NO Nontermination Proof

Nontermination Proof

by ttt2 (version ttt2 1.15)

Input

The rewrite relation of the following TRS is considered.

Begin(b(c(x0))) → Wait(Right1(x0))
Begin(c(x0)) → Wait(Right2(x0))
Right1(a(End(x0))) → Left(c(c(a(b(a(End(x0)))))))
Right2(a(b(End(x0)))) → Left(c(c(a(b(a(End(x0)))))))
Right1(a(x0)) → Aa(Right1(x0))
Right2(a(x0)) → Aa(Right2(x0))
Right1(b(x0)) → Ab(Right1(x0))
Right2(b(x0)) → Ab(Right2(x0))
Right1(c(x0)) → Ac(Right1(x0))
Right2(c(x0)) → Ac(Right2(x0))
Aa(Left(x0)) → Left(a(x0))
Ab(Left(x0)) → Left(b(x0))
Ac(Left(x0)) → Left(c(x0))
Wait(Left(x0)) → Begin(x0)
a(x0) → x0
a(b(c(x0))) → c(c(a(b(a(x0)))))
c(x0) → x0

Proof

1 Loop

The following loop proves nontermination.

t0 = Begin(c(a(b(End(x32916)))))
→ε Wait(Right2(a(b(End(x32916)))))
→1 Wait(Left(c(c(a(b(a(End(x32916))))))))
→ε Begin(c(c(a(b(a(End(x32916)))))))
→1 Begin(c(a(b(a(End(x32916))))))
→1.1.1.1 Begin(c(a(b(End(x32916)))))
= t5
where t5 = t0σ and σ = {x32916/x32916}