Certification Problem
Input (TPDB TRS_Standard/Transformed_CSR_04/MYNAT_nokinds_L)
The rewrite relation of the following TRS is considered.
|
U11(tt) |
→ |
N |
(1) |
|
U21(tt) |
→ |
s(plus(N,M)) |
(2) |
|
U41(tt) |
→ |
plus(x(N,M),N) |
(3) |
|
and(tt) |
→ |
X |
(4) |
|
U31(tt) |
→ |
0 |
(5) |
| isNat |
→ |
tt |
(6) |
| isNat |
→ |
and(isNat) |
(7) |
| isNat |
→ |
isNat |
(8) |
|
plus(N,0) |
→ |
U11(isNat) |
(9) |
|
plus(N,s(M)) |
→ |
U21(and(isNat)) |
(10) |
|
x(N,0) |
→ |
U31(isNat) |
(11) |
|
x(N,s(M)) |
→ |
U41(and(isNat)) |
(12) |
Property / Task
Prove or disprove termination.Answer / Result
No.Proof (by ttt2 @ termCOMP 2023)
1 Loop
The following loop proves nontermination.
| t0
|
= |
U11(tt) |
|
→
|
U11(tt) |
|
= |
t1
|
where t1 =
t0σ
and
σ =
{N/U11(tt)}