NO Problem 1: (VAR v_NonEmpty:S X:S XS:S) (RULES head(cons(X:S)) -> X:S incr(cons(X:S)) -> cons(s(X:S)) nats -> cons(0) odds -> incr(pairs) pairs -> cons(0) tail(cons(X:S)) -> XS:S ) Problem 1: Extra Variables Processor: -> Rules: head(cons(X:S)) -> X:S incr(cons(X:S)) -> cons(s(X:S)) nats -> cons(0) odds -> incr(pairs) pairs -> cons(0) tail(cons(X:S)) -> XS:S -> The system has extra variables. The problem is infinite.