|Chessmaletaja: With his move <12. h4!> White threatened 13. h5. Whether Black can block it or avoid opening the h-file? |
12...h6? 13. h5 Δ 13...g5? 14. ♕d3 +-
12...h5 13. e6! Δ 13...♗xe6 14. ♗xg6! ±
My chess engine Komodo says that Black's best move is 12...♘c7 ±.
But Black still tried to hinder White's h-pawn and played
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Here, 13. ♕e3 ± is a sufficiently good move. But White played
<13. h5! +->
To make such a move, White had to make some calculations, in the position shown above.
13...gxh5?? 14. ♕d3 +-
It is also easy to calculate something like that:
13...♗xh5? 14. ♖xh5! gxh5 15. ♗xh7+! ♔xh7 16. ♘g5+
16...♔g8? 17. ♕xh5 ♖e8 18. ♕xf7+ ♔h8
White can see in his calculations that he has at least the eternal check. But maybe something better, it can be checked if that position arrives on the board.
Maybe the grossmaster is able to see that
19. ♕g6! ♔g8 20. ♘e6 checkmates.
But what after
Perhaps even a grossmaster does not see a forced win in that position. Perhaps one simply evaluates the position and one's winning chances. Having some memories about similar positions. I do not know.
My analysis shows the following possible continuation:
17. ♘df3 f5
Black's only hope. Now, White has the life insurance 18. ♘e6, but better is
18. ♘h4+ ♔h6 19. ♘f7+ ♔h7 20. ♕xh5+ ♔g8 21. ♘g5! +-
Again, White has at least the eternal check, in addition, probably White can win the queen after 21...♖e8 22. ♕h7+ ♔f8 23. ♘e6+.
So White does not actually need to calculate everything till the end of the variation, which should be:
Δ 21...♖e8 22. ♕h7+ ♔f8 23. ♘g6 #
It is 10 moves starting from 23. h5! and finishing with 23. ♘g6 #.