Certification Problem

Input (TPDB SRS_Standard/Zantema_06/14)

The rewrite relation of the following TRS is considered.

a(a(x1)) b(a(b(x1))) (1)
b(b(x1)) a(c(b(x1))) (2)
c(c(x1)) c(b(a(x1))) (3)
a(b(x1)) b(a(x1)) (4)
b(c(x1)) c(x1) (5)

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by AProVE @ termCOMP 2023)

1 Dependency Pair Transformation

The following set of initial dependency pairs has been identified.
a#(a(x1)) b#(a(b(x1))) (6)
a#(a(x1)) a#(b(x1)) (7)
a#(a(x1)) b#(x1) (8)
b#(b(x1)) a#(c(b(x1))) (9)
b#(b(x1)) c#(b(x1)) (10)
c#(c(x1)) c#(b(a(x1))) (11)
c#(c(x1)) b#(a(x1)) (12)
c#(c(x1)) a#(x1) (13)
a#(b(x1)) b#(a(x1)) (14)
a#(b(x1)) a#(x1) (15)

1.1 Reduction Pair Processor

Using the matrix interpretations of dimension 3 with strict dimension 1 over the arctic semiring over the naturals
[a#(x1)] =
1
-∞
-∞
+
0 0 0
-∞ -∞ -∞
-∞ -∞ -∞
· x1
[a(x1)] =
0
0
0
+
0 -∞ -∞
1 0 0
0 -∞ -∞
· x1
[b#(x1)] =
1
-∞
-∞
+
0 0 0
-∞ -∞ -∞
-∞ -∞ -∞
· x1
[b(x1)] =
0
0
0
+
0 -∞ -∞
1 0 0
0 -∞ 0
· x1
[c(x1)] =
0
0
1
+
0 -∞ -∞
0 0 0
1 0 0
· x1
[c#(x1)] =
0
-∞
-∞
+
0 -∞ 0
-∞ -∞ -∞
-∞ -∞ -∞
· x1
the pair
c#(c(x1)) c#(b(a(x1))) (11)
could be deleted.

1.1.1 Reduction Pair Processor

Using the matrix interpretations of dimension 3 with strict dimension 1 over the arctic semiring over the naturals
[a#(x1)] =
0
-∞
-∞
+
0 0 -∞
-∞ -∞ -∞
-∞ -∞ -∞
· x1
[a(x1)] =
0
1
0
+
-∞ -∞ -∞
0 0 0
-∞ -∞ -∞
· x1
[b#(x1)] =
0
-∞
-∞
+
0 -∞ 0
-∞ -∞ -∞
-∞ -∞ -∞
· x1
[b(x1)] =
0
1
0
+
0 -∞ 0
0 0 0
0 -∞ 0
· x1
[c(x1)] =
0
0
1
+
0 -∞ 0
0 -∞ 0
0 0 0
· x1
[c#(x1)] =
-∞
-∞
-∞
+
0 -∞ 0
-∞ -∞ -∞
-∞ -∞ -∞
· x1
the pairs
a#(a(x1)) b#(a(b(x1))) (6)
c#(c(x1)) b#(a(x1)) (12)
a#(b(x1)) b#(a(x1)) (14)
could be deleted.

1.1.1.1 Reduction Pair Processor

Using the matrix interpretations of dimension 3 with strict dimension 1 over the arctic semiring over the naturals
[a#(x1)] =
0
-∞
-∞
+
-∞ 0 0
-∞ -∞ -∞
-∞ -∞ -∞
· x1
[a(x1)] =
0
0
1
+
0 0 0
-∞ -∞ 0
0 0 0
· x1
[b(x1)] =
0
-∞
1
+
0 0 0
0 0 0
0 0 0
· x1
[b#(x1)] =
0
-∞
-∞
+
-∞ 0 0
-∞ -∞ -∞
-∞ -∞ -∞
· x1
[c(x1)] =
1
-∞
-∞
+
0 0 0
-∞ -∞ -∞
-∞ -∞ -∞
· x1
[c#(x1)] =
1
-∞
-∞
+
0 0 0
-∞ -∞ -∞
-∞ -∞ -∞
· x1
the pair
b#(b(x1)) a#(c(b(x1))) (9)
could be deleted.

1.1.1.1.1 Reduction Pair Processor

Using the matrix interpretations of dimension 3 with strict dimension 1 over the arctic semiring over the naturals
[a#(x1)] =
1
-∞
-∞
+
0 0 0
-∞ -∞ -∞
-∞ -∞ -∞
· x1
[a(x1)] =
1
0
-∞
+
1 0 1
0 -∞ 0
0 -∞ 0
· x1
[b(x1)] =
1
0
-∞
+
0 0 1
-∞ 0 0
-∞ 0 0
· x1
[b#(x1)] =
1
-∞
-∞
+
0 0 1
-∞ -∞ -∞
-∞ -∞ -∞
· x1
[c#(x1)] =
-∞
-∞
-∞
+
0 1 0
-∞ -∞ -∞
-∞ -∞ -∞
· x1
[c(x1)] =
0
1
0
+
-∞ 0 0
0 1 0
-∞ 0 0
· x1
the pair
c#(c(x1)) a#(x1) (13)
could be deleted.

1.1.1.1.1.1 Dependency Graph Processor

The dependency pairs are split into 1 component.