Certification Problem
Input (TPDB TRS_Standard/Transformed_CSR_04/MYNAT_nosorts-noand_L)
The rewrite relation of the following TRS is considered.
U12(tt) |
→ |
s(plus(N,M)) |
(1) |
U22(tt) |
→ |
plus(x(N,M),N) |
(2) |
U11(tt) |
→ |
U12(tt) |
(3) |
U21(tt) |
→ |
U22(tt) |
(4) |
plus(N,0) |
→ |
N |
(5) |
plus(N,s(M)) |
→ |
U11(tt) |
(6) |
x(N,0) |
→ |
0 |
(7) |
x(N,s(M)) |
→ |
U21(tt) |
(8) |
Property / Task
Prove or disprove termination.Answer / Result
No.Proof (by ttt2 @ termCOMP 2023)
1 Loop
The following loop proves nontermination.
t0
|
= |
U12(tt) |
|
→
|
s(plus(U12(tt),M)) |
|
= |
t1
|
where t1 =
C[t0σ]
and
σ =
{N/U12(tt)}
and
C = s(plus(☐,M))