(0) Obligation:
Generalized rewrite system (where rules with free variables on rhs are allowed):
The TRS R consists of the following rules:
tail(cons(X)) → XS
zeros → cons(0)
(1) CritRuleProof (EQUIVALENT transformation)
The rule tail(cons(X)) → XS contains free variables in its right-hand side. Hence the TRS is not-terminating.
(2) FALSE