Questions tagged [illegal-move]
A move that doesn't respect the rules of chess.
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How to detect an illegal position?
There are many positions in chess that are illegal in the sense that they cannot be reached by legal moves.
Is there an algorithm to detect if a position is illegal or not?
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Are there any illegal positions that are difficult to spot?
I have a question and I'm sorry if it sounds very uninformed, I'm not a professional chess player so my interest is mere curiosity. I was wondering if there are examples of illegal positions that ...
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Official knight move rule definition
Not a trivial question: How would you define the knight move rule on a d-dimensional chessboard (say an 8 X 8 X ... X 8 board) by extending the official knight move rule that states how a knight moves ...
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Illegal move or forfeit on time - who wins this 5-minute match?
In a 5-minute match a player makes an illegal move leaving his king in a check position. This usually gives the victory to the opponent, if he sees it and captures the king.
Otherwise, if the opponent ...
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How often do strong master level players (2400+) make illegal moves?
In the latest podcast from the Chicken Chess Club, Laurent Fressinet admitted that in his latest tournament, the French rapid and blitz championships, he made an illegal move. He asked the other two ...
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Ignoring Touch Move results in an Illegal Move?
I just wanted to clarify the following incident:
When touching a piece without expressing the intend to adjust its position (cf. 4.2.1 FIDE Laws of Chess), such that it has to be moved because there ...
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Is there a website that records the moves of a chess game in video or gif format, and also allows illegal moves?
I've wanted to record some chess games in 2d video or gif form from a version that I made that has different rules, but it won't allow me to import it because it has illegal moves. Is there a way to ...
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Term to distinguish between two categories of illegal positions
Consider these two categories of illegal positions. First, e.g.:
Not having exactly one King of each color
Both Kings being in check
Pawns on the first or eighth ranks
Second, e.g.:
Having more ...
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Can someone press the clock without making a move to avoid getting flagged in 2022?
As the title says let's say it is a 1 hour 30 minute game with 30 seconds increment/move. Now if someone deliberately presses the clock at the last second without moving to avoid flagging and get the ...
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Why is it illegal to castle with both hands?
I was watching the match between Ian Nepomniachtchi vs Hikaru Nakamura and Nakamura used both hands to castle.
Why is it illegal to castle using both hands? What's wrong with that?
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USCF: Should the arbiter correct illegal moves without a player claim?
Should an USCF arbiter correct illegal moves without a player claim?
Here is the USCF link: USCF rules of chess
Here is the FIDE link: FIDE rules of chess
USCF and FIDE rules are NOT 100% equal.
What ...
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Why isn't legal move filtering done at search time?
Most engines have some method of filtering out pseudo-legal moves from the actual legal ones. However, is there any reason not to keep them? With bit-boards, you can quickly filter out the ones that ...
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"Highest" level of illegal move
For example, was a GM ever caught on an illegal move? Of course, only standard time control (everybody still remembers Carlsen-Inarkiev, but that was a blitz game) and after FIDE codification of chess ...
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Is this move illegal?
I'm currently writing my own chess game with my own AI and have a Question about a move:
Here, Purple moved his Pawn from F2 -> F3, which allowes the Green Queen on H4 to capture the King, and I ...
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How do you know when a FEN position is legal?
I am making a research on validating FEN positions, at first it is obvious the basics things to look for, such as checking if there are only two kings and making sure the rows or columns add up and ...
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Is blocking a check with a check an illegal move?
Say my opponent puts me in check. If I move my queen to block the check and it also puts my opponent in check, is that legal?
CommunityBot
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Can a player win if their opponent has made 2 illegal moves, but a helpmate isn't possible?
Suppose that in a KQ vs. K endgame (or in an endgame where Black can't possibly mate the other side), White makes two illegal moves. Can Black claim a win?
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5D Chess - Why is white king not in check in this position?
Why cannot black rook on c5 in the bottom timeline capture the king on c5 in the top timeline? Why is the king not in check?
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What are the official rules if your opponent makes an illegal move?
I heard that they lose some time or that they lose the game. I'm not sure what happens.
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Series of illegal moves in check
This question falls under FIDE rules (USCF answers/comments welcome).
If I make an illegal move leaving myself and my opponent in check, hit the clock and my opponent misses it and then continues play ...
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The illegal moves in Carlsen-Inarkiev
In the first round of the World Blitz Championship in Riyadh. Magnus Carlsen played Ernesto Inarkiev and the game ended strangely.
[FEN ""]
[StartPly "53"]
[Event "World Blitz ...
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Illegal promotion in FIDE blitz game? [duplicate]
In a FIDE rated blitz (3+2) tournament (following the official FIDE rules), the following position occurred:
[FEN "8/1k5P/q7/8/8/8/6K1/6Q1 w - - 0 1"]
White played 1.h8Q. But since both queens were ...
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Hitting the clock without moving
In an official blitz game, what happens if a player hits a chess clock without making a move? I believe that making an illegal move in a blitz game is an automatic loss. But does this count as an ...
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Capturing the king in a blitz game
In a blitz game, when my king is checked, I make an illegal move that checkmated the opponent and pressed the clock. Then my opponent captured my king and claimed victory. Capturing the king is not a ...
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Is this an illegal chess move?
Can the White king move to g2 to checkmate?
8/8/8/8/4Q3/7k/5K2/8 w - - 0 1
1. Kg2
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Can I hover my finger over a chess piece without touching it in a major chess tournament?
Noob question: I am aware of the no-touch rule, but can I point or hover my finger over a chess piece in a major tournament? To clarify, let's say it's my turn and I am thinking about which piece to ...
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How to create PGN notation with wrong moves in it?
I was as chess trainer with some young guys on a tournament, and wrote down some of their games. In nearly every game, there were wrong moves in it: king is in check, but does not move or react; ...
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Illegal Move Missed-Too Late?
This question is about standard games under USCF rules (if FIDE is different, I'd like to know). Say that one side makes an illegal move-specifically, castling through check. Neither player notices. ...
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Outcome of a game in case of an illegal checkmate
Suppose that, in an amateur rapid play tournament (where supervision is inappropriate), the following position appears:
[fen "5K2/8/1q6/1N1k4/8/8/8/2R1R3 w - - 1 1"]
1. Re5+? Qc5+? {...
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Pawn promotion to queen of the other color
A Black pawn reached the end of board and Black himself picked it up and placed a White queen on the board. He removed his hand from the piece.
I am not concerned with 'the spirit of the game' but ...
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Is taking the opponent's king an illegal move?
In competition blitz games, making an illegal move and then pressing the clock forfeits the game if the opponent claims the illegal move as long as they do not make a new move, as a new move would ...
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What happens if a player makes an illegal move and nobody notices?
What happens if a player makes an illegal move (i.e. a realistic case could be, he castles after he already moved the King), but none of the player notices, and the game goes on and on for a lot of ...
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Check and checkmate on following moves
I was playing chess with a buddy, and I put him in check. On the following move, without moving his king out of check, he moved a rook to put me in checkmate.
My questions are as follows:
Can he ...
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Are there any legal positions known to be impossible to come to in a normal game? [duplicate]
There are some fairly obvious ways to set up a chess board that cannot possibly happen: both kings simultaneously in check would be one.
There are some positions that seem impossible in a normal ...
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Touch move and capture sequence
When considering the touch move rule, I am still unclear about the legal sequence for a capture. Example, white intends to capture a took on a8 with rook on a1 (open file). Does white have to touch ...
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How is this move illegal?
I'm black and it's my turn. I'm playing in the Arena chess player against Stockfish.
This is my current board:
[fen ""]
[startply "31"]
1. e4 d5 2. exd5 e6 3. dxe6 fxe6 4. Nf3 Nf6 5. Bc4 c6 6. O-O ...
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I made an illegal move. What happens?
Especially in blitz or bullet games, it is possible that a player makes an illegal move, for example castles through check.
If the opponent does notice the illegal move, then as far as I know the ...
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Can a king be checked with another king when checking square is protected by the side which gives the check? [duplicate]
Can a white King move next to a black King to check it, if there is a white pawn protecting the white King, preventing the black King from taking the white King?
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Can I move a piece protecting the king if it keeps protecting on its new location?
Situation: there's a piece between the king and an opponent’s piece. If this piece were not there, it would be a check.
If I were to try and move the protecting piece somewhere and leave the king ...
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Illegal move or checkmate? [duplicate]
I was playing chess with an opponent. He had his queen in front of his king. I attacked the queen and he moved her, exposing his king directly to my rook. It was my turn to move, not his. We couldn't ...
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What happens if I realize that I made an illegal move? [closed]
Say I somehow make an illegal move, what happens? If I realize, can I then take it back, and make it legal? If so, how?
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FIDE rules when opponent accidentally promotes to your Queen
This happened to someone else recently in a time scramble during an OTB game. His opponent promoted a pawn and placed a Queen of the wrong color on the board. He was corrected by the player and the ...
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Why is it illegal to move into check?
In chess, it is against the rules to move into check, or to not move out of check. But why? Obviously, if you went against this rule, you'd immediately lose. But it seems strange to make it illegal to ...
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Is it possible to play 1 minute bullet with no increment over the board?
Playing 1 minute bullet games with no increment on the Internet is hard enough, but what about over the board, in real life with an actual wooden board?
Would it be possible, or would 90% of the ...
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We found out that we made an illegal move later on in the game [duplicate]
I am playing with my friend. I didn't notice that my king was in check, so I made an illegal move. We noticed this after several more moves.
What should happen next? Do we restart the game or ...
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How to detect invalid pawn structures (not based on opponent material) for FEN valdation?
I'm going to further expand a FEN validation function I have been working on for some time to include illegal pawn formations such that:
... for example white pawns could
never be on a2, a3, and ...
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How can I use pgn-extract to remove a game from a pgn file when there is an illegal move?
How can I use pgn-extract to remove a game from a pgn file when there is an illegal move?
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Can a piece pinned to my king put the opponent's king in check?
I was playing a game with a friend online. A situation came up where he put me in check with his bishop, and I moved my rook to block it. His king was on the g file and my rook was on g2. The website ...
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Why is castling through and out of check prohibited?
Why is castling disallowed when the king is in check or when the square the rook will be placed on is under attack?
What is the rationale behind this ruling?
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How to notify check when a player leaves himself in check
I'm learning to play chess.
Twice we had a situation where the white player moved a piece that was blocking the black Queen from checking the white King. There was no move available to announce "...
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