Certification Problem
Input (TPDB TRS_Standard/Secret_06_TRS/gen-18)
The rewrite relation of the following TRS is considered.
b(b(y,z),c(a,a,a)) |
→ |
f(c(z,y,z)) |
(1) |
f(b(b(a,z),c(a,x,y))) |
→ |
z |
(2) |
c(y,x,f(z)) |
→ |
b(f(b(z,x)),z) |
(3) |
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#(b(y,z),c(a,a,a)) |
→ |
f#(c(z,y,z)) |
(4) |
b#(b(y,z),c(a,a,a)) |
→ |
c#(z,y,z) |
(5) |
c#(y,x,f(z)) |
→ |
b#(f(b(z,x)),z) |
(6) |
c#(y,x,f(z)) |
→ |
f#(b(z,x)) |
(7) |
c#(y,x,f(z)) |
→ |
b#(z,x) |
(8) |
1.1 Dependency Graph Processor
The dependency pairs are split into 1
component.
-
The
1st
component contains the
pair
b#(b(y,z),c(a,a,a)) |
→ |
c#(z,y,z) |
(5) |
c#(y,x,f(z)) |
→ |
b#(f(b(z,x)),z) |
(6) |
c#(y,x,f(z)) |
→ |
b#(z,x) |
(8) |
1.1.1 Reduction Pair Processor
Using the matrix interpretations of dimension 1 with strict dimension 1 over the arctic semiring over the naturals
[b#(x1, x2)] |
= |
+ · x1 + · x2
|
[b(x1, x2)] |
= |
+ · x1 + · x2
|
[c(x1, x2, x3)] |
= |
+ · x1 + · x2 + · x3
|
[a] |
= |
|
[c#(x1, x2, x3)] |
= |
+ · x1 + · x2 + · x3
|
[f(x1)] |
= |
+ · x1
|
the
pair
c#(y,x,f(z)) |
→ |
b#(z,x) |
(8) |
could be deleted.
1.1.1.1 Reduction Pair Processor
Using the matrix interpretations of dimension 2 with strict dimension 1 over the integers
[b#(x1, x2)] |
= |
+ · x1 + · x2
|
[b(x1, x2)] |
= |
+ · x1 + · x2
|
[c(x1, x2, x3)] |
= |
+ · x1 + · x2 + · x3
|
[a] |
= |
|
[c#(x1, x2, x3)] |
= |
+ · x1 + · x2 + · x3
|
[f(x1)] |
= |
+ · x1
|
the
pair
b#(b(y,z),c(a,a,a)) |
→ |
c#(z,y,z) |
(5) |
could be deleted.
1.1.1.1.1 Size-Change Termination
Using size-change termination in combination with
the subterm criterion
one obtains the following initial size-change graphs.
c#(y,x,f(z)) |
→ |
b#(f(b(z,x)),z) |
(6) |
|
3 |
> |
2 |
As there is no critical graph in the transitive closure, there are no infinite chains.