 Logic was introduced into AI research as early as 1958 , by John McCarthy in his <unk> <unk> proposal . In 1963 , J. Alan Robinson had discovered a simple method to implement deduction on computers , the resolution and unification algorithm . However , straightforward <unk> , like those attempted by McCarthy and his students in the late 60s , were especially <unk> : the programs required astronomical numbers of steps to prove simple theorems . A more fruitful approach to logic was developed in the 1970s by Robert Kowalski at the University of Edinburgh , and soon this led to the collaboration with French researchers Alain <unk> and Philippe <unk> who created the successful logic programming language Prolog . Prolog uses a subset of logic ( Horn clauses , closely related to " rules " and " production rules " ) that permit <unk> computation . Rules would continue to be influential , providing a foundation for Edward Feigenbaum 's expert systems and the continuing work by Allen Newell and Herbert A. Simon that would lead to <unk> and their unified theories of cognition . 
