Certification Problem

Input (TPDB TRS_Relative/INVY_15/#3.37_rand)

The relative rewrite relation R/S is considered where R is the following TRS

not(true) → false (1)
not(false) → true (2)
evenodd(x,0) → not(evenodd(x,s(0))) (3)
evenodd(0,s(0)) → false (4)
evenodd(s(x),s(0)) → evenodd(x,0) (5)

and S is the following TRS.

rand(x) → rand(s(x)) (6)
rand(x) → x (7)

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by AProVE @ termCOMP 2023)

1 Rule Removal

Using the linear polynomial interpretation over the naturals
[not(x1)] = 1 · x1
[true] = 1
[false] = 1
[evenodd(x1, x2)] = 1 + 1 · x1 + 1 · x2
[0] = 0
[s(x1)] = 1 · x1
[rand(x1)] = 1 + 1 · x1
all of the following rules can be deleted.
rand(x) → x (7)

1.1 Rule Removal

Using the linear polynomial interpretation over the naturals
[not(x1)] = 1 · x1
[true] = 1
[false] = 1
[evenodd(x1, x2)] = 1 + 1 · x1 + 1 · x2
[0] = 1
[s(x1)] = 1 · x1
[rand(x1)] = 1 · x1
all of the following rules can be deleted.
evenodd(0,s(0)) → false (4)

1.1.1 Rule Removal

Using the matrix interpretations of dimension 2 with strict dimension 1 over the integers
[not(x1)] =
0
0
+
1 1
0 1
· x1
[true] =
0
1
[false] =
0
1
[evenodd(x1, x2)] =
0
0
+
1 1
0 0
· x1 +
1 1
1 1
· x2
[0] =
0
0
[s(x1)] =
0
0
+
1 0
1 1
· x1
[rand(x1)] =
1
1
+
1 0
1 0
· x1
all of the following rules can be deleted.
not(true) → false (1)
not(false) → true (2)

1.1.1.1 Rule Removal

Using the matrix interpretations of dimension 2 with strict dimension 1 over the integers
[evenodd(x1, x2)] =
0
0
+
1 1
1 0
· x1 +
1 0
1 0
· x2
[0] =
0
0
[not(x1)] =
0
0
+
1 0
0 0
· x1
[s(x1)] =
0
1
+
1 0
1 1
· x1
[rand(x1)] =
1
1
+
1 0
1 0
· x1
all of the following rules can be deleted.
evenodd(s(x),s(0)) → evenodd(x,0) (5)

1.1.1.1.1 Rule Removal

Using the matrix interpretations of dimension 2 with strict dimension 1 over the integers
[evenodd(x1, x2)] =
0
0
+
1 1
1 1
· x1 +
1 1
1 0
· x2
[0] =
0
1
[not(x1)] =
0
0
+
1 0
0 0
· x1
[s(x1)] =
0
0
+
1 0
0 0
· x1
[rand(x1)] =
1
1
+
1 1
1 1
· x1
all of the following rules can be deleted.
evenodd(x,0) → not(evenodd(x,s(0))) (3)

1.1.1.1.1.1 R is empty

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