Termination of the following Term Rewriting System could be disproven:

Generalized rewrite system (where rules with free variables on rhs are allowed):
The TRS R consists of the following rules:

hd(cons) → X
tl(cons) → Y
natsadx(zeros)
zeroscons
incr(cons) → cons
adx(cons) → incr(cons)



GTRS
  ↳ CritRuleProof

Generalized rewrite system (where rules with free variables on rhs are allowed):
The TRS R consists of the following rules:

hd(cons) → X
tl(cons) → Y
natsadx(zeros)
zeroscons
incr(cons) → cons
adx(cons) → incr(cons)


The rule hd(cons) → X contains free variables in its right-hand side. Hence the TRS is not-terminating.