Knowing and Doing

My opponent's draw offer leads me to believe that he understood that a queen vs. a c-pawn one square from promotion is a draw. Nonetheless, I demanded proof and the opportunity to present it was missed. Alas, my own errors allowed the draw to remain after my opponent's first error, and the queen vs. pawn occurred only because I exchanged rooks when they should have remained on the board.

My individual students saw this endgame last week and then most of them solved some exercises from Georges Renaud and Victor Kahn, The Art of the Checkmate (1953). My afterschool club solved worksheets with checkmate in one. This week, they will see mates in two from some of the same games.

Black to move

56...Rxf6??

Simple counting shows that the next diagram will be reached. I should have played 56...Rc4.

57.Kxf6= Kf4 58.Ke7 g3 59.Kxd7 g2 60.c6 g1Q 61.c7 Qa7

White to move

62.Kd8??

Now, we have reached a position that I know from endgame books. 62.Kc6 was the only move to hold the draw.

62...Qb6??

I know, but did not do. After 62...Ke5-+ 63.c8Q Kd6, White is in zugzwang with a worthless king. In fact, Black has a mate in three.

63.Kd7= Qb5+ 64.Kd8 Qd5+ 65.Kc8 Ke5 66.Kb8 Qb5+ 67.Ka7 Qc6 67.Ka7 Qc6 68.Kb8 Qb6+

White to move

69.Kc8??

69.Ka8=. Knowing this stalemate resource is essential to understanding why a c- or f-pawn against the queen is a draw when the pawn is one square from promotion.

69...Kd6-+

White resigned.