Wednesday, October 24, 2007

Counting again

In one of the problems in unit 10 module 3 of PCT I encountered this position:

White plays 1. Nxd4 and wins a pawn. That baffled me. I would have sworn that Nxd4 would lose a piece. Counting is obviously a weak spot of mine. Hence I intend to take some time off to formulate a narrative for this position. These are the kind of positions that GM Henrik Danielsen solves à tempo in blitz games.

1. Part counting part the Queen would be first (or the pinned knight) to take. If the knight takes then the counting is complicated by bishop takes rook. If the queen takes first then the value of the pieces exchanged favors White...

2. Very complicated because of the two scenes, one in the d-file and one with the hanging Bishop g5. Without this Bishop, 1.Nxd4 certainly would win material. So we have to look at the reply 1.-hxg4 and if we gain back the piece everything is okay. Do we? 2.Nxc6 looks fine because the Knight can hop away from there with check, thus we have the piece back. The Queen cannot retreat because this would lose the Exchange at d8. Therefore 2.-Qxd2 seems to be best, giving the Queen for two Rooks. 3.Rxd2 Rxd2 and now the square e7 is free for the Knight check, and in the next move, White saves his Queen. I haven't checked this with the computer, but may this be the main variation?

3. A fantastic problem! This is a lunch problem for tomorrow :)

4. (I thought I already posted this comment but blogger must have eaten it).

D'oh. In my first comment and first look at this position I totally overlooked that the Bishop at g5 was hanging. I only saw the action at d4.

Thanks christian, now I get it.

5. There are other red herrings in this problem as well. For example, 1. Bxf6 Qxf6 2. Bxc6 bxc6 and now it appears that 3. Nxd4 just wins the pawn by counting, but black has 3. ... Bxc2.

6. I haven't studied the problem -- this is just from a quick glance -- but doesn't the knight that takes the pawn on d4 protect the pawn on c2? And if black takes the knight on d4, doesn't he lose the exchange?