One final thing

There is the oft repeated story of the father who leaves his entire fortune to his son, on the condition that "he never plays QxNP in the opening." In Euwe and Kramers "The Middle Game Book Two" there is a variant on this tale. In there version the fortune is left to the sons "only after they had made a correct Bishop sacrifice on KR7"

The game then given in the book is a brilliant win by Edgar Colle. But whether the sacrifice as played in this game is 'sound' has been the subject to some debate. Some old analysis thought it was unsound, if the Black King runs back to g8, although both Baburin, and Euwe/Kramer think that White still has a draw by perpetual. Interestingly they both thought that after 13. ... Kg8 14.Qh5 Ne5 15.Rxe5! Bxe5 16.Qxf7+ Kh8 17.Qh5+ Kg8 White only has a perpetual, but Stockfish quickly finds 18.b3! with a winning position. However 14. ... Qf6 (also given by both analysts) still holds for Black.

So if you are playing White, does sacrificing a piece for a draw qualify as 'correct', and do you qualify for your fathers inheritance?

Colle,Edgar - O'Hanlon,John [D05]

Nice Nice (9), 1930

1.d4 d5 2.Nf3 Nf6 3.e3 c5 4.c3 e6 5.Bd3 Bd6 6.Nbd2 Nbd7 7.0-0 0-0 8.Re1 Re8 9.e4 dxe4 10.Nxe4 Nxe4 11.Bxe4 cxd4 (D)

12.Bxh7+ Kxh7 13.Ng5+ Kg6 14.h4 Rh8 15.Rxe6+ Nf6 16.h5+ Kh6 17.Rxd6 Qa5 18.Nxf7+ Kh7 19.Ng5+ Kg8 20.Qb3+ 1-0