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I just have a quick question. I was playing on chess.com and got into the following position:

[FEN "8/4n/6k1/8/K2/3N1/8/8 b - - 0 1"]

Now, I assumed that once we traded off the last pawns, the game would automatically draw as it usually does. However, since if didn't, I was wondering if it was possible to checkmate in this position. I know on some occasions it's possible to checkmate with really weird positions (e.g king and bishop vs pawn and king assuming the pawn doesn't move, or something similar to this), but I had always assumed that the position I was in was a draw.. Also, if a checkmate is possible, would it have to be as a result of a blunder or would it be able to be forced?

  • KNN - K is accounted a draw so why do we bother? – Joshua Apr 29 '17 at 20:10
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According to USCF rule 14E2, if your opponent has only a king and knight (and no forced mate) and you run out of time, the game is drawn. According to FIDE rules, the game is not drawn if there is any legal sequence of moves leading to mate. Chess.com appears to use something similar to the USCF rules for this situation; it says "... note that in cases where the opponent has insufficient material to mate (lone King, King + Knight, King + Bishop, King + 2 Knights) a draw will be automatically declared where there is a time-out." So even if the game doesn't immediately end and you've only got 5 seconds left, you don't have to panic.

Also, if a checkmate is possible, would it have to be as a result of a blunder or would it be able to be forced?

In the position you give as an example, even a single "blunder" isn't sufficient to lose. Your opponent can't even force your king to move more than one square from where it's sitting, let alone force it into the corner; and even if you did move it to the corner, there's no way to force your knight to go alongside it when it literally has the entire rest of the board to use. A checkmate would probably be the result only if someone was trying to lose, although it could perhaps also happen if there was an extremely ill-advised attempt at inducing a stalemate.

But it is possible in other positions that the knight vs knight situation happens in exactly the right spot for a forced mate in one (which is probably why chess.com does not simply declare a draw when you reach knight vs knight.) Here's an example where Black is forced to take the White queen with his knight, setting up a knight vs knight checkmate.

[White "NN"]
[Black "NN"]
[FEN "6qk/8/5nKN/8/2Q5/8/8/8 w - - 0 1"]
[SetUp "1"]
[CurrentPosition "6nk/5N2/6K1/8/8/8/8/8 b - - 1 2"]

1.Qxg8+ Nxg8 2.Nf7#  

Interestingly, there is no point where Black could abuse the time-out draw rule and intentionally let his clock expire for a draw; before he plays Nxg8, White has sufficient material. So stalling can't save him in this position.

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If a checkmate is possible, would it have to be as a result of a blunder or would it be able to be forced?

Mate is possible. This could be the final position:

[FEN "8/8/8/8/8/1K6/2N5/kn6 b - - 0 1"]

However this cannot be forced. According to the tablebases, the game is a draw with correct play.

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    And, here, "correct play" means, "Come on, dude. Don't park your king in the corner and then put your knight next to it. Anything else, literally anything is fine. Heck, even let the other guy take your knight for the insta-draw." – David Richerby Apr 29 '17 at 13:48
  • @DavidRicherby Interesting. Can you force a knight sacrifice? – JBentley Apr 29 '17 at 14:21
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    @JBentley No. Too long to demonstrate this in a comment, so I posted a new question and answered it. – David Richerby Apr 29 '17 at 15:40
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It is, of course, objectively a draw. But according to the FIDE rules, the game can be declared a draw (without agreement of both opponents) only if there's no sequence of moves that can lead to a mate. Here the sequence leading to mate exists, even thought it is really illogical. Here is just a random example:

4k3/8/7n/4K3/8/6N1/8/8 w - - 0 1

1. Kf6 Kf8 2. Kg6 Kg8 3. Ne4 Kh8 4. Nd6 Ng8 5. Nf7#

The problem is similar to king + 2 knights against king. Again, obejctively a draw, but after a blunder/s mate is possible.

Websites like chess.com use similar rules as FIDE does. So that was the reason, why your game wasn't declared a draw.

Therefore the only rule you can apply here to draw the game without agreement of your opponent is the "50-moves without capture or pawn move" rule.

  • Shouldn't you start out with the board looking like the question's board? – A Child of God Apr 29 '17 at 19:14
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    I was just giving an example on the sequence of moves leading to mate and wanted to keep it simple. I don't think it is important to include the original board, because the pattern of the mate is always the same, it will only take more moves. That being said: Haven't I convinced you yet, that the mate sequence is possible? – kmartin Apr 29 '17 at 19:25

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