simultaneous stalemate and checkmate

In chess, a stalemate arises when there is no possible legal move a player can make.
Checkmate arises when a player is in check and there is no possible move he can make on the next turn that would allow him to not be in check. It is not explicit, but the obvious concept here is that if the player did not get out of check his king would be captured on the next move.

I got to thinking, what if a situation arises where there is no possible move a player can make (even if moving into check was allowed) but the player is in check.

Obviously this would require the player’s king to be completely surrounded by his own pieces, and the opponent’s knight instigating the check, because otherwise the king could still theoretically make a move, even if it was into check.

So the question is: Would this still be checkmate? Should it be considered a checkmate?

It is true the knight would presumably capture the king on the next move, but before that could happen one of the players is not capable of making any move.

Even if this is considered a checkmate by definition, I am not sure it should be considered a true checkmate. In the game of chess, each player has to make one (and only one) move. When a player becomes incapable of doing this the game is immediately over.

The only reason moving into check is not allowed is because the king would be captured on the next move. So, the way I see it, the hypothetical move into check is not forbidden in the same sense that, say, moving the king 2 spaces across the board would be against the rules.

If the rules of chess were slightly changed, allowing the king to move into check, the overall game would basically not be any different. Sure, you’re welcome to move into check, but if you do you are pretty much guaranteed to automatically lose. This is what I’m talking about. So supposing we were playing by those rules, if I manage to get into a position where I am still incapable of making any move on my turn, shouldn’t that be considered a stalemate??

If we do not allow the hypothetical situation I described to be considered a stalemate, then the rule about not being allowed to move into check fails to make intuitive sense. The king should be allowed—if only hypothetically—to move into check, and that should count as a hypothetical possible move—thus precluding the condition of a stalemate. In a regular checkmate, we know where the game would inevitably be headed: the king will be captured.

But if the condition of a stalemate arises before the king can be captured, then there is no winner.

I am just thinking maybe the rules of chess should be modified to more carefully define the definitions of checkmate and stalemate.

I think you’re misreading the definition of checkmate. If the king is in check, and there’s no possible move that can get the king out of check, that is checkmate. It doesn’t matter if the king is in check from a knight, and moves to a square where it is in check from a bishop, or if it is in check from a bishop, which is then captured but leaves the king in check from a rook.

Note that the rule against the king moving into check is so absolute that a king is not allowed to castle* through* check (nor to escape from check,) even though castling is considered one continuous move and would end with the king not being in check.

As a chess player I am finding really hard to follow your post.

If the situation you first describe arises then it is clearly checkmate. You are in check and you cannot get out of check (by one of either by capturing the piece giving check, moving a piece in-between so as to block the check or moving the king out of check) then it is checkmate. No ifs or buts - simple rules of chess.

Having your king surrounded by pieces but being checkmated by a knight is called smothered mate, and is a common tactic classically following a queen sacrifice where the queen moves diagonally next to the opposing king given check such that the only move to prevent it is to capture the queen (most often by a rook) and leaving it open for a knight to deliver checkmate as the rook now occupies the kings only previous escape square.

In your second example, the game would be clearly different. If the piece giving check was itself pinned (against his own King) it could not legally move to “capture” the king that was either left in check or moved into check. Several other rules would have to be amended.

The rules of chess are simple. There can be no simultaneous stalemate and checkmate. They are almost identical concepts other than with stalemate the king is not actually in check!

Go through the first diagramme for the queen sac knight mate theme.

I think I kind understand your point : First, you make a distinction between ‘regular’ movement rules that forbid certain moves because of the rule of how pieces move and capture (for pawns) or the rule forbidding two pieces from occupying the same square without a capture, and the ‘no-check’ movement rule that forbids putting the king into check. And then you make a distinction between the situation where a player has no legal moves solely because of ‘regular’ movement rules and the situation where a player has no legal moves because of at least one instance of the ‘no check’ rule. (I think we agree that in both cases, if the king is not in check, this is stalemate)
You seem to say that if the king is in check, in the second situation this is clearly checkmate, but in the first, the stalemate should somehow come into play keeping this from becoming checkmate.

But understanding is not the same thing as agreeing. First of all, legally, the rules of chess are clear that even the first situation is checkmate; the fact that it would otherwise be stalemate is irrelevant. Theoretically, I’m unconvinced that the distinction you’re making is fundamental or relevant. And practically, I can’t imagine how such a situation would come about without both sides intentionally making it happen [easiest that I have come up with: White King at a8, bishop b8, pawns a7,b7, c7. Black anything at c8, and knight at b6. Anyone got a better one?].

So, points for creative distinctions, but I don’t agree that this is a real issue.

I just think it should not be considered check if the game will be over before the king can be captured.

NOPE, NOPE, NOPE. I got that wrong.

Current easiest solution I have involves five pawns on two files (with a rook); needing, I think, eight pawn captures to get them there. I’m not even absolutely sure it’s possible with both sides colluding.

Zach29 - have you read my post and looked at the link?

Would you prefer a game where a queen sac followed by smothered mate was a draw? It would be impossible under your version because the king in check would claim a draw by stalemate because he did not have an escape square before the king could be “captured”.

This would just be because the attacker set up a forced series of moves that deliberately did not allow an escape square for the king! If he did it would not be mate. Thus smothered mate could never occur. All those beautiful forced continuations would have never seen the light of day.

I really don’t understand what your issue is with stalemate versus checkmate. I don’t think you know much about chess is the only conclusion I can draw.

All chess games end without any kings being captured.

Look, what is the definition of “check” if we try to precisely define it?
It is when the players king would be captured on the next move.

So if we try to apply pure logic to analyze this situation, the question is can any further moves legally be made after the game has ended? Well, in the case of a stalemate, we know the answer is no, even if a checkmate is only one move away.

When we really try to analyze the situation we realize circular logic is involved here; if it will result in a stalemate, it cannot be check because the next move, and by extension the next move after that capturing the king, will not be allowed. Conversely, if it is not the end of the game, then capturing the king on the next move will be allowed and it is indeed check—in fact checkmate. But for the game to reach its hypothetical logical conclusion where the king is captured, one player will have had to go a turn without moving any pieces—another seeming contradiction.

In that case, if we played the game out to its logical conclusion, one of the kings would be captured before the other. So the player who moved his piece to try checkmate the other player while exposing his king to check would end up losing. So there is no inconsistency here.


Look mate (no pun intended), if you don’t know what the definition of “check” is (clue: it is not what you state) then I cannot help you.

From FIDEs website:

The king is said to be ‘in check’ if it is attacked by one or more of the opponent’s pieces, even if such pieces are constrained from moving to the square occupied by the king because they would then leave or place their own king in check. No piece can be moved that will either expose the king of the same colour to check or leave that king in check. *

Nothing about your hypothetical “what happens next move”.

Go to and cut and paste the following FEN into the analysis board:

8/8/5Npp/5prk/5Ppr/3K2Pp/7P/8 w - - 0 1

the king is against the side of the board, there is a rook below him and to another to the side, and they are surrounded by 5 pawns so they can’t move, with 3 of the opponent’s pawns blocking the front.

The player cannot legally make any move, but he is in a seeming checkmate by his opponent’s knight.

one more important point, make sure when you highlight that FEN code to copy it you do not have the blank space after the last number highlighted, it will mess it up.
8/8/5Npp/5prk/5Ppr/3K2Pp/7P/8 w - - 0 1

might display better here:

click on “set FEN”

What exactly does “attacked by” mean? I know this is seems obviously intuitive, but if we had to precisely define it to program into a computer program?

And how do we logically define “expose” ?
Doesn’t that mean “could be legally taken in the opponent’s next move” ?
Does this still fit the precise logical definition if the state of a stalemate exists before the opponent’s next turn?

Look, if we rigidly hold to the exact rules, and logically analyze the meaning of the terms in the rules, applying strict logic, there are some unexpected implications.

It’s really quite simple - in a situation such as you describe, where a player makes a move such that he has no legal move on his next turn; if his opponent manages to put him in check on his move, and the first player still has no legal moves that get him out of check, it is checkmate. If the opponent fails to either put him in check or break the stalemate, it is stalemate.

“A piece is said to attack an opponent’s piece if the piece could make a capture on that square according to Articles 3.2 to 3.8.”

If you want to find a loophole in the rules, at least read the rules.

Look at notquitekarpov’s pdf link, it gives examples which illustrate the theme and how to get there in a natural fashion.

It doesn’t because there is no legal move in chess that results in a king being captured. Ever.

You mention defining things for a chess computer. Thinking about how one would do that to resolve stalemate/checkmate simplifies your issue greatly. All the logic you would need is:

Can I make any legal moves?
If no:
–Am I in check?
–If no:
–If yes:

Nothing else matters.

If I’m understanding Zach29 correctly, those smothered mates don’t fit what he’s describing. He’s talking about cases where, if you ignore the check, the position is stalemate. So those smothered mates don’t apply, since if he wasn’t in check the player would be able to move some other piece.

Having said that, the rules seem clear on this to me. It’s true that the motivation for the checkmate rule is the idea that the king can’t avoid being captured, but the actual rules of the game don’t involve capturing the king. The game is just over when a checkmate position arises.

But it just does not seem intuitive. I can understand why, under normal circumstances, it would be forbidden to move into check, because then your king would be captured and you would lose, if the game was allowed to play out the next 2 moves after the checkmate.

But that is not necessarily the case when one of the players would be unable to move.

And how do we define exactly what a “check” really is? Should it just be taken to mean that you should be on guard, and that there is no point to moving into check because you would just lose your king? In that case, moving into check is not forbidden in the same way that other moves are forbidden. I think that is where the concept of “check” and “checkmate” originated from. It just goes without saying that your king would be taken, so what is the point of letting you take it?

However, as kunilou pointed out, the one major exception is castling when the king would merely pass through check. Still, this little rule just does not seem very consistent with the rest of the game to me.

“Checkmate” should not be the end of the game when a stalemate is inevitable before the king could be captured, that is what I am thinking. Should it really be considered a checkmate when the enemy king can escape capture through a stalemate, and thus no more moves being allowed on the board? When one of the players becomes unable to move any pieces, even unable to move any pieces that would expose him to check, that is a very significant thing.

Although in some ways, the definition of a stalemate is different, because in that case you could theoretically be able to move a piece, but doing so would expose your king to check.

What is so important about being exposed to check? Have we focused so much on that single aspect that we have lost sight of the original meaning of chess? namely, to be able to take the enemy’s king?