Move Repetition Decisions (Part 1)
A threefold repetition of the position implies an interesting decision for one or both players - whether or not to deviate. The following is a position from a game I (with the Black pieces) played in 2015.
White (2048)- Black (2198)
Before continuing, I suggest you pause and think about the position for a bit. Black is an exchange for a pawn down, and there is a perpetual available by checking back and forth on d3 and h3 (27...Qd3+ 28 Qe2 Qh3+ etc.). You have about ten minutes remaining on your clock. Make a decision.
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For context, I had earlier played a sacrifice I was quite happy with. In fact, I expected it to lead to a quick win. However, my opponent defended well, and the above position arose. Black is an exchange for a pawn down, without any immediate mate just yet. I should mention that in general I'm not one to sacrifice material, so I was naturally a bit sceptical of my position. Without much clock time left to make a decision, I decided I didn't have enough resources to checkmate the White King, ended up taking the perpetual.
I didn't think much of this until I eventually ran the game through a computer, which gave Black a serious advantage in the final position (nearly -1). This was surprising to me at first, but it makes a lot of sense. Once you realize that Black does not, in fact, need to give mate, and he has a huge positional advantage for a relatively small amount of material, it becomes obvious that Black should play on.
| In White's Favour | In Black's Favour |
| Material Quantity (one extra "point" of material) | Far superior king safety |
| Material Quality (excellent B/d4; ...Nd7-c5; Queen attacking as opposed to defending, etc.) | |
| Pawn structure (b2 is hanging, and f4 can potentially drop off) | |
Given all this, objectively the correct decision was to continue play with 27...Qh5! Below I've put an analysis file detailing some possibilities of how the game could go.
I suppose the moral of the story is that sometimes you just have to trust that your positions various plusses will end up compensating for the material in the (relatively) long-term, even if there's no immediate mate. I would hope in the intermittent year and a half since this game was played, I've learned my lesson and would play more ambitiously next time a similar situation arose in one of my games.
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Appendix A: Solely for my amusement, I ran an engine match from the position after 29...Qh5. Here are the results:
(Houdini A had White in all six games; Houdini B had Black.)
