Automated Reasoning : First International Joint Conference IJCAR 2001 Siena Italy June 18–22 2001 Proceedings This book constitutes the refereed proceedings of the First International Joint Conference on Automated Reasoning IJCAR 2001 held in Siena Italy in June 2001. The 37 research papers and 19 system descriptions presented together with three invited contributions were carefully reviewed and selected from a total of 112 submissions. The book offers topical sections on description modal and temporal logics; saturation based theorem proving applications and data structures; logic programming and nonmonotonic reasoning; propositional satisfiability and quantified Boolean logic; logical frameworks higher order logic and interactive theorem proving; equational theorem proving and term rewriting; tableau sequent and natural deduction calculi and proof theory; automata specification verification and logics of programs; and nonclassical logics