GO is pspace hard

A great deal of effort has been spent in the search for optimal and computationally feasible game strategies. In some cases (e.g. Bridge-it, Nim), such strategies have been found, \vhile in others the search has been unsuccessful. Recently, it has become possible to provide compelling evidence that such strategies may not always exist. Even and Tarjan [1] and Schaefer [2] have shown that determining which player has a winning strategy in certain combinatorial games is a polynomial space complete problem [3]. (See also [4;5].)