6 ms·
> Black to move, and in the final position, the pawn at h4 can be captured en-passant. > They're all legal. But then, looking at the final position[1], black
by Fang_ 5y ago
> Black to move, and in the final position, the pawn at h4 can be captured en-passant.
> They're all legal.
But then, looking at the final position[1], black is in check by the knight on b2. If white's pawn can be captured en passant, this implies the knight was not the most recent move, so the black king was in check on the previous turn as well.
It's obviously not legal to remain in check. What am I missing?
[1] https://raw.githubusercontent.com/tromp/ChessPositionRanking/72608cf14906b989753024810fc642142605cca5/img/8686186724060380137654941364776065067846290128.png https://raw.githubusercontent.com/tromp/ChessPositionRanking...
- tromp 5y agoTo quote from Seinfeld: "It's not you. It's me" I missed something, and clearly misclassified this position, leaving only 51 legal in the 1k set (and only 537 in the 10k set). Oops. It's embarrassing since I did pay attention to the en-passant positions in the 919-93 positions not from the smaller 1k sample, such as this one: https://github.com/tromp/ChessPositionRanking/issues/916 https://github.com/tromp/ChessPositionRanking/issues/916 I'll have to make some changes to my README. Meanwhile, congratulations on spotting the error. And I'll be sure to mention you in the eventual publication. This underscores the need to back up my classification with proof games...
- tromp 5y agoAs I went to look for the corresponding issue, I was surprised to not find the position among the open issues. In fact it was closed as https://github.com/tromp/ChessPositionRanking/issues/915 https://github.com/tromp/ChessPositionRanking/issues/915 So I had classified it correctly, but only AFTER making the diagrams for the 1k sample. That means the 538 count for the 10k sample still stands. Good. Less things to fix on the README :-)
- tromp 5y agoA misclassified issue was found by Github user 1pab42 at https://github.com/tromp/ChessPositionRanking/issues/878 https://github.com/tromp/ChessPositionRanking/issues/878 That changes the prospective number of legal positions to 539...
- tromp 5y agoBut just today github user @mcdallas found another position misclassfied as legal [1], so the two misjudgements cancel out and the original 538 count currently still stands. Lovely:-) [1] https://github.com/tromp/ChessPositionRanking/issues/794 https://github.com/tromp/ChessPositionRanking/issues/794
- tromp 5y agoPeter Osterland found yet another misclassification in https://github.com/tromp/ChessPositionRanking/issues/824 https://github.com/tromp/ChessPositionRanking/issues/824
- tromp 5y agoAnd another at https://github.com/tromp/ChessPositionRanking/issues/476#issuecomment-922351740 https://github.com/tromp/ChessPositionRanking/issues/476#iss...
- tromp 5y agoAnd another at https://github.com/tromp/ChessPositionRanking/issues/111 https://github.com/tromp/ChessPositionRanking/issues/111
- tromp 5y agoAnd yet another at https://github.com/tromp/ChessPositionRanking/issues/186 https://github.com/tromp/ChessPositionRanking/issues/186
- tromp 5y agoGithub user @Ananas1729 (Ben Jones) found another at https://github.com/tromp/ChessPositionRanking/issues/243 https://github.com/tromp/ChessPositionRanking/issues/243
- jancsika 5y agoWhy isn't it legal to remain in check?
- hypertele-Xii 5y agoThe rules of Chess say so. Duh.
- jancsika 5y agoHa! It's funny-- except for Tenoke all the responses so far boil down to essentially this. I'll try again. Assume an alternate reality where this incredibly important rule doesn't exist. In it, the other player simply takes the king on the next turn from a neophyte who didn't realize they are still in check. What bad things would happen as a result of the non-existence of the gratuitous rule? And don't just speculate based on the zero cost of posting on HN. Give me the real reason based on the history of the creation of chess rules and/or the documented behavior of real chess players in history.
- tromp 5y ago> Assume an alternate reality where this incredibly important rule doesn't exist. In it, the other player simply takes the king on the next turn from a neophyte who didn't realize they are still in check. This is not merely an alternate reality; this is effectively the reality of blitz chess, where capturing the king is a way of claiming victory by declaring that the opponent made an illegal move when they didn't move out of check. In blitz chess you do not have the right to correct illegal moves after the opponent points them out. https://www.reddit.com/r/chess/comments/jrvmk7/capture_the_king_in_blitz/ https://www.reddit.com/r/chess/comments/jrvmk7/capture_the_k...
- deleted 5y ago[deleted]
- jancsika 5y agoI feel as if I'm being gaslighted. If the penalty for the specific illegal move of not getting oneself out of check is to lose the game, what could the practical significance of the rule possibly be? The other respondent is claiming that chess would become a game of "gotcha," as if the rule somehow prevents chess players from faking injuries to distract the chess ref and get free moves.