Certification Problem

Input (TPDB SRS_Standard/Secret_07_SRS/x08)

The rewrite relation of the following TRS is considered.

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

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.
b#(a(a(b(x1)))) a#(a(a(a(b(b(b(x1))))))) (5)
b#(a(a(b(x1)))) a#(a(a(b(b(b(x1)))))) (6)
b#(a(a(b(x1)))) a#(a(b(b(b(x1))))) (7)
b#(a(a(b(x1)))) a#(b(b(b(x1)))) (8)
b#(a(a(b(x1)))) b#(b(b(x1))) (9)
b#(a(a(b(x1)))) b#(b(x1)) (10)
a#(a(a(a(x1)))) b#(x1) (11)

1.1 Reduction Pair Processor

Using the matrix interpretations of dimension 3 with strict dimension 1 over the arctic semiring over the naturals
[b#(x1)] =
0
-∞
-∞
+
0 0 1
-∞ -∞ -∞
-∞ -∞ -∞
· x1
[a(x1)] =
1
0
0
+
0 -∞ 0
1 0 0
0 0 0
· x1
[b(x1)] =
0
-∞
0
+
-∞ 0 -∞
-∞ 0 -∞
0 1 0
· x1
[a#(x1)] =
0
-∞
-∞
+
0 0 0
-∞ -∞ -∞
-∞ -∞ -∞
· x1
the pairs
b#(a(a(b(x1)))) a#(a(b(b(b(x1))))) (7)
b#(a(a(b(x1)))) a#(b(b(b(x1)))) (8)
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
[b#(x1)] =
-∞
-∞
-∞
+
1 0 0
-∞ -∞ -∞
-∞ -∞ -∞
· x1
[a(x1)] =
-∞
-∞
-∞
+
0 1 0
-∞ 0 0
0 0 0
· x1
[b(x1)] =
-∞
-∞
-∞
+
0 0 1
0 0 1
-∞ -∞ 0
· x1
[a#(x1)] =
-∞
-∞
-∞
+
0 0 1
-∞ -∞ -∞
-∞ -∞ -∞
· x1
the pairs
b#(a(a(b(x1)))) b#(b(b(x1))) (9)
b#(a(a(b(x1)))) b#(b(x1)) (10)
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
[b#(x1)] =
-∞
-∞
-∞
+
0 0 0
-∞ -∞ -∞
-∞ -∞ -∞
· x1
[a(x1)] =
-∞
0
-∞
+
0 -∞ 0
1 0 -∞
0 0 0
· x1
[b(x1)] =
-∞
-∞
-∞
+
0 0 1
-∞ -∞ 1
-∞ -∞ 0
· x1
[a#(x1)] =
0
-∞
-∞
+
0 0 -∞
-∞ -∞ -∞
-∞ -∞ -∞
· x1
the pair
a#(a(a(a(x1)))) b#(x1) (11)
could be deleted.

1.1.1.1.1 Dependency Graph Processor

The dependency pairs are split into 0 components.