Comment by cool_dude85
1 year ago
>Chess is stateless with perfect information. Unless you're going for mind games, you don't need to remember previous moves.
In what sense is chess stateless? Question: is Rxa6 a legal move? You need board state to refer to in order to decide.
They mean that you only need board position, you don't need the previous moves that led to that board position.
There are at least a couple of exceptions to that as far as I know.
Yes, 4 exceptions: castling rights, legal en passant captures, threefold repetition, and the 50 move rule. You actually need quite a lot of state to track all of those.
It shouldn't be too much extra state. I assume that 2 bits should be enough to cover castling rights (one for each player), whatever is necessary to store the last 3 moves should cover legal en passant captures and threefold repetition, and 12 bits to store two non-overflowing 6 bit counters (time since last capture, and time since last pawn move) should cover the 50 move rule.
So... unless I'm understanding something incorrectly, something like "the three last moves plus 17 bits of state" (plus the current board state) should be enough to treat chess as a memoryless process. Doesn't seem like too much to track.
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The correct phrasing would be is it a Markov process?