Saturday, January 07, 2006


Checkmate Calculation Conundrum

From: Tasc Chess Tutor v2.01, Copyright 1995-1999 Tasc B.V. Holland
Step 5, section 9c, #5
White to Move

This is from a "Test" section, so I had no hint that it was a mate problem. I am down to 4 minutes per problem, though I didn't even use all my time before I started guessing (bad!). Perhaps I was a little tired, but that's not much of an excuse. After not seeing any way to stop both pawns, I just started making lazy mate threats which FINALLY yielded the quiet answer of Rg56. Tricky, huh?

Qxh7 just posted about this, namely how is it that it's difficult to see mate in 2 when you can see easy mates in 3, 4, or even more. In spite of individual differences, I think players experience a similar phenomenon early in there career. To share my take on the whole issue, I have created some relatively simple forced mate examples, all White to move and all with a weak wrong move(s) possible.

  • Outnumbering: when cautious middlegame mentality gets in the way. If I ever get good enough to write a tactics book, outnumbering would be the largest chapter. Here are two positions with this theme that seem essentially equivalent to me, the only difference is the second one is difficult for more people to see right away.

    Same answer for both positions
    Weak move: Rd8+
    Answer: Rxh3+ gxh3 Rxh3#

  • Option Limiting: failing to see a quiet move, prophylaxis, or zugzwang. The second example is a test of finding the absolute best moves for both sides.

    Top postion
    Weak move: Rb8+
    Answer: Ra7 any Rb8#

    Bottom position
    Taking the Queen is obvious, so after Bxc7
    Weak move: ...Nxc7
    Answer: ...Nd6
    Now after Bxc7 Nd6 we get
    Weak move: Bxd6?? or Nf7? or Kg3?
    Answer: Several moves will work-Kh1, a6, Bb8, etc.

  • Uncommon Final Pattern. The TCT at the top certainly seems uncommon to me.
  • Uncommon Tactic: destruction, clearance sacrifice, unusual looking absolute pins, multiple Tactics.

    Weak move: just about anything other than the answer.
    Answer: Rxc6!. Now ...Bxa4 is the only way to avoid b5#, but leads to Qxa4#


I'm not all that experienced like a trainer, but I can speak to what I do. After I follow the forcing checks and moves and not finding the answer, I attempt a few things which have helped me to shift towards the solution in the past:

  • Review it. I still make mistakes calculated, so I can tend to go over it again to see if I have messed anything up.
  • Break visual attention/move around (like for 30+ seconds). Actually this one has been more helpful than trying to think tactically.
  • Look for any possible absolute pin, no matter how unlikely it looks.
  • Break the rules. Calculate if you could move on top of or even through your own pieces, or make two moves to achieve mate. This is known as "null move" thinking, and is a powerful optimization in computer chess engines.
  • Finally review the "Fundamental Checkmates" and attempt to apply it to the position.


TCT Results

Circle 1Circle 2Circle 3Circle 4
Step 197%99%99%100%r
Step 293%96%95%97%
Step 393%97%97%96%
Step 480%86%90%92%
Step 574%



I understand what you mean. I had trouble with most of these in the past. But now these costed me little time (<30 seconds).

In comparison to other combinations I'm very strong in finding checkmate.
A simple double attack will always cost me 30+ seconds while a simple mate in 3 is found "immediate" most of the time. Especially Polgars book was good to learn how to checkmate.

Actually this is the reason why I don't resign early when behind in a game. Because I have a rather unusual background with tactics, I never know which combinations are hard to find for my opponent.
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Bottom position
Taking the Queen is obvious, so after Bxc7
Weak move: ...Nxc7
Answer: ...Nd6

I think in this position one doesn't even need to take the queen one should go directly to Nd6 checkmate.Although checkmate is unavoidable even if you take the queen first.

I love these positions where one can stack the knights in a column or a row. They cover so many squares.
>I think in this position one doesn't even need to take the queen one should go directly to Nd6 checkmate.

Takchess - I'm not sure I follow you, but there is an absolute pin that immobilizes White's e5 Knight so no mate in one. Was that it?

The intended idea was twofold- that White needs to unpin and avoid a stalemate.
That is from the "Test" area, therefore i Cheap wow golddidn't have touch that this was a spouse trouble. My business is into Some moments each difficulty, although I didnt make use of my period just before I started guessing (negative!). Maybe I used to be somewhat worn out, that is not much of your justification. Immediately after certainly not discovering however to prevent both equally pawns, I merely started out doing sluggish lover provocations which Lastly exhibited the Buy rs goldparticular tranquil answer connected with Rg56. Difficult, so ??
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