YES Termination Proof

Termination Proof

by ttt2 (version ttt2 1.15)

Input

The rewrite relation of the following TRS is considered.

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

Proof

1 Rule Removal

Using the linear polynomial interpretation over the naturals
[a(x1)] = 1 · x1 + 13
[c(x1)] = 13 · x1 + 5
[d(x1)] = 13 · x1 + 4
[b(x1)] = 1 · x1 + 1
the rules
a(d(x0)) d(b(x0))
b(d(b(x0))) a(c(x0))
remain.

1.1 Rule Removal

Using the linear polynomial interpretation over (2 x 2)-matrices with strict dimension 1 over the arctic semiring over the integers
[a(x1)] =
1 0
-∞ 2
· x1 +
-∞ -∞
-∞ -∞
[c(x1)] =
1 3
2 2
· x1 +
-∞ -∞
-∞ -∞
[d(x1)] =
1 0
3 3
· x1 +
-∞ -∞
-∞ -∞
[b(x1)] =
2 2
2 2
· x1 +
-∞ -∞
-∞ -∞
the rule
a(d(x0)) d(b(x0))
remains.

1.1.1 Rule Removal

Using the linear polynomial interpretation over (2 x 2)-matrices with strict dimension 1 over the arctic semiring over the integers
[a(x1)] =
1 0
0 0
· x1 +
-∞ -∞
-∞ -∞
[d(x1)] =
0 0
-∞ -∞
· x1 +
-∞ -∞
-∞ -∞
[b(x1)] =
0 -∞
0 -∞
· x1 +
-∞ -∞
-∞ -∞
all rules could be removed.

1.1.1.1 R is empty

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