Chess Puzzle of the Week (121): Solution

A popular idea amongst problemists is the Four Corners theme, in which all four corners of the board are used within the solution, possibly also including the try play.

This position, taken from an article by Amatzia Avni in the March 2021 issue of CHESS, is from a game between the great Ulf Andersson and Chiel van Oosterom (Haarlem 2012).

Ulf chose the wrong corner for his queen, playing 51. Qa8?, with the idea of Rh8 followed by mate, but Black was able to defend and the game resulted in a draw.

Instead he could have won using some nifty geometry: 51. Qa1! Rf6 52. Qh1! (heading for h8) 52… Qh6 53. Rg8+!.

If you found the solution, Euclid would have been proud of you.