Certification Problem
Input (TPDB TRS_Standard/AProVE_10/isList)
The rewrite relation of the following TRS is considered.
|
f(tt,x) |
→ |
f(isList(x),x) |
(1) |
|
isList(Cons(x,xs)) |
→ |
isList(xs) |
(2) |
|
isList(nil) |
→ |
tt |
(3) |
Property / Task
Prove or disprove termination.Answer / Result
No.Proof (by ttt2 @ termCOMP 2023)
1 Loop
The following loop proves nontermination.
| t0
|
= |
f(isList(nil),nil) |
|
→
|
f(tt,nil) |
|
→
|
f(isList(nil),nil) |
|
= |
t2
|
where t2 =
t0