Certification Problem

Input (TPDB TRS_Standard/SK90/2.01)

The rewrite relation of the following TRS is considered.

i(0) 0 (1)
+(0,y) y (2)
+(x,0) x (3)
i(i(x)) x (4)
+(i(x),x) 0 (5)
+(x,i(x)) 0 (6)
i(+(x,y)) +(i(x),i(y)) (7)
+(x,+(y,z)) +(+(x,y),z) (8)
+(+(x,i(y)),y) x (9)
+(+(x,y),i(y)) x (10)

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by AProVE @ termCOMP 2023)

1 Rule Removal

Using the
prec(i) = 1 stat(i) = lex
prec(0) = 0 stat(0) = lex
prec(+) = 0 stat(+) = lex

π(i) = [1]
π(0) = []
π(+) = [2,1]

all of the following rules can be deleted.
i(0) 0 (1)
+(0,y) y (2)
+(x,0) x (3)
i(i(x)) x (4)
+(i(x),x) 0 (5)
+(x,i(x)) 0 (6)
i(+(x,y)) +(i(x),i(y)) (7)
+(x,+(y,z)) +(+(x,y),z) (8)
+(+(x,i(y)),y) x (9)
+(+(x,y),i(y)) x (10)

1.1 R is empty

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