Sir: William Hartston writes ("It calculates 1 billion chess moves every second, but it's still not as bright as you", 13 February) that Shannon's idea of searching through a list of likely moves has formed the basis for all computer chess programs. Although this brute force approach is true for commercial systems, it is not true for work in artificial intelligence research laboratories.
Work by Herb Simon and his colleagues over many years has developed cognitive models of how people perceive the chess board using patterns. Some programs can even claim to understand the game to some degree although not, as yet, as well as grandmasters.
Department of Computer Studies
University of Glamorgan
Pontypridd, Mid Glamorgan