On the board: black king vs. white king with knight and rook. Could checkmate be done without the white...












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Just something I randomly came up with. Sorry if it is a duplicate.










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  • Close voters: IMHO (which as always could be wrong) this question is not too broad. It could benefit from a picture, perhaps, but it sounds like a standard endgame-style question. (i.e. "Can King and Rook draw vs King and Queen?"). The location of the pieces is assumed to not have any immediate tactics.

    – Brandon_J
    21 mins ago
















1















Just something I randomly came up with. Sorry if it is a duplicate.










share|improve this question

























  • Close voters: IMHO (which as always could be wrong) this question is not too broad. It could benefit from a picture, perhaps, but it sounds like a standard endgame-style question. (i.e. "Can King and Rook draw vs King and Queen?"). The location of the pieces is assumed to not have any immediate tactics.

    – Brandon_J
    21 mins ago














1












1








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Just something I randomly came up with. Sorry if it is a duplicate.










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Just something I randomly came up with. Sorry if it is a duplicate.







theory checkmate






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edited 6 hours ago









Brian Towers

15.5k32967




15.5k32967










asked 7 hours ago









Rewan DemontayRewan Demontay

309212




309212













  • Close voters: IMHO (which as always could be wrong) this question is not too broad. It could benefit from a picture, perhaps, but it sounds like a standard endgame-style question. (i.e. "Can King and Rook draw vs King and Queen?"). The location of the pieces is assumed to not have any immediate tactics.

    – Brandon_J
    21 mins ago



















  • Close voters: IMHO (which as always could be wrong) this question is not too broad. It could benefit from a picture, perhaps, but it sounds like a standard endgame-style question. (i.e. "Can King and Rook draw vs King and Queen?"). The location of the pieces is assumed to not have any immediate tactics.

    – Brandon_J
    21 mins ago

















Close voters: IMHO (which as always could be wrong) this question is not too broad. It could benefit from a picture, perhaps, but it sounds like a standard endgame-style question. (i.e. "Can King and Rook draw vs King and Queen?"). The location of the pieces is assumed to not have any immediate tactics.

– Brandon_J
21 mins ago





Close voters: IMHO (which as always could be wrong) this question is not too broad. It could benefit from a picture, perhaps, but it sounds like a standard endgame-style question. (i.e. "Can King and Rook draw vs King and Queen?"). The location of the pieces is assumed to not have any immediate tactics.

– Brandon_J
21 mins ago










1 Answer
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I don't think it is possible to forcibly mate the king with rook and knight only.





Proof: The only mating position is with the black king in a corner, the rook giving check from an adjecent square and the knight protecting the rook and covering the escape square.



For simplicity let's say Ka1, Rb1, Nc3. There are 7 other equivalent positions to this one.



If you retro-analyze the position the last move must have been with the rook along the b file from somewhere between b3 and b8. For the folowing analysis it does not matter from where it came.



Then what was black's last move? It certainly was a king move moving from a2, b2 or b1 to the corner (a1). However, since black was not forced to move the king to the corner but could have moved to a3 or c1 (or to b3 if the rook was standing there), the mate cannot be forced.






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  • 2





    For completeness, I guess you have to analyze the possibility that the rook came from b3 preventing Ka3. Of course, then Kxb3 would have been possible.

    – D M
    7 hours ago











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1 Answer
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active

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1 Answer
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active

oldest

votes









active

oldest

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active

oldest

votes









2














I don't think it is possible to forcibly mate the king with rook and knight only.





Proof: The only mating position is with the black king in a corner, the rook giving check from an adjecent square and the knight protecting the rook and covering the escape square.



For simplicity let's say Ka1, Rb1, Nc3. There are 7 other equivalent positions to this one.



If you retro-analyze the position the last move must have been with the rook along the b file from somewhere between b3 and b8. For the folowing analysis it does not matter from where it came.



Then what was black's last move? It certainly was a king move moving from a2, b2 or b1 to the corner (a1). However, since black was not forced to move the king to the corner but could have moved to a3 or c1 (or to b3 if the rook was standing there), the mate cannot be forced.






share|improve this answer





















  • 2





    For completeness, I guess you have to analyze the possibility that the rook came from b3 preventing Ka3. Of course, then Kxb3 would have been possible.

    – D M
    7 hours ago
















2














I don't think it is possible to forcibly mate the king with rook and knight only.





Proof: The only mating position is with the black king in a corner, the rook giving check from an adjecent square and the knight protecting the rook and covering the escape square.



For simplicity let's say Ka1, Rb1, Nc3. There are 7 other equivalent positions to this one.



If you retro-analyze the position the last move must have been with the rook along the b file from somewhere between b3 and b8. For the folowing analysis it does not matter from where it came.



Then what was black's last move? It certainly was a king move moving from a2, b2 or b1 to the corner (a1). However, since black was not forced to move the king to the corner but could have moved to a3 or c1 (or to b3 if the rook was standing there), the mate cannot be forced.






share|improve this answer





















  • 2





    For completeness, I guess you have to analyze the possibility that the rook came from b3 preventing Ka3. Of course, then Kxb3 would have been possible.

    – D M
    7 hours ago














2












2








2







I don't think it is possible to forcibly mate the king with rook and knight only.





Proof: The only mating position is with the black king in a corner, the rook giving check from an adjecent square and the knight protecting the rook and covering the escape square.



For simplicity let's say Ka1, Rb1, Nc3. There are 7 other equivalent positions to this one.



If you retro-analyze the position the last move must have been with the rook along the b file from somewhere between b3 and b8. For the folowing analysis it does not matter from where it came.



Then what was black's last move? It certainly was a king move moving from a2, b2 or b1 to the corner (a1). However, since black was not forced to move the king to the corner but could have moved to a3 or c1 (or to b3 if the rook was standing there), the mate cannot be forced.






share|improve this answer















I don't think it is possible to forcibly mate the king with rook and knight only.





Proof: The only mating position is with the black king in a corner, the rook giving check from an adjecent square and the knight protecting the rook and covering the escape square.



For simplicity let's say Ka1, Rb1, Nc3. There are 7 other equivalent positions to this one.



If you retro-analyze the position the last move must have been with the rook along the b file from somewhere between b3 and b8. For the folowing analysis it does not matter from where it came.



Then what was black's last move? It certainly was a king move moving from a2, b2 or b1 to the corner (a1). However, since black was not forced to move the king to the corner but could have moved to a3 or c1 (or to b3 if the rook was standing there), the mate cannot be forced.







share|improve this answer














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edited 6 hours ago

























answered 7 hours ago









user1583209user1583209

12.2k21554




12.2k21554








  • 2





    For completeness, I guess you have to analyze the possibility that the rook came from b3 preventing Ka3. Of course, then Kxb3 would have been possible.

    – D M
    7 hours ago














  • 2





    For completeness, I guess you have to analyze the possibility that the rook came from b3 preventing Ka3. Of course, then Kxb3 would have been possible.

    – D M
    7 hours ago








2




2





For completeness, I guess you have to analyze the possibility that the rook came from b3 preventing Ka3. Of course, then Kxb3 would have been possible.

– D M
7 hours ago





For completeness, I guess you have to analyze the possibility that the rook came from b3 preventing Ka3. Of course, then Kxb3 would have been possible.

– D M
7 hours ago


















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