Charles Wallis Computation and cognition. 177-193 2003 15 J. Exp. Theor. Artif. Intell. 2 http://taylorandfrancis.metapress.com/openurl.asp?genre=article&issn=0952-813x&volume=15&issue=2&spage=177 db/journals/jetai/jetai15.html#Wallis03