Monday, October 22, 2007

CT-Art 735

I was going to write a narrative on CT-Art 735 and decided to double check it on Fritz. It turns out the CT-Art solution has mistakes in multiple places.
CT-Art 735:

White to Move

The pawn on f7 is weak (only defended by king) and is the only defender of e6. In this kind of position, 1. Nxf7 Kxf7 2. Qxe6 immediately comes to mind as so many squares around the king can be controlled. 2. ... Kf8 is mated immediately by Bh6 so 2. ... Kg7 is forced. We can stay with forcing moves by 3. Bh6 Kh8 and now simply pry open the h-file with 4. Bxg6 where black loses quickly if 4. ... hxg6 5. Bf8+ Nh7 6. Rxh7+ Kxh7 7. Qf7+ Kh8 8. Qg7# (5. ... Nh5+ 6. Rxh5+ gxh5 7. Qh6+ Kg8 8. Qg7#). Other 4th moves for black give back excess material, e.g. 4. ... Rg8 5. Bf7.

The above is not the CT-Art solution. CT-Art starts off with 1. Nxf7 Kxf7 but then CT-Art gives 2. Rxh7. This is a good invading move, rooks are typically very well placed on the 7th rank:
Black to Move

The rook is immune from the knight, Nxh7 Qxe6 Kg7 Qxg6+ and mate follows with Bh6 or Qxh7. So black continues with 2. ... Kf8. Here CT-Art gives no credit for the very strong 3. Bxg6 instead favoring 3. Rh6 Bf8 (other moves may be better) 4. Rxg6 and then a serious error from the defense 4. ... Bg7? (Kh8 is more complex and doesn't lose nearly so quickly) which allows 5. Bh6 Nf4 6. Rxg7+ Qxg7 7. Bxf4 where white has three pawns for the exchange.

The CT-Art solution, while winning, is very complex compared to the first solution I gave. Even then, the solution given is helped along by inferior moves from the defense. A proper defense would have made this solution extremely difficult in practice.

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