  Polar codes, invented by Arikan in 2009, are known to achieve the capacity of
any binary-input memoryless output-symmetric channel. One of the few drawbacks
of the original polar code construction is that it is not universal. This means
that the code has to be tailored to the channel if we want to transmit close to
capacity.
  We present two "polar-like" schemes which are capable of achieving the
compound capacity of the whole class of binary-input memoryless
output-symmetric channels with low complexity.
  Roughly speaking, for the first scheme we stack up $N$ polar blocks of length
$N$ on top of each other but shift them with respect to each other so that they
form a "staircase." Coding then across the columns of this staircase with a
standard Reed-Solomon code, we can achieve the compound capacity using a
standard successive decoder to process the rows (the polar codes) and in
addition a standard Reed-Solomon erasure decoder to process the columns.
Compared to standard polar codes this scheme has essentially the same
complexity per bit but a block length which is larger by a factor $O(N
\log_2(N)/\epsilon)$, where $\epsilon$ is the gap to capacity.
  For the second scheme we first show how to construct a true polar code which
achieves the compound capacity for a finite number of channels. We achieve this
by introducing special "polarization" steps which "align" the good indices for
the various channels. We then show how to exploit the compactness of the space
of binary-input memoryless output-symmetric channels to reduce the compound
capacity problem for this class to a compound capacity problem for a finite set
of channels. This scheme is similar in spirit to standard polar codes, but the
price for universality is a considerably larger blocklength.
  We close with what we consider to be some interesting open problems.
