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- Hacker News
- If you like this, you're probably gonna like this: https://en.wikipedia.org/wiki/Chessboard_complexby unprovable
- > It is a concurrent system, but with a very specific kind of concurrency: interleaved execution. More specifically, taking turns: white, then black, then white.
"Chess is a game of imperfect information, but with a very specific kind of imperfectness: fully available information. More specifically, ever single information is visible: you see all your opponents' pieces and he sees all yours, you see how much time he's got left, and he sees how much time you have left".
Who knew it? Chess is actually a concurrent game of imperfect information: with that definition, it's not unlike a real-time strategy game like Warcraft 3.
Who would have guessed it?
- So many of these invariants are redundant and so few of them encode any of the interesting rules of chess.
- > apparently it wasn't until 19th century that people made clear that you couldn't promote a pawn to a King, surprising an attempted checkmate by responding Le roi est mort, vive le roi!
That's the coolest thing ever though, why would you ban such a move, where's the rule of cool when you need it most?
by stymaar - Shameless plug: a code walkthru modeling the rules of chess, ment as an exercise/teaching functional programming (in Clojure):
https://neuroning.com/boardgames-exercise/notebooks/walkthro...
The implementation makes it really easy to add new piece types or rules. For example, here's the full logic for rooks (sans castling):
(defn expand-pmove-for-rook [pmove] (->> pmove (expand-pmove-dirs [↑ ↓ ← →]) (pmoves-discard #(or (pmove-on-same-player-piece? %) (pmove-changed-direction? %))) (map pmoves-finish-capturing-opponent-piece) (pmoves-finish-and-continue))))by ferd - > Chess is a lot trickier than it looks. It has so many rules: castling, en passant, pawn promotion, pinning, the discovered check, and the deadlock case of stalemate.
Nit: Pinning and the discovered check are not really rules, but rather names of tactics.
by yewenjie - The historical rules also left ambiguous promotion to the opposite color: https://chess.stackexchange.com/questions/8291/pawn-promotio.... This rule was clarified later to restrict to the same color.by sobellian
- > Chess is a lot trickier than it looks. It has so many rules: castling, en passant, pawn promotion, pinning, the discovered check, and the deadlock case of stalemate.
As a kid playing chess with other neighborhood kids back in the day, absolutely none of us even knew about the en passant rule. My first exposure around the same time was completely by accident thanks to a passing reference in a CRPG called Betrayal at Krondor. It comes up in a story about a game that nearly costs an innkeeper her establishment when she loses because of a move she didn’t even know existed.
by vunderba