YES Termination Proof

Termination Proof

by ttt2 (version ttt2 1.15)

Input

The rewrite relation of the following TRS is considered.

a(a(x0)) b(b(b(x0)))
b(x0) c(c(d(x0)))
c(x0) d(d(d(x0)))
b(c(x0)) c(b(x0))
b(c(d(x0))) a(x0)

Proof

1 Rule Removal

Using the linear polynomial interpretation over the arctic semiring over the integers
[b(x1)] = 4 · x1 + -∞
[c(x1)] = 2 · x1 + -∞
[a(x1)] = 6 · x1 + -∞
[d(x1)] = 0 · x1 + -∞
the rules
a(a(x0)) b(b(b(x0)))
b(x0) c(c(d(x0)))
b(c(x0)) c(b(x0))
b(c(d(x0))) a(x0)
remain.

1.1 Rule Removal

Using the linear polynomial interpretation over the arctic semiring over the integers
[b(x1)] = 2 · x1 + -∞
[c(x1)] = 0 · x1 + -∞
[a(x1)] = 3 · x1 + -∞
[d(x1)] = 1 · x1 + -∞
the rules
a(a(x0)) b(b(b(x0)))
b(c(x0)) c(b(x0))
b(c(d(x0))) a(x0)
remain.

1.1.1 Rule Removal

Using the linear polynomial interpretation over the arctic semiring over the integers
[b(x1)] = 0 · x1 + -∞
[c(x1)] = 4 · x1 + -∞
[a(x1)] = 0 · x1 + -∞
[d(x1)] = 15 · x1 + -∞
the rules
a(a(x0)) b(b(b(x0)))
b(c(x0)) c(b(x0))
remain.

1.1.1.1 Rule Removal

Using the linear polynomial interpretation over the arctic semiring over the integers
[b(x1)] = 2 · x1 + -∞
[c(x1)] = 2 · x1 + -∞
[a(x1)] = 8 · x1 + -∞
the rule
b(c(x0)) c(b(x0))
remains.

1.1.1.1.1 Rule Removal

Using the Knuth Bendix order with w0 = 1 and the following precedence and weight function
prec(c) = 0 weight(c) = 1
prec(b) = 1 weight(b) = 1
all rules could be removed.

1.1.1.1.1.1 R is empty

There are no rules in the TRS. Hence, it is terminating.