Sandy Vanderbleek on Peter Norvig's Correcting A Widespread Error in Unification Algorithms

New York - May 14th, 2018


Peter Norvig found an error in the unification algorithm presented in his AI textbooks and several others and wrote a brief paper about it. While his paper focuses on Lisp implementations of higher-order unification, I will restrict the problem to syntactic propositional unification and present the erroneous and correct algorithm in a pattern and substitution notation.


Sandy Vanderbleek ( has been a software engineer in industry and academia for 10 years. He is currently a Data Scientist at Publicis Media ( His research interests are formal methods and computational logic with applications to industry.



TwoSigma The New York Chapter would like to thank TwoSigma for helping to make this meetup possible.