Certification Problem
Input (TPDB TRS_Outermost/Strategy_outermost_added_08/LengthOfFiniteLists_complete_L)
The rewrite relation of the following TRS is considered.
U61(tt) |
→ |
s(length(L)) |
(1) |
and(tt) |
→ |
X |
(2) |
zeros |
→ |
cons(0) |
(3) |
U11(tt) |
→ |
U12(isNatList) |
(4) |
U12(tt) |
→ |
tt |
(5) |
U21(tt) |
→ |
U22(isNat) |
(6) |
U22(tt) |
→ |
tt |
(7) |
U31(tt) |
→ |
U32(isNatList) |
(8) |
U32(tt) |
→ |
tt |
(9) |
U41(tt) |
→ |
U42(isNat) |
(10) |
U42(tt) |
→ |
U43(isNatIList) |
(11) |
U43(tt) |
→ |
tt |
(12) |
U51(tt) |
→ |
U52(isNat) |
(13) |
U52(tt) |
→ |
U53(isNatList) |
(14) |
U53(tt) |
→ |
tt |
(15) |
isNat |
→ |
tt |
(16) |
isNat |
→ |
U11(isNatIListKind) |
(17) |
isNat |
→ |
U21(isNatKind) |
(18) |
isNatIList |
→ |
U31(isNatIListKind) |
(19) |
isNatIList |
→ |
tt |
(20) |
isNatIList |
→ |
U41(and(isNatKind)) |
(21) |
isNatIListKind |
→ |
tt |
(22) |
isNatIListKind |
→ |
and(isNatKind) |
(23) |
isNatKind |
→ |
tt |
(24) |
isNatKind |
→ |
isNatIListKind |
(25) |
isNatKind |
→ |
isNatKind |
(26) |
isNatList |
→ |
tt |
(27) |
isNatList |
→ |
U51(and(isNatKind)) |
(28) |
length(nil) |
→ |
0 |
(29) |
length(cons(N)) |
→ |
U61(and(and(isNatList))) |
(30) |
The evaluation strategy is outermostProperty / Task
Prove or disprove termination.Answer / Result
No.Proof (by AProVE @ termCOMP 2023)
1 Loop
The following loop proves nontermination.
t0
|
= |
U61(tt) |
|
→
|
s(length(U61(tt))) |
|
= |
t1
|
where t1 =
C[t0]
and
C = s(length(☐))