Chess Problems by Computer

by François Labelle

In December 2003, I wrote a program to search for chess games that are completely determined by the last move. Among other chess problems, the search uncovered this brain-teaser:

Black mates White on Black's 5th move by playing a rook, but the rook itself does not attack White's king. How did the game go? (the solution is unique)

Since then I improved my program and used it to search for other types of chess problems.

Chess problems

Chess statistics

As a byproduct of the searches, I also get some statistics on the first few plies.

Plot of chess statistics

Plot of chess statistics

The curves "all games", "distinct positions", and "uniquely realizable diagrams" all start with the sequence 1,20,400 and eventually drop to zero.


last updated: December 22, 2016