as well as symbols which are the red circles that normally are used to point key squares:

Comments
Any move can have comments, and these will be identified by who made them:

Annotations
The moves can also have the common chess notation:

Chat
There is also a chat, in case anyone wants just to say anything that isn't a comment to a move:

Chapters
This feature is solely available in studies, and allows you to have multiple chapters over the same study. It is useful in many scenarios like when you want to try several different ideas with quite some depth and extended analysis while keeping the main line clean. You could have the analysis of all your games in a tournament within the same study, and turning each game into a chapter.

Engine
As you would also probably be expecting, there is a feature to use an engine evaluation any time you need it. At the time of this answer the default engine is Stockfish 9.


Does using a less common opening make you a stronger player?

In general, less common openings tend to give weaker opponents issues, since they have yet to properly grasp many fundamental ideas of opening play and middlegame strategy, and if they don't know the concrete lines they may very well end up completely lost from a nonstandard opening position.

But a nonstandard opening doesn't make you into a stronger player just because you have good results on lower levels. In the end, you will hit a plateau with the nonstandard opening as well, when your opponents get sufficiently strong. Don't forget that these nonstandard openings are nonstandard for a reason: with correct play from your opponent, you're very unlikely to get any advantage, and you may even be running a serious risk of getting in trouble out of the opening.

With that being said, nonstandard openings are not to be written off completely, and at the 1700-1800 lichess rating range they can be quite a potent weapon, catching many players completely off-guard.


Chess.com has a review of 700 Opening Traps by Bill Wall:

  Bill Wall is a well known chess writer and his book '700 opening traps' is available as a free download from the website mentioned above, as well as his many other books and articles.

The book is available for download at http://billwall.phpwebhosting.com/ (this opens the book as a PDF).


Adding time to game played with chess engine

I don't know for sure on this, but if you go on Lichess, there is an option to add 15 seconds to your opponent's clock in live chess, I do not know with computer chess. I usually use Chess.com's live chess VS a bot.


Beginners question: Controlling the center

Once you control the center attack the enemy king and give checkmate!

However it's much easier said than done.

Normally there are two ways you can win control of the center and how you go about trying to win in each case is different.

1) You both fought for the center by moving pawns there but you managed to swap off or divert his pawn or pawns and now you control the center. Classically this could be via a gambit like King's Gambit (you played f4 on your second move to divert his e5 pawn to f4), Scotch Gambit or Goring Gambit (d4 on the second move followed by c3) or Morra Gambit in the Sicilian.

Because the center is open for your pieces you can move your pieces quickly towards the enemy king and go for checkmate. A good place to start studying here would be the romantic players of the 19th century like Anderson and Morphy.

2) Your opponent didn't really try and fight for the center with pawns instead he only moved some pawns to the 3rd rank, developed his pieces behind this pawn shell and aimed one or two of his pieces at the center by, for instance, fianchettoing his bishops. These would be openings like the Reti for white and the Pirc, Hedgehog and Hippopotamus for black.

The problem here is that because your opponent didn't weaken his position by fighting for the center with pawns he probably has a very strong defensive position which you need to try and break down. You will need to build up slowly with your pieces before trying to open his position with pushing one or more pawns into his position to break it open. Your opponent is hoping that you will create weaknesses in your own position when you do this and he can launch a counterstrike against your over-extended position. He could be right!

A good place to start here would be the games of the hypermoderns from the early part of the 20th century, players like Reti and Tartakower.


I think the chess youtuber with the channel that goes by the name of Hanging Pawns has a lot of good explanations about structure/openings. I downloaded a very nice book about it, but I suspect that I'm not yet on the appropriate level to concentrate on it, the book is called: Chess Structures: A Grandmaster Guide - by Mauricio Flores Rios.


Can the total number of possible wins/draws/losses be calculated?

Theoretically, we don't know, because we can't calculate it yet. Chess is not solved as an universal and general problem and we don't know that if two gods play chess in an infinite manner, which color wins or maybe it's just a draw.

Statistically, you can gather data from chess databases in websites, tournaments and computer tools to have an estimation. For example see this online databases.


Dealing with Sénéchaud Countergambit in King’s Gambit

Full disclosure: I don't play the King's Gambit.  My first thought (and note that I am NOT a master-level player) was 4. Nxg5 exf4 5. Nf3 (which, in and of itself, isn't sufficient to be an answer).

I decided to just do some Googling to try to learn more about this, and stumbled across analysis.cpuchess.com, which allowed a position to be analysed by various chess engines.

Here's what they gave me:

Houdini

  Nxg5 h6 5. Qh5 Qf6 6. Nf3 Qxf4 7. Qxe5+ Qxe5 8. Nxe5 d6 9. Nf3 Nc6 10. b3 Nge7 11. Bb2 Rg8 12. d4 Bb4+ 13. c3 Ba5 14. Nbd2 b5 15. g4 Bxg4 16. Bxb5 O-O-O

GarboChess JS

  Nxg5 Qe7 5. Bc4 exf4 6. Qh5 Nf6 7. Qxf7+ Qxf7 8. Bxf7+ Ke7 9. e5 Ng4

Fruit

Seemed to be locking up mid-analysis.

Stockfish

  Nxg5 Nc6 5. Qh5 Qf6 6. Bc4 Nh6 7. Nc3 Qg6 8. Qxg6 hxg6 9. Nd5 Bb6 10. Bb3 d6 11. d3 f5 12. Rf1 Bd7 13. fxe5 dxe5 14. exf5 Nxf5

Toga2

  Nxg5 Qe7 5. Nc3 exf4 6. Nf3 Bb4 7. e5 Bxc3 8. dxc3 d6 9. Qd5 Nc6 10. Bxf4 Nf6

Critter

  Nxg5 exf4 5. Qh5 Qe7 6. Bc4 Nf6 7. Qxf7+ Qxf7 8. Bxf7+ Ke7 9. Bb3 h6 10. Nf3 Nxe4 11. d4 Bd6 12. O-O Re8 13. Ne5 Nc6 14. Rxf4 Ng5 15. h4 Nxe5 16. hxg5

Observation

What I found most amusing about this was that all of them (except Fruit, of course) suggested 4. Nxg5 as the best move... but that most went different directions afterwards; 4. ... Qe7 on GarboChess JS and Toga2 being the only commonality, and even they diverged almost immediately.

... which leads me to conclude that the answer to "how would you try to refute" is 4. Nxg5 followed by "tactics."


Way to make a standard tell at beginning of game in Babas Chess?

This "script" is a command universal to all chess clients that run FICS, because it is a FICS command.

alias

Usage: alias [word [string]]

The "alias" command sets up a command alias so that 'word' is equivalent to typing 'string'.

PARAMETERS ----------

alias: If no parameter is supplied all of your aliases are displayed. word: The word for the alias. If 'string' is not supplied it lists the command associated with 'word'. string: The command string to use for the alias.

EXTRA INFO ----------

In order for an alias to actually do something, the server has to process each command you type. This is what happens:

If your command begins with a $, no alias substitution is done.
The first word is compared against your "alias" list, looking for a match.
The first word is compared against the server aliases, looking for a match.
If no match is found, the word is compared against the server commands. This means you can overwrite server commands with an alias.

SUBSTITUTION ------------ If the first word of your command matches an alias, it is replaced with the alias 'string'. The rest of what you type is substituted into the alias as 'parameters'.

You can access these parameters with special characters. They all start with an $.

$$ Replace with a $ (let's you use a '$' in the new command

$@ Replace with all parameters typed after 'word'

$n Replace with parameter number n

$-n Replace with all parameters 1 through n

$n Replace with all parameters from n onward

$m Replace with my name

$o Replace with my (last) opponent's name

$p Replace with my partner's name

$. Replace with the last person I told to

$, Replace with the last channel I told to

SPECIAL NOTES -------------

Use the "unalias" command to remove an alias.
You may not create an alias for the quit command, or for the unalias command.
A list of system aliases is available from the help system_alias file.
You can not put multiple commands with one alias.
Aliases are not transitional. This sequence of commands alias foo bar alias bar baz Will NOT result in foo being equivalent to baz.

WARNING: Be careful to avoid using an alias that can also stand for another command on the server. For example, "fg" could be a chess move (for f-pawn X g-pawn), so don't have "fg" be an alias. For similar reasons, it would not be best to use "t" as an alias since it is already assigned as an alias for "tell". You could do so, of course; but then you would not be able to use the system alias for tell unless you unalias your alias.

EXAMPLES -------- Some examples for useful aliases.

alias gm say Good move! If you type 'gm' it will say 'Good move!' to your opponent.

alias gg say Good game, $o! If you type 'gg' it will say 'Good game, !'

alias greet it waves at $1. How are you? $2- You can type 'greet playername Enjoy dinner?' and it will shout '--> yourname waves at playername! How are you? Enjoy dinner?'.

alias afk set busy is away for a bit Sets your busy string to 'is away for a bit' if you type 'afk' alias s1 seek 5 0 blitz f m If you type 's1' it will "seek" a 5 0 blitz game to all those who match your formula and set it to manual verification.

alias sf seek $1 $2 f Typing 'sf 3 0' will seek a 3 0 game and your opponent must fit your formula. 'sf 2 12' will seek a 2 12 game restricted to your formula.

alias 50 xtell 50 $@ You can now chat in channel 50 by typing in '50 whatever you want to say'. By using xtell the ',' system alias will allow fast communications to another channel.

SEE ALSO -------- system_alias unalias

AUTHORS ------- Created: 22 February 2002 DAV Last Modified: 30 December 2007 mhill


Apparently Fritz 14 is capable of reading the newer Syzygy format tablebases.  Certainly the latest Fritz can.

These tend to take up less space than Nalimov format, which used a simpler compression scheme designed for the benefit of older computers.  For example, the 5-man tablebases take over 7GB in Nalimov format but under 1GB in Syzygy format.

So I suggest trying Syzygy before giving up.


What is meant by openings with lot of theory versus those with little or none?

In chess, "opening theory" or just "theory" means "established opening lines": usually lines that have been studied and judged to lead to more or less equal positions, and appear in books.
It's unfortunate terminology since it matches neither the day-to-day meaning of the word (something that's contrasted to practice) nor the meaning used in game theory. But we're stuck with it.
While "opening" sometimes refers to a specific line, it's better to think of it as a game tree, that is, a collection of lines with a common origin. Openings with "lots of theory" are those with large game trees. This is usually a combination of two factors: long lines (the tree is deep) and lots of variations (the tree is wide, with a lot of branches).
Openings that are popular among top players will be studied more so will tend to have longer book lines. Openings that lead to positions with a lot of good moves will have lots of variations, while openings with forced moves will naturally have fewer variations.
In short, openings with lots of theory are those with more pages in opening books.
For example, Mastering the Chess Openings devotes 75 pages to the Sicilian Opening, and only 10 to the Caro-Kann. So we could say that the Sicilian has more theory than the Caro-Kann. Of course, different books will give you different numbers, but you get the idea.


How do players "see" several moves ahead?

The answer is that you only consider the most sensible and most critical options. This prunes the tree down to manageable proportions.

One easy example would be the fact that retreats are usually not threatening and therefore less likely to be critical. (Of course the downside is that actually dangerous retreats are often overlooked.)

To learn how to recognise potentially critical moves you have to play through master games, solve puzzles and play games. Over time your brain will store typical moves and manoeuvres in certain position. This ability is called pattern recognition. The more patterns your brain stores the stronger its intuitive move suggestions will be, you will be able to prune the tree more.

Another aspect is called "forcing moves". A forcing move is a move that requires a certain response, i.e. severely restricts the opponent's choices. For example checks, threats of checkmate and other kinds of strong threats. If your moves are very forcing the tree will resemble a path, because every step from this path is either illegal or results quickly in very bad things. If GMs calculate very long variations, these usually contain very forcing moves. In positions without forcing moves even the best players don't look very far ahead.

There is also a non-intuitve conscious part to "seeing ahead". Even if your brain provides you with only the most likely good moves, you still have to visualise the outcome of every variation in your head. That requires training as well, for example solving studies or tactical puzzles with long variations.


Complete game Szabo-Groszpeter, Kecskemet 1984

It looks like the game ended after a5. In Van Perlo's Endgame Tactics (Page 397 - ISBN 978-90-5691-494-3) it is described as following:"Here, at move 61, the game was interrupted, according to the rules applied at the time in the Hungarian Team Championship. The adjourned position was sent in for adjudication and the allgrandmasters committee declared the game a win for White."
He then give two main lines (main line with Kb8).


Can you identify the design of these chess pieces?

It’s not exact match, but it’s possible that your set is what is called a St. George-style set.
Compare your set to this image from the Staunton chess set Wikipedia.

The way the kings, bishops, queens and pawns are built, in comparison with your set and the image above, are very similar. The rooks and knights are not exact nor are the dimensions the same. I would suspect that what you have is a variation and/or  modernized design of the St. George-style chess set, such as a mesh with the Staunton perhaps.
Here’s an article about the St. George-style that might be of help.


What is most important for improving chess skills?

Disclaimer: USCF B-player here.

My advice would be to play marginally higher-rated players and ask them for help in determining what one could do better.  Most people will fall over themselves to help someone who puts forth an honest effort (hence, web sites like this one.)  At tournaments, I've never had an opponent unwilling to go over a game.

I have had some surprises by entering my games into Crafty and letting it analyze every move.  You can see pretty quickly where things go sideways.  At my level the reason I lose is always tactical.  That is, after my move, Crafty shows how I'm losing a piece ;-)  It is encouraging that my opponents don't always make the best move, either, so I am not wholly doomed.

Back in the day I had an instructor (USCF Master) who advised A and B players: tactics, tactics, tactics.  That is, we could win all our games just by concentrating on the next 4 moves or so.  When that quit working, we'd be much better players.

I'd advise:

get an instructor who can beat you every time (+400 rating points, or so.)
learn a few openings pretty well.  It's hard to stay motivated when every game is a mess by move 7.
study problems
focus on having good games, not on winning per se.
don't be afraid to lose.
play a lot, record your moves, then run them through the computer.


Your post is perfectly fine here, my friend. Chess problems and puzzles are on-topic here, and we do need more. All kinds of all sorts are welcome. We just need to bring them here!
I think that out of the 14 open squares on the board, only:

 placing the Black king on both a6 works!

This is because placement on the squares:

 a1, a2, a8, a4, b1, c1, c4, d1, d2, e1, e2,  f1, f6, f8, g1, and h6 all result in an illegal position. This is due to the fact that Black either has no last legal move if it is White's turn, or it would've been impossible for the Black king to get around the current White pawn structure. Thus, they are not options at all. This explains the "retrograde-analysis" tag.

Therefore, remaining the square works:

 with the solution checkmate being 1. Rd6#.


Do chess clocks typically provide count up features?

It is not a typical use case, so you will definitely want to make sure that the clock you're purchasing does have a count-up mode (or is analog, in which case, you probably want to make sure it is quiet). The Chronos digital clock does have a couple of count-up modes (UP-1 and UP-2).


Adjusting parameters in the engine stockfish 6

I don't have Shredder so I can't tell you how to use it to adjust parameters for Stockfish. However, it should be similar to ScidvsPC which I have posted here.

What do you mean by depth seems rather low? What depth would you consider be normal? We need a position to continue the discussion.
I don't think Shredder uses syzygy tablebase at all, that is you aren't using any tablebase. You'll need to set it up yourself.
Which parameters you're unsure? There're not many in SF6. The most important is contempt factor, which means how likely the engine takes a draw. By default, a draw is zero. If you give the contempt factor like a negative value, the engine will prefer another line that is closer to zero. Thus, the engine will take extra risks than necessary.


Disclaimer: I wrote SmallFish.

I would recommend SmallFish on iOS. It's free, and it has the most powerful engine on iOS. It has very advanced analysis feature, look at the screenshot


Quintuple repetition and the FIDE's 2014 rulebook revision

First note that your link to Geurt Gijssen. Arbiter's Notebook. is broken. ChessCafe.com have put almost all their stuff behind a paywall.

The purpose of this rule and of the related 75-move rule (after 75 moves with no captures or pawn moves the arbiter can / must step in and declare a draw) are for the benefit of arbiters. In summary they are the "I've got a home to go to and a warm bed waiting for me" rules. The key point here being that these two rules do not require a player to make a claim but instead the arbiter can intervene to stop the game.

Your example is not a draw under the rule. Here is how it works:

White's alternate moves must be identical.
Black's alternate moves must be identical.
For 5 consecutive, alternate White's turns the position must be identical.
For 5 consecutive, alternate Black's turns the position must be identical.

If that gobbledygook sounds confusing here is an example of a drawn game under the new rule:

1) Nc3 Nc6
2) Nb1 Nb8
3) Nc3 Nc6
4) Nb1 Nb8
5) Nc3 Nc6
6) Nb1 Nb8
7) Nc3 Nc6
8) Nb1 Nb8
9) Nc3 Nc6
10) Nb1 Nb8
11) Nc3 Nc6

Note that after Black's 4th move White could have claimed a draw under the 3-fold repetition rule and after White's 5th move either player could claim a draw on their turn.

If either player deviates from the strict repetition then the conditions are not fulfilled. For instance if White's 3rd and 4th moves are Nf3 and Ng1 then the strict sequence required for the satisfaction of the rule is broken.

Note that the rule says "for at least five consecutive alternate moves by each player". If it said "either player" instead of "each player" then the position and sequence in question would be a draw. But the example fails because it is only identical before alternate White moves and not before alternate Black moves.

Since 3-fold repetition draws can only be claimed when the moves are recorded they cannot normally be claimed during rapid and blitz games. The new rules allow the arbiter to intervene and stop the game provided he has witnessed and noted the moves and continue with the next round or go home to bed.

30/12/2014: There were two International Arbiters at our club annual rapid championship last night. I asked one of them and he was very clear. The rule:

  the same position has appeared, as in 9.2b, for at least five
  consecutive alternate moves by each player.

according to him means that after 5 alternate white moves the position must be the same in the meaning of 9.2b and after 5 alternate black moves it must be the same in the meaning of 9.2b and that this sequence of moves must be consecutive i.e. the first repeating black position must come immediately before or immediately after the first repeating white position and not part way through the sequence.

PS It's probably worth noting the answer he gave to a supplementary question.

Question: What happens if after one player wins through resignation / checkmate / flag fall it is discovered that there was an earlier 5 fold repetition? Should the result be changed to a draw?

Answer: Emphatically no. Just as the 3 fold repetition rule is for the benefit of the players, they may choose to claim by it or not at the specific time the incident occurs, so is the 5 fold repetition rule for the benefit of the arbiter, he may choose to enforce it or not at the time the incident occurs. He may not enforce it retrospectively. The win stands.

Edit: Well, it seems that the IA I consulted was wrong. Hidden away in section 6.2a of the FIDE Handbook it says this

  A move is also completed if: 1.the move ends the game (see Articles
  5.1.a, 5.2.a, 5.2.b, 5.2.c, 9.6a, 9.6b and 9.7)

9.6a and 9.6b are the two new draw rules, 5-fold repetition and 75 moves with no captures or pawn moves. So, they are elevated by this throw-away clause to the same level as checkmate, stalemate, resigns and agreed drawn. The arbiter has no more choice than he does with checkmate, etc.


First of all, I think the question is largely opinion based. However, I'll try to answer from my own experience about the X-check variants, as some matters about the chess variants can be described and judged objectively. If you are asking whether the variants are suitable to be taught to beginners (in terms of rule simplicity), then sure, they are. If you are asking whether or not they would benefit the beginners by improving their normal chess play, then I'd say no - they would only give them wrong ideas and confuse them.

My reasoning for the statement above is, that the "first to X checks" variants employ opening theory and tactics completely different from normal chess; very few ideas from these variants can be taken over to normal chess. For instance, one of normal opening play ideas (dominate the center with pawns) seems to perform very poorly in the X-check games, as it puts the king in danger of checks. There are many situations where a single bad move very early on in the opening leads to a forced loss (see for example the wiki article you linked; this is also akin to losers chess). Thus, in order to survive, one must employ strange pawn structures, completely unsuitable for normal chess. Additionally, one often sacrifices piece(s) just to get that check in - again, not really applicable to normal chess. In normal chess, such sacrifices are useless, unless they lead to a forced win/advantage, whereas in X-check chess, you have to defend against them, as each one brings the rival closer to victory.

The third variant, as BlindKungFuMaster noted, is basically normal chess. I'd recommend to keep it simple in the beginning, just do normal chess. Try chess variants only after learning the basic concepts and good practices of normal chess - then it is interesting to compare how they do or do not work in the variants.


How to tweak a chess engine like SF to return a variation which is only slightly better than your moves?

Ok, so say the engine plays a move with white and values the position as +0.50 (slightly better for white). So now the human plays as black, and blunders a bishop. The engine now values the position as +3.50, but you want to play a move as close as possible to +0.50, v. g. +0.60. Is it what you're looking for?

In that case it seems the way to go is (from the POV of the engine); "the position after my last move was +0.50, so in the current position, if a move that improves that eval exists, I must play the one closest to +0.50. Otherwise (there isn't a move that improves my eval after my last move), play the best move available."
If this is your idea, I guess this is doable, and for someone who develops their own chess engine probably shouldn't be hard to code.

Maybe the idea can be improved. For example, if you blunder a bishop, probably it's a good idea the engine to grab the bishop than to play something really stupid.

In any case, I think it's definitely doable, probably with some refinement. (For example, it's not the same blundering a bishop in one than losing a bishop after a 10 moves combination; in the first case, IMO, the engine should take the bishop, but in the second one it should chose a sub-optimal move).


French Defense Exchange variation - Qh5?

6.Qh5 is not so great because Black has 6...Nbc6, both attacking d4 and threatening ...Nb4 trading off White's important light-squared bishop (it can't move to e2 or something because of ...Nxc2+). White seems to be better off preemptively defending the d-pawn with a move like 6.Nf3 or 6.Nge2.


Is the 50-move rule ever used in grandmaster games?

Yes, sometimes the 50-move rule comes up in grandmaster play. One recent example that comes to mind was the game Ushenina-Girya (Geneva 2013), in which the reigning women's world champion failed to convert a knight-and-bishop checkmate within the required 50 moves, and the game was drawn. So this is a case where it's a theoretical win, but the stronger side couldn't put it away quickly enough. I would imagine there are some similar examples in the rook-and-bishop vs. rook ending.

[fen ""]
[Event "Women Grand Prix Geneva"]
[Site "Geneva SUI"]
[Date "2013.05.06"]
[EventDate "2013.05.03"]
[Round "4"]
[Result "1/2-1/2"]
[White "Anna Ushenina"]
[Black "Olga Girya"]
[ECO "D11"]
[WhiteElo "2491"]
[BlackElo "2463"]
[PlyCount "251"]

1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Qb3 dxc4 5. Qxc4 Bf5 6. g3 e6
7. Bg2 Nbd7 8. O-O Be7 9. e3 O-O 10. Rd1 Qc7 11. Nc3 Bg6
12. h3 Rad8 13. Qe2 e5 14. e4 exd4 15. Nxd4 Rfe8 16. Bf4 Qc8
17. Be3 Bb4 18. f3 Qb8 19. Bf2 Bh5 20. Qc2 Bd6 21. Nce2 Bg6
22. a3 h5 23. b4 Ne5 24. Qb3 Nxf3+ 25. Nxf3 Nxe4 26. Nh4 Nxf2
27. Kxf2 Bh7 28. Nf3 Re7 29. Ra2 Rde8 30. Rad2 Bc7 31. Nfd4
Bb6 32. Qf3 Qe5 33. Kg1 a5 34. Kh1 axb4 35. axb4 Qg5 36. h4
Qh6 37. Nf4 Re3 38. Qxh5 Rxg3 39. Qxh6 gxh6 40. Nh5 Rg6
41. Re2 Rxe2 42. Nxe2 Kf8 43. Bh3 Bc7 44. Bf5 Rd6 45. Rxd6
Bxd6 46. Bxh7 Be7 47. Nhf4 Bxh4 48. Bf5 Ke7 49. Nd3 Kd6
50. Nc3 Kc7 51. Kg2 Kb6 52. Kf3 Bf6 53. Ne4 Be7 54. Bc8 Kc7
55. Bg4 Kb6 56. Nec5 Kb5 57. Nxb7 Bxb4 58. Nxb4 Kxb4 59. Nd8
c5 60. Nxf7 c4 61. Ke2 Kc3 62. Kd1 Kb2 63. Nxh6 c3 64. Bf5 Kb3
65. Bc2+ Kb2 66. Nf5 Ka1 67. Ne3 Kb2 68. Nd5 Ka1 69. Ke2 Kb2
70. Kd3 Kc1 71. Ba4 Kb2 72. Nxc3 Ka1 73. Nd1 Ka2 74. Bc2 Ka1
75. Kc3 Ka2 76. Bb3+ Ka1 77. Ne3 Kb1 78. Nc2 Kc1 79. Ba2 Kd1
80. Nd4 Ke1 81. Kd3 Kf2 82. Bd5 Kg3 83. Ke3 Kg4 84. Be4 Kg5
85. Kf3 Kf6 86. Kf4 Kg7 87. Kg5 Kf7 88. Kf5 Kg7 89. Bd5 Kh6
90. Ne6 Kh7 91. Kf6 Kg8 92. Nf4+ Kh8 93. Be4 Kg8 94. Nh3 Kh8
95. Ng5 Kg8 96. Nf7 Kf8 97. Bh7 Ke8 98. Bf5 Kf8 99. Nh6 Ke8
100. Nf7 Kf8 101. Ne5 Kg8 102. Ng6 Kh7 103. Be6 Kh6 104. Bg8
Kh5 105. Ne5 Kh4 106. Kf5 Kg3 107. Bc4 Kf2 108. Kf4 Ke1
109. Ke3 Kd1 110. Bd3 Kc1 111. Nc4 Kd1 112. Nb6 Kc1 113. Na4
Kd1 114. Be4 Kc1 115. Bd3 Kd1 116. Nb2+ Kc1 117. Nc4 Kd1
118. Bg6 Kc1 119. Bf5 Kd1 120. Nb6 Kc1 121. Na4 Kd1 122. Nb2+
Kc1 123. Nc4 Kd1 124. Kd3 Kc1 125. Kc3 Kd1 126. Bd3 1/2-1/2


Why does the Hyper Accelerated Dragon avoid the Rossolimo?

In the Rossolimo proper,

[FEN ""]
[Title "Rossolimo variation"]
[Startply "5"]

1. e4 c5 2. Nf3 Nc6 3. Bb5 g6

white usually holds back pawn to d4 and doubles black pawns with Bxc6, or later builds a center with an eventual c3 followed by d4.

In the Open Sicilian,

[FEN ""]
[Title "Open Sicilian"]
[Startply "9"]

1. e4 c5 2. Nf3 g6 3. d4 cxd4 4. Nxd4 Nc6 5. Bb5?!

none of these plans are available, and 5. Bb5 doesn't make much sense. Besides, the bishop on b5 is tactically vulnerable to a later black Qa5+ or Qb6.


What are the percentage rates for each promotion type?

Here are the percentages for each promotion type according to different sources:
|Promotion type  | ChessBase | TWIC | ICCF |
--------------------------------------------
| Queen          |      96.9 | 97.3 | 96.1 |
| Rook           |       1.1 |  1.1 |  1.7 |
| Knight         |       1.8 |  1.3 |  1.7 |
| Bishop         |       0.2 |  0.3 |  0.5 |

Details:

ChessBase: Percentages from 2006 ChessBase, with 3.2 million games, obtained from Wikipedia.
TWIC: Percentages calculated using my own script from 1.4 million games published in The Week In Chess, issues 920 (Jun. 25th, 2012) to 1358 (Nov. 16th, 2020).
ICCF: Percentages calculated using my own script from 0.8 million games made available by the International Correspondence Chess Federation, from the 1970s to 2018.


At what playing strength level should one be able to mate with King Bishop and Knight vs King?

A member of my club, rated about 1900 FIDE, had this in a championship blitz game about 2 years ago with 30 seconds left on the clock. He delivered mate with time to spare. IMs  have failed. Go figure. If you study and learn then you should be able to deliver mate. If you don't study then you won't. Playing strength doesn't have that much to do with it.


Magic Bitboards, Feeding in Randoms - Why have to find magic instead of just loading from disk?

Computing magics at statup is fine because it's done only once and not very slow.

  https://github.com/official-stockfish/Stockfish/blob/master/src/bitboard.cpp

// init_magics() computes all rook and bishop attacks at startup. Magic
// bitboards are used to look up attacks of sliding pieces. As a reference see
// www.chessprogramming.org/Magic_Bitboards. In particular, here we use the so
// called "fancy" approach.

Stockfish did it. Leaving the constants in the code is also fine. It's all about implementation.


I agree with you. Players of all level play the Italian, and especially the 4. d3 line because they have read 2750+ players do so to avoid "drawing" (which is true at this level) lines aka Berlin Defense, as stated by Dag Oskar.

I see a bunch of 1500 rated players playing these lines, shuffling around trying to get something out of it, with no understanding of what is going on. I don't really see the point to be honest. This is true that the Italian has some bite if you know what you do, but the Giuco Piano/Pianissimo tend to generalize way too much. Personally, I tend to avoid it from move one 1...c5 ;) because I want to play chess. I'll play 1...e5 again when the Italian will be out of fashion.


In general, the pawns should be on the opposite colour of the bishop, especially if this forces the opponent's pawns onto the same colour as the bishop.

This prevents the bishop from being bad (locked in by it's own pawns) and gives the bishop targets.

In my answer to When and why should I trade minor pieces?, I gave this sample position of a bishop dominating the knight:

[FEN "8/8/1k3b2/1p3p1p/pPp2P2/P1P3P1/8/1N2K3 w - - 0 1"]
[Site ""]
[White "Onoprienko"]
[Black "Khasangatin"]

  1. Kd2            Kc6
  2. Ke2            Kd5
  3. Ke3            Bg7
  4. Kf3            Bh8
  5. Ke3            Bg7
  6. Kf3            Bf6
  7. Ke3            h4
  8. gxh4           Bxh4
  9. Kf3            Bf6
 10. Ke3            Ke6
 11. Kf3            Kf7
 12. Kg3            Kg6
 13. Kh3            Kh5
 14. Kg3            Be7
 15. Kh3            Bh4
 16. Nd2            Be1
 17. Nb1            Bf2
 18. Kg2            Be3
 19. Kf3            Bc1
 20. Kg3            Kg6
 0-1

This position is cited from Understanding Chess Endgames by John Nunn


Why can't a dropped pawn deliver checkmate in Shogi?

I found this on the web:

The rule that a pawn can not give checkmate probably stems from the rule that a piece may not be placed in a position from where it is unable to promote or continue. A pawn may only give checkmate by being placed directly in front of the emperor; a position from where it is unable to move or promote. It can not take the emperor piece as it could with other pieces, and it can not be promoted until it moves again.
In Shogi, violating rules such as "Two pawns can not occupy the same column" or "a piece can not be placed in a position where it is unable to move or promote" results in an immediate loss for the one who violated the rule. Thus, by placing a pawn in this location, the player automatically loses the game by violation of a rule. The checkmate that the player gives doesn't matter because it was obtained through the rule's violation.
In certain Shogi variations, such as yari shogi, a pawn can be used to give checkmate.


Trompowsky: why does 1.d4 Nf6 2.Bg5 d5 3.e3 e6 score so highly for white in master games?

3..e6 closes the way for your light-squared bishop, but I don't think that's too good of a reason to reach such scores (I checked on ChessTempo and got similar numbers)

Please be careful about possible bias due to player strength differences. A move may score worse simply because it is often used as a "drawish weapon" against a stronger player. This is the case of the French exchange variation, where Black scores better in a symmetrical position! But there could be other reasons why an opening system is more common among weaker players

I would tend towards an explanation of this kind, since there does not seem to be a clear "refutation" in the position you show (4.c4, 4.Nd2, 4.c3 and 4.Nf3 all score similarly.

Please specify your own skill level for further advice on how to build a repertoire around these lines to be possible


Do the King's side and Queen's side pieces have different values because of which square color they start on?

There is no doubt that the value of a piece depends on where it is on the board, but the difference between b1 and g1 or between c1 and f1 is going to be very small and probably not worth worrying about for human players. (Position-dependent piece values are much more sensitive to the rank and centrality of the square, neither of which change in this case.)

One way to try to measure this would be to ask the all-wise Stockfish. :-) What does it say if you remove one of these pieces? Here's what I got using the Lichess analysis board to default depth (these are the evaluation scores after removing the white piece):

Queen's knight: -3.8
King's knight: -3.6
Queen's bishop: -4.7
King's bishop: -4.8

So if we are to believe Stockfish, the queen's knight is worth 0.2 more, and the King's bishop is worth 0.1 more than their counterparts. Seems like a relatively small difference to me, and it is probably dependent on depth. Still, for whatever it is worth, the small differences at least went in the same direction as your hypothesis!


Any chess database (chessbase online, for example) can give you general statistics on how often a move is played in a given position, which you can use to get a feel for how popular an opening is.  To see an opening's popularity over time, and other more sophisticated metrics, you could use a commercial product like ChessBase, which has options like 'Opening Report' which gives you graphs of frequency over time, top player games in the position, and the like.


The canonical site for publishing a new chess variant is https://www.chessvariants.com. Read some of the descriptions there to get a feeling of the format of presentation, register (it's free) and submit your chess variant. They have an intuitive form that helps you in the write-up.


An unsorted list of arguments for the vitality of chess problems (probably my answer is a little bit biased because I am an enthusiastic chess composer ...)

Computers: A lot of new ideas have been developed during the last decades. One reason for it is the rise of computer programs which help to check the correctness of a chess problem. This simplified the chess composition dramatically, especially selfmates and helpmates with very complex and long solutions are now possible...
Helpmates: by the way help mates. This is an area I know a little bit and during the last 20 years there was phantastic progress. Here some non representative samples
http://kobulchess.com/en/problems/originals2013/321-chess-problem-helpmate-viktoras-paliulionis.html
or http://www.yacpdb.org/#320933
or http://pdb.dieschwalbe.de/search.jsp. Study the solutions and look for other problems of these authors (and other like Caillaud, Mazlar ...) to find other good help mates ... also there are still  many open themes which are not realised. such as the '100$ theme' , the 'Oudot theme' or a helpmate with more than 27 moves...
Specialisation:  Chess compositions branch in many different ways. Some "theoretical" knowledge on certain themes is restricted only to a very small group of composers. So for example if you ask for the development of some themes for three movers (mate in three) the current state of the art is probably known only to a very small group of composers (probably less than 100 people world wide). I am definitely sure they know exactly how their field developed during the last years. And definitely they will argue for a good progress in their field of work. But from "outside" the progress seems very modest (of course I don't want to blame the three mover community but this is an area I know almost nothing  :-)... There is a similar situation in mathematics or other scientific areas where the current state of development is often only understood by a small group of experts...
Fairy chess: If you think of chess problems in the broader sense of generalized chess the we come to fairy chess. This is the genre where the chess rules and the stipulations are extended far beyond the orthodox setup. For example new varieties of chess (varieties of circe chess, ghost chess ,... et.al.) and many many different pieces have been developed during the last decades and all of them help to represent new ideas in chess problems (or can you think of triple check or ...). For much more on fairy chess look at juliasfairies.com
selfmate, retro problems ...: There are a lot of other areas where chess problems develop. For example look at  the (german) retro blog http://www.thbrand.de/retroblog/ where you can learn a lot about retro chess (if you are aware of german)...

I hope all this helps to believe in the vital functions. For much more infos check the websites I mentioned above


The queen has the most squares available to land on, I recommend you get well acquainted with the rules of the game in the official FIDE Handbook


Stuck around 2000 rating. Concrete advice for improving?

Without actually knowing your strengths and weaknesses, I'd suggest doing the following:

Studying endgames is a great idea - it will help you to convert equal positions into wins against players with worse endgame knowledge. However - an equal position has to be reached first.

Find out what style of play you excel in - and learn how to get into positions that fit that style. The most drastic example of this might be the Fried Liver Attack. An engine really doesn't mind playing black here (I mean - it's a free knight!), but human players, even Grandmasters, are just screwed; they are just not able to calculate a complicated position like that well enough.
Improving here starts with analyzing openings and getting a feeling for positions, the weaknesses and strengths they bare and what long-term consequences your moves make. Aim to always know why you make a move. To practice this, you take any position, make out weak and strong points and formulate a plan for both sides - then think about moves you want to play to pursue your plan - and delay your opponents plans. Bonus points for moves that do both.
Take your time for this - it will help you find a plan OTB if you practice it.

At higher ratings games are usually decided by strategy, not tactics. While it is important to have a good eye for tactics, tactical opportunities will be rarer and rarer. Get a good position, keep a good position and the checkmate will come naturally! :)


I have experience with only SunFish, but I doubt it's 2500+ level.

  http://talkchess.com/forum3/viewtopic.php?f=2&t=67025

This link should help you. If you're not happy with the folks at talkchess, you probably won't find a better answer anywhere else.


What is the earliest possible age to start teaching children how to play chess?

Depending on several factors, the age to start teaching a child to play chess can vary.

The mere fact that she asked you how she can play chess is a good sign that she is interested in learning.  Interest is one of the key factors because we don't want to force-feed them the game.  If I had to pick an age, I would say 4 is a good age, but it depends also on maturity.  I would also say not to expect too much and let her have fun. A great place to start is http://wwww.chesskid.com

My 2 (almost 3 year old) stumbled upon Chessmaster by accident.  He was more intrigued by the movie type intro to the game rather than the actual game itself, nevertheless, he remained interested and knows all the names of the pieces, but that is about it.  He knows that it is a game, but if I tell him something like "Take the knight", he will take a pawn on some square and go all the way across the board and take it, lol, so based on my own experience, 3 seems to be too young in most cases.  I have really yet to see 4, but when my kid reaches 4, I guess I will find out, but based upon his reaction now, I think he would have a good grasp of the rules by age 4, maybe earlier.  As for now, I just let him have fun.


Why is this king and two passed pawns vs. king and rook endgame not drawable?

There is no absolute result for this type of endgame-it all depends on the position of the pieces. In fact, any result is possible.

Objectively, this particular position with black to move is a loss-you didn't make a mistake.I suggest you consult endgame tablebase, which announce a loss in 24 moves with best play by Black. Here is an example line.

[FEN "8/1R6/8/5pp1/3K1k2/8/8/8 b - - 0 1"]

1... g4 2. Kd3 Kf3 3. Kd2 g3 4. Ke1 Ke3 5. Rb3+ Kf4 6. Kf1 Kg4 7. Kg2 f4 8. Rb4 Kf5 9. Kf3 Ke5 10. Rxf4 Kd5 11. Kxg3 Ke5 12. Kf3 Kd5 13. Re4 Kc5 14. Re5+ Kd4 15. Rf5 Kc3 16. Rf4 Kd2 17. Rd4+ Kc2 18. Ke2 Kc3 19. Re4 Kb2 20. Kd2 Kb3 21. Rd4 Kb2 22. Rd3 Ka1 23. Rb3 Ka2 24. Kc2 Ka1 25. Ra3#

In the game, the White king is able to get and front of the Black pawns after Black tries to push them for promotion. White is then able to scoop them up as Black attempts to defend them with their king. Once Black is down to their king, it is a simple king and rook endgame for White. Win.

Some nice online resources about this endgame type:

General ideas and examples

More general ideas, examples and statistics

Real games collection


Why do Grandmasters play different openings but engines not?

Engines

Engines usually have opening databases. Every variant in each opening has a pre-calculated score and according to the opponent's move, engines will choose highest scored move. So, sometimes you may feel they play as same as previous games.

But, that's not all, many good engines will choose a random move among a group of best candidate moves because their programmers don't like biased engines.

Grandmasters

On the other hand, grandmasters, they know lots of openings and they're incredibly skilled on some of them. Sometimes they persist on a specific opening to learning more. Sometimes they play different openings against opponents to make them surprised or confused.

Head-to-head matches between two grandmasters usually lead to a little number of openings. Because the white player tries to choose an opening based on his power and opponent's weakness.


What are all of the possible tags for PGN?

PGN standards are described here. There are seven more-or-less required tags:

[Event]
[Site]
[Date]
[Round]
[White]
[Black]
[Result]

and many different supplemental tags, for example [WhiteElo] and [BlackElo] for the players' ratings, [Board] for the board number in team events, and [TimeControl] for information about the time-control used.


Should I accept doubled pawns to remove the opponent's bishop pair advantage?

In general, the two bishop advantage is worth half a pawn, while double pawns are only a minor disadvantage. Sometimes doubled pawns can be an advantage if they do not block your pieces and control important squares. OTOH, creating doubled isolated pawns on a half open file is likely to be worth the loss of a two bishop advantage.

Long term imbalances that occur early in a game are easier to deal with than those that occur late in a game. Let us take for instance the Nimzo-Indian line

[FEN ""]

1.d4 Nf6 2.c4 e6 3.Nc3 Bb4 4.a3 Bxc3 5.bxc3 c5 6.e3 O-O 7.Bd3 d5 8.cxd5 exd5

Black has just allowed white to undouble the pawns that he gave up his dark square bishop to double. The key to understanding this is that the doubled pawns are not such a big deal. Black is looking to keep white's dark square bishop permanently bad (because of the pawns on e3 and d4), while getting good squares for his knights. Black's light square bishop will be not so bad (still bad because of the d5-pawn) and will also look for opportunities to trade his light square bishop for white's.


How to limit the depth of analysis in Arena?

What you want to do is limit the number of cores Stockfish has access to. I'm sure your computer/laptop has more than one core, but if improperly set, a UCI engine can eat up all of your processing power and leave your computer sluggish. There are two ways to fix this.

Arena should have a "Lower than normal process priority" in Engine Management Options. You should check this off.

Also, I know Chessbase lets you allocate a certain amount of cores (or threads) for the engine, and I'm sure Arena does as well. However, I'm not entirely sure how to do it with the specified software.


What is the longest professional chess game that ended in a checkmate?


Best software I've ever seen for this purpose: CT-Art from Convekta. It's amazing. It's based on Blokh's tactical manuals, gives you positions to solve, and hints when you fail to solve them. And it's cheap (I've seen it new for $20 or so).

Best. Tactics. Software. Evar.


The chief arbiter is in practice no different from a standard arbiter - it is more a convenience in tournament organization.

In many tournament there are so many players that it is necessary to have several arbiters, and of those usually the one with the highest title (often IA for professional or large tournaments) is considered the 'chief' arbiter who is responsible as arbiter for all purposes that concern FIDE, etc. and to whom all other arbiters report. This also allows for less experienced arbiters to be used where necessary, as disputes with a less experienced arbiter (unlikely, but possible) can then be taken to the chief arbiter.


Is there any game where AlphaZero wins against Stockfish thanks to a knight pair?

I found a game in which AlphaZero wins the game mostly due to the major activity of the knights in the middlegame.

Jeremy, from ChessNetwork, made a great anaylsis on the game.

[Title "AlphaZero-Stockfish, London England, 2017"]
[FEN ""]

1. d4 Nf6 2. c4 e6 3. Nf3 b6 4. g3 Bb7 5. Bg2 Bb4+ 6. Bd2 Bxd2+ 7. Qxd2 d5 8. O-O O-O 9. cxd5 exd5 10. Nc3 Nbd7  11. b4 c6 12. Qb2 a5 13. b5 c5 14. Rac1 Qe7 15. Na4 Rab8 16. Rfd1 c4 17. Ne5 Qe6 18. f4 Rfd8 19. Qd2 Nf8 20. Nc3 Ng6 21. Rf1 Qd6 22. a4 Rbc8 23. e3 Ne7 24. g4 Ne8 25. f5 f6 26. Nf3 Qd7 27. Qf2 Nd6 28. Nd2 Rf8 29. Qg3 Rcd8 30. Rf4 Nf7 31. Rf2 Rfe8 32. h3 Qd6 33. Nf1 Qa3 34. Rcc2 h5 35. Qc7 Qd6 36. Qxd6 Rxd6 37. Ng3 h4 38. Nh5 Ng5 39. Rf1 Kh7 40. Nf4 Rdd8 41. Kh2 Rd7 42. Bh1 Rd6 43. Ng2 g6 44. Nxh4 gxf5 45. gxf5 Rh8 46. Nf3 Kg7 47. Nxg5 fxg5 48. Rg2 Kf6 49. Rg3 Re8 50. Bf3 Rdd8 51. Be2 Rf8 52. Bg4 Nc8 53. Bf3 Rfe8 54. h4 Rh8 55. h5 Rhe8 56. Bg2 Ne7 57. h6 Rh8 58. Rh3 Rh7 59. Kg1 Ba8 60. Nd1 g4 61. Rh5 g3 62. Nc3 Ng8 63. Ne2 Rxh6 64. Nxg3 Rxh5 65. Nxh5+ Kf7 66. Kf2 Nf6 67. Nxf6 Kxf6 68. Rh1 c3 69. Rc1 Rh8 70. Rxc3 Kxf5 71. Rc7 Kf6 72. Bf3 Rg8 73. Rh7 Rg6 74. Bd1 Rg8 75. Rh6+ Ke7 76. Rxb6 Kd7 77. Rf6 Ke7 78. Rh6 Rg7 79. Rh8 Bb7 80. Rh5 Kd6 81. Rh3 Rf7+ 82. Ke1 Bc8 83. Rh6+ Kc7 84. Rc6+ Kb8 85. Rd6 Bb7 86. b6 Ba6 87. Rxd5 Rf6 88. Rxa5 Rxb6 89. Kd2 Bb7 90. Rb5 Rf6 91. Bb3 Kc7 92. Re5 Ba6 93. Kc3 Rf1 94. Bc2 Rh1 95. a5 Kd6 96. e4 Bf1 97. Rf5 Bg2 98. Rf4 Rc1 99. Kb2 Rh1 100. a6


Analysis of a very complicated end position - why is this move leading to a draw?

The reason why you lose the winning edge is, as it almost always is, because of tempi:

[fen "8/4Kp2/4p3/4k1p1/8/8/5PP1/8 b - - 0 1"]

1...f5? 2.Kf7, g4 3.g3!, Kd6 4. Kg6! (4.Kf6?, Kd5 5. Kg6, Ke4! 6.Kf6,  e5 7.Kg5, Kf3 {and black picks up the f2 pawn.})
4...Kd5 5. Kf6 {and black cannot advance without giving up a vital pawn.}

Let's look at what happens when playing ...f6 first:

[fen "8/4Kp2/4p3/4k1p1/8/8/5PP1/8 b - - 0 1"]

1...f6 2.Kf7, g4 3.g3 (3. Kg6, f5! 4. Kf7, {For 4. g3, see the variations above; it's a transposition.} 4...f4 {and white is helpless against the black pawns.})
3...Kf5 4.Ke7, e5 5.Kf7 (5.Kd6, Ke4! 6. Ke6, f5 {and white is toast.})

5...e4 6.Ke7 (6.Kg7, Kg5!) 6...Ke5! {denying the white king access to the action.} 7.Kf7, f5 8. Kg6, f4 {and black breaks through.}

So basically what happens is that ...f6 loses a tempo on purpose, to deny white the blockading idea available after ...f5. It's not easy to see immediately, but it's worth noting, as ideas like manipulating tempi in pawn endgames is the key to playing them successfully. Remember this in your next pawn endgame, as it could gain you an extra half point.

So, what about ...Kf5? It also wins:

[fen "8/4Kp2/4p3/4k1p1/8/8/5PP1/8 b - - 0 1"]

1...Kf5 2. Kxf7 (2.f3, g4!? 3. Kxf7, e5 4. Kg7 (4.Ke7, g3! 5. Kd6, e4 {and black breaks through.}) 4...Kf4! 5.Kf6, g3! 6. Kg6, Ke3! {and black picks up g2 and the victory.}) 2...e5 3.Ke7, e4! (3...g4? 4.g3!, e4 5.Kf7!, e3 6.fxe3, Ke4 7.Kf6, Kxe3? 8.Kg5, Kf3 9.Kh4 {and white wins. Oops!})
4.Kd6, g4 5.Kd5, g3 {and black wins.}

These lines aren't exhaustive, but I think that I've outlined the most important variations.

With this I hope that I've been able to show that in pawn endgames, general principles only serve to guide you. You must calculate precisely!


Who is the teacher of the game that has a lesson plan as follows:

Not in 3D and not super-fancy, but it should get across the point. I did not do it for the rook because as you note the rook always has 14 squares to go to (on an empty board).

However if you want to use this to argue for putting pieces in the center, I'd be careful, because:

This is for an empty board. Lots of things can happen when other pieces are on the board.
The illustration for the king is probably of limited value because (unless you are Steinitz) we don't usually think of the king as an active piece.
For the queen and bishop (which are essentially the same, only shifted by 14, the number of rook moves) you notice that the difference between different squares (center and border) is not all that great. In my opinion a much more important factor for positioning queen and bishop centrally in a real game is that they have more options, i.e. a bishop in the center can go in four directions while a bishop in the corner has only one direction. This means that a bishop in the center can attack things in all four directions and likewise in order to block this bishop, the opponent has to block four directions. Also for transferring the bishop to other parts of a board a central position might be better.
For the knight there could be some value in this as it cannot be blocked by other pieces, so the situation for a knight is essentially the same as on an empty board. That's where you get the saying: "A Knight on the rim is dim" from. But as with all such rules there are plenty of exceptions.


There are quite a lot of basic principles. Whole books have been written on the principles of strategic play, for example. Basis rules are useful and will get you on your way. For more advanced players it is actually more important to understand when to break the rules.

A couple of rules 'off the top of my head':

A knight on the rim is dim, meaning that it's better to keep your
knights centralised than to put them on the edge of the board.
Loose Pieces Drop Off (LPDO), meaning that unprotected pieces are
vulnerable to (double) attack. So keep your pawns and pieces
protecting each other.
The side with less space should exchange pieces (and vice versa).
The side with an advantage should attack, or he risks losing his advantage.
If you have a choice in captures with pawns (say h2xg3 or f2xg3), capture towards the center.
Try to avoid weaknesses in you pawn structure (isolated pawns, doubled pawns,
backward pawns).
Invite everybody to the party, meaning activate all your pieces especially when attacking the enemy king.
Don't make pawn moves on the side of the board where you are weaker.
Etc, etc.

Remember that for every rule above there are a lot of exceptions.

For the endgame:

Activate your king
Improve your position to the maximum
When you have the advantage, try to create a second or third weakness
In rook endings activity (of king and rook) is usually more important than one or two pawns
Opposite colored bishops endings have a large drawing tendency
Knight endings have a lot in common with pawn endings
In queen endings it's more important how far your passed pawn has advanced, than how many passed pawns you have.
Etc, etc.

When studying chess you will gather a lot of these rules.


Are there any hypermodern openings for white

A hypermodern opening in chess is one whose strategy controls the centre from the outside. For instance fianchettoed bishops [b3 or g3 followed by Bb2 or Bg2] can do this. Central pawn moves are delayed till later on.

Specifically a hypermodern opening for white could be 1. b3 and then 2. Bb2 called Larsen's Opening or the Nimzowitsch attack. The idea is to use the Bb2 bishop along its diagonal, especially if black castles kingside. For instance the opening could go:

  [FEN ""]
  1. b3 e5 2. Bb2 Nc6 3. e3 d5 4. Bb5 Bd6 5. f4 Qh4+ 6. g3 Qe7 *

This is quite a well known opening position in Larsen's attack. White's move 5. f4 is important - white is attacking black's centre. A common continuation is for white to eventually castle o-o-o queenside and black to castle kingside with equal chances of mutual attack. Larsen was a GM who used this opening with great success with one exception! His loss to Spassky: http://www.chessgames.com/perl/chessgame?gid=1128831

Another hypermodern opening is to play 1. Nc3 and 2. Nf3 as white and provoke black into chasing your knights with black's pawns. This is rather humorously called the Napoleon attack after Napoleon's horses!! Though I am pretty sure that he never played it!

Another hypermodern opening is the King's Indian Attack - a King's Indian formation as white:

   [FEN ""]
   1. Nf3  Nf6  2. g3 d5 3. Bg2 c5 4. d3 Nc6 5. O-O e5 6. Nbd2 Be7 7. e4 O-O 8. Qe2 *

Fischer used this with success. There are many hypermodern white openings that let black put pawns in the centre to make a target for white to attack. This is a small taste of them here.


Improving the observation skill & making less blunders

I will go back to what Artur Yusupov, three-time World Championship Candidate, former top-10 player,  and one of the greatest living trainers recommends in the first book of his 10-volume series. In volume one, "Boost Your Chess - Build Up Your Chess", chapter 9, which is two-move mates, including composed problems:

  The aim of this lesson is to improve your calculation of short
  variations. It is more important to find a lot of options in the
  first few moves than to calculate moves long variations. Most mistakes occur in the early moves in variations. What
  is the use of calculating a long and correct variation if your
  opponent has a much better reply on move one?

  You must develop your skill at calculating short variations, while at the same time taking into account the possibilities available to
  your opponent. This skill should reduce blunders.

  Exercises with mate in two moves are very well suited for training in
  the art of calculating short variations with great accuracy.
  Emphasis as written, not mine.

I will take this one step further with my own suggestion. Try to train yourself that before you make every move, look at EVERY move your opponent has. I am not saying that you are calculating anything. You are simply looking at it so you consider it. It will do two things: If you are hanging a piece, just looking at it will usually "hit you in the face like a brick", and second, I have done many combination problems over the last 40 years, and sometimes, when I cannot figure it out, and look at the answer, I realize immediately that had I just LOOKED at the move, I would have seen the combination.

So, again, you are not trying to calculate, just consider every move. You will be amazed at what you register immediately.


Can I reply to an illegal move with checkmate?

Yes. Putting your own king into danger is considered an illegal move. Depending on the context, illegal moves can be treated in different ways:

In most casual games, players just agree to roll back to the position before the illegal move was made.
In tournament games, the player who didn't make the illegal move gets 2 extra minutes on the clock. I guess this does not apply, as most likely you aren't playing with a chess clock. Anyway, the second illegal move is punished with a loss

Since you're playing a casual game with your brother, just go for the one you agree on!


Where are the opening trends heading at the start of the decade?

With e4, a few that come to mind are the Rossolimo Sicilian, often to avoid Magnus' Sveshnikov, and the Najdorf never goes away. The Italian game, and the Ruy Lopez is another that never goes away (Magnus has 180 games as white alone with it).

With d4, the Catalan is still popular along with the various Queen's Gambit lines.

Obviously, very few things every go totally out of style unless they are totally busted, but to come up with the list, I used ChessBase to do "dossiers" on Carlsen, Caruana, Ding, and So; and then I looked at what they played the most, and ignore openings with lesser quantities of games. They seem to mostly play very traditional openings that take direct control of the center.

EDIT: First, I think that the Berlin was on a level all by itself due to Kramnik's successes, and because every top player plays 1...e5 a lot, and because the Ruy Lopez is so difficult to defend. I just finished watching "The Method in Chess" Videos literally just yesterday, and in one of the last two, GM Dorfman made a comment about how the Ruy is just "statically worse", and that black is mostly confined to the last three ranks, and white can choose to play on the kingside, center, or queenside, meaning that black always has to be that much more vigilant about white's intentions in any of the three areas. The Berlin solved that at the cost of a slightly inferior endgame, and thus, it solved it for A LOT of elite players. Therefore, it also got played a lot more often than most other opening trends.

I looked through my New in Chess Yearbooks, which are basically surveys of opening theory, and it mostly confirmed what I wrote above. Here is a list of players, who have played each of the following openings.

What I did to get this information was plug in the position I knew was popular from reading about chess over the last few years, and the Yearbooks, and then clicked on the Reference Database (Mega 2020) in ChessBase, and then sorted by ELO rating, and paged down to see what elite players played it. If they played it just once or twice, I did not include them. Nakamura was on the edge for a few of them, but I noted that.

Rossolimo with white: Carlsen, MLV, Aronian, Nakamura, Anand, Caruana, and Giri. I sorted the following search to bring up Carlsen's games as black to show how they are trying to avoid his Sveshnikov (far right in the picture), but he also has played it against Radjabov, Gelfand, and Dubov, among others.

Sveshnikov as black: Carlsen, Caruana, Grischuk, and Radjabov.

Najdorf as black: Carlsen, MLV, Ding, Grischuk, Anand, Giri, Grischuk, and again, Nakamura dabbles.

The Italian Game with white: Carlsen (19 games), Caruana, Ding, So, MLV, Giri, Anand, Karjakin, Nepo, Aronian, and even Nakamura has played it a few times.

The Ruy Lopez with white, and all have played it A LOT...more than any other opening I could find: Carlsen, Caruana, So, MLV, Anand, Topalov (even as recently as 2015), Anand, Giri, and Nakamura some.

As you can see, while the top players may avoid one of the above, they are all very popular overall.


Should playing chess against yourself always end up in a draw?

No.

When you are playing seriously against yourself, you still have to commit to moves. After making the move you start analysing again and see things you previously have not seen, and you may discover an error in the moves you have already made and the game becomes a win for one of the sides you play.

Or you may find a winning way without really catching an error in the previous moves.

Note that there are no secret plans in chess, the full truth is always on the board. It is up to you to read the board and draw the best consequences of that reading.


Is it possible to play the Najdorf Defense if white played 1. d4?

If White starts with 1.d4 it is possible to reach a Najdorf position, for example:

[FEN ""]
1.d4 d6 2.e4 c5 3.Nf3 cxd4 4. Nxd4 Nf6 5. Nc3 a6

However, White has other moves on move 2, which still give them an advantage: 2. c4 and 2.Nf3, also White could play 3. c3. So Najdorf is not that easy to get. Moreover, some people play 1.d4 to avoid Sicilian and especially Najdorf; they will certainly not follow the above line.


Visualization training is visualizing moves on the board WITHOUT looking at the board, like:

Tell all the squares controlled by a knight on d4
All the shortest paths to move a knight from a3 to h8
How a Qa5 can attack a Rh4 without being captured
How a Nc4 can check a Kb7 defended by Bb6 without being captured

etc., etc.

you might laugh and think it is easy, but it is not. Try a series of them randomly created and write down your answers then compare them to what you see while looking at the board.

Fun stuff.

Purpose?
It makes you a better calculator when looking at positions during your game. You will eventually instantly see multi-move paths that pieces can take across the board, especially knights.


My chess AI makes the same repeated moves

Unfortunately, the only right answer to "How do I eliminate this scenario" is "fix your algorithm."  Yes, you could implement the 3-fold repetition rule, but you should also figure out what it tells you about your algorithm.

This sort of repetition happens when there is an oscillating pattern that arises in your scoring.  Think of it like rock paper scissors.  White makes move to try to achieve a rock position, so black tries to make a counter-move that turns it into a paper position.  Then white tries to create a scissors position and black replies by creating a rock position.

The only way to fix this is to look at your algorithm, and make the algorithm better.  My advice is to put your chess program into a debug mode and have it dump out an analysis of what it is "thinking" with each move.  Look at the factors which lead up to your final score, and understand how they're acting.

Once you understand why the algorithm is doing what it's doing, you can fix it.  Look at the game and decide what move you'd rather see them do, and why you like that move.  See if you can add additional scoring which encourages the type of play you want to see.

One thing in particular I've seen that can cause this sort of behavior is a discontinuity on the horizon.  If your scoring stops at your ply limit, and that position looks good from black's perspective, looking one ply further may show a good position for white instead!  This, of course, will always happen in real life, but you can try to minimize how often it happens by doing a better job of scoring each position.

If all else fails, a little randomness can help nudge the game along.  One mode I implemented when I had to write one of these programs was a variable depth algorithm.  Sometimes it would look at 100,000 positions before making a decision, other times it might make 200,000.  That decreased the probability that I would run into a simple issue just past my horizon, because my horizon kept moving.  Instead, I might blunder into the bad move, but at least the game moved forward!


Indeed, there are many possible positions in which all mates are forced on the first ply. Since you ask not for that, I shall provide examples with more than one move by both sides.
Here is the known, and overall, length record for both sides having multiple legal moves since you said that a single line "isn't too satisfying."
[Title "Alexey Khanyan, Tim Krabbe's Website Diary Entry #267 2008, Mate In 11 Moves/22 Plies"]
[FEN "4Q2Q/4r3/4n1n1/1bbK1krn/RR1RR1RR/2qn1R1n/4n1nN/Q3Q3 b - - 0 1"]
[startflipped ""]

1... Ng2f4+ 2. Rfxf4+ N2xf4+ 3. Rgxf4+ Nh3xf4+ 4. Rhxf4+ Ndxf4+ 5. Rxf4+ Nhxf4+ 6. Rxf4+ Ngxf4+ 7. Rxf4+ Nxf4+ 8. Rxf4+ Kxf4+ 9. Qee5+ Qxe5+ 10. Qaxe5+ Rgxe5+ 11. Qxe5+ Rxe5+ 12. Qxe5#

Source: Diary Entry #267
Additionally, I know of this simple problem that illustrates it with either playing giving mate.
[Title "Eugene B. Cook, The Chess Amateur 1926, Mate In For White And Black"]
[FEN "Bk6/1P6/1P3p2/8/8/2P3p1/6p1/6Kb w - - 0 1"]

Lastly, be sure to check out a funny mutual zugzwang position in this CSE question by the user @Peter, in which both sides are forced to let the other mate them!


Should I play a risky combination when I don't see the refutation?

It depends on how well you like your chances without the combination.

If, taking everything into account (material, position, opponent's rating, etc.), you are likely to win the game in the normal course of events, then play it safe.

On the other hand, if you have lost material, or are in a bad position, or your opponent is rated much higher than you, take a chance.


Move-order issue in the Grunfeld: ...Nc6-a5 vs ...Nc6-e7

Analyzing this position it seems like the N to the rim has potential issues getting back into the game. W will play b3 and both of the black N's on the Q side are very limited.

After Ne7 the N gets back into the game via c8 and d6 playing an important role blockaiding the p at d5.

That is the best I could find. Transposing to the same position did not come up in my analysis so maybe I am missing something.


Why do most beginners play this line agains the Caro-Kann?

It's not the best way to play against the Caro-Kann, but it's good enough for beginners. It follows basic opening principles: develop your pieces, fight for the center, knights before bishops, though it does violate the rule about moving a piece (or pawn?) more than once. It's true that the Knight on c3 blocks the natural c4 advance, but beginners can't be expected to know that (see below).

If you're seeing this a lot from opponents, don't worry. It will go away (but not completely) as your rating improves and you start playing stronger players. Beginners are commonly told not to study openings, which they interpret to mean don't even learn the first 3 or 4 moves.


Is computer chess exhibiting the predicted "draw death"?

For what it's worth, here are the rates of decisive games of the TCEC seasons 4 'til 8 superfinals. Season 4 is a bit of an outlier (maybe a rule change?), but after that the percentage of decisive games drops consistently.

Season 4: 10/48 = 20%

Season 5: 18/48 = 37%

Season 6: 19/64 = 30%

Season 7: 11/64 = 17%

Season 8: 11/100 = 11%

Arguably at an even higher level are the games in correspondence chess which are played with engine assistance. I'm too lazy to count all the decisive games in the recent decades of the correspondence world championships, but in 2003 the rate of decisive games was 32% while in 2013 (two games still running) the rate has declined to 12%.

2003: 34/105 = 32%

2013: 17/134 = 12%

These numbers indicate that there is a draw death in chess, somewhere north of 3200+ Elo.


Quickly converting board to bitboard representation using python-chess library

python-chess already has the built in utilities to handle conversions. Here is an example:

import chess

board = chess.Board('rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1')

WP = board.pieces(chess.PAWN, chess.WHITE)
BP = board.pieces(chess.PAWN, chess.BLACK)

print (int(WP), int (BP))

print (list(WP), list(BP))

print ("\nWHITE PAWNS:\n" + str(WP))

print ("\nBLACK PAWNS:\n" + str(BP))

Output:

65280 71776119061217280

[8, 9, 10, 11, 12, 13, 14, 15] [48, 49, 50, 51, 52, 53, 54, 55]

WHITE PAWNS:
. . . . . . . .
. . . . . . . .
. . . . . . . .
. . . . . . . .
. . . . . . . .
. . . . . . . .
1 1 1 1 1 1 1 1
. . . . . . . .

BLACK PAWNS:
. . . . . . . .
1 1 1 1 1 1 1 1
. . . . . . . .
. . . . . . . .
. . . . . . . .
. . . . . . . .
. . . . . . . .
. . . . . . . .

From a list, or from an integer, you can easily construct a Bitboard however you choose to define it.