Chess Problems: The Self-block Put to Bed
3/27/2012 – This popular theme in problem chess – a piece on the defending side blocks a flight square of the king, thus enabling the attacker to mate – is also seen in normal games. In its pure form, or as a weakening with a delayed effect, examples on a par with composed problems are rare. Our problem expert David Friedgood asked our readers to look for OTB self-blocks. Here are some results.
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The Self-block Put to Bed
By David Friedgood
In the preceding article on the self-block theme, I tightened up the requirements for the best examples of games in which self-blocks played a part. [Definition of self-block: a unit on the defending side moves to a square to which the defending king could otherwise move, enabling the attacker to deliver checkmate]. Examples fulfilling these revised requirements proved very difficult to find.
Greek IM Ilias Kourkounakis sent me a selection of positions from his stock that he uses for training. He doubts that examples fitting my requirements are even out there to be found. Amongst his examples is the following one, which probably has a number of precursors of a similar nature. It is a neat illustration of what I call ‘impure’ self-blocks, that is, those which are produced not only for reasons of self-blocking, but have another motive as well:
Steven B Dowd, whose reviews appear quite often on this site and who is an accomplished problem composer as well, also sent me a few examples. After I strengthened the requirements though, he pointed out that it would be very difficult to search electronically for anticipatory self-blocks (a self-block which occurs some moves before the opponent takes advantage of it). This is a challenge in itself!
Michael McDowell, who is even better known in the problem world as a composer than as a former British champion solver, has an exceptional memory. He suggested a few pertinent games by historic personalities such as Joseph Henry Blackburne, of which the following one is perhaps the most interesting from a thematic point of view, with two self-blocks arising perfectly naturally:
An example of the kind of thing I have been looking for occurred in a game I played against my good friend Craig Pritchett, the Scottish IM and author, some years ago.
To put the self-block theme to bed for the time being (doubtless it will crop up many times in future articles), here are a couple of problems for solving, with self-blocks central to the composer’s idea. The solutions will be given next week.
Mate in two
You have to find White’s first (‘key’) move, which is the only one to force mate on the following move whatever Black tries to do about it. This move will threaten mate and all Black’s defences will create some weakness – mostly self-blocks, which White can take advantage of to deliver mate. In this case, most moves by the knight on d5 will threaten 2. Rf4# (now that d5 is guarded), but which is the correct one?
Mate in three
You have to find White’s key move, which will threaten to force mate in a further two moves. Again, Black’s defences to the threat will allow White to meet them with continuations that take advantage of the weaknesses they create – again self-blocks, but this time of the anticipatory variety (see commentary above). Three-movers are generally more difficult than two-movers, but this one is not so bad – all the white moves after the key are checks. You could also ask yourself: Is the Bh3 really needed to guard e6?
Any queries or constructive comments can be addressed to the author at david.friedgood@gmail.com.
Copyright in this article David Friedgood 2012/ChessBase
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