Certification Problem

Input (TPDB TRS_Standard/Transformed_CSR_04/Ex1_2_Luc02c_Z)

The rewrite relation of the following TRS is considered.

2nd(cons(X,n__cons(Y,Z))) activate(Y) (1)
from(X) cons(X,n__from(s(X))) (2)
cons(X1,X2) n__cons(X1,X2) (3)
from(X) n__from(X) (4)
activate(n__cons(X1,X2)) cons(X1,X2) (5)
activate(n__from(X)) from(X) (6)
activate(X) X (7)

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by AProVE @ termCOMP 2023)

1 Rule Removal

Using the linear polynomial interpretation over the naturals
[2nd(x1)] = 1 + 2 · x1
[cons(x1, x2)] = 1 + 1 · x1 + 1 · x2
[n__cons(x1, x2)] = 1 · x1 + 1 · x2
[activate(x1)] = 2 + 2 · x1
[from(x1)] = 1 + 2 · x1
[n__from(x1)] = 1 · x1
[s(x1)] = 1 · x1
all of the following rules can be deleted.
2nd(cons(X,n__cons(Y,Z))) activate(Y) (1)
cons(X1,X2) n__cons(X1,X2) (3)
from(X) n__from(X) (4)
activate(n__cons(X1,X2)) cons(X1,X2) (5)
activate(n__from(X)) from(X) (6)
activate(X) X (7)

1.1 Rule Removal

Using the
prec(from) = 1 stat(from) = mul
prec(cons) = 0 stat(cons) = mul

π(from) = [1]
π(cons) = [1,2]
π(n__from) = 1
π(s) = 1

all of the following rules can be deleted.
from(X) cons(X,n__from(s(X))) (2)

1.1.1 R is empty

There are no rules in the TRS. Hence, it is terminating.