Certification Problem

Input (TPDB TRS_Standard/SK90/2.27)

The rewrite relation of the following TRS is considered.

fib(0) 0 (1)
fib(s(0)) s(0) (2)
fib(s(s(0))) s(0) (3)
fib(s(s(x))) sp(g(x)) (4)
g(0) pair(s(0),0) (5)
g(s(0)) pair(s(0),s(0)) (6)
g(s(x)) np(g(x)) (7)
sp(pair(x,y)) +(x,y) (8)
np(pair(x,y)) pair(+(x,y),x) (9)
+(x,0) x (10)
+(x,s(y)) s(+(x,y)) (11)

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by NaTT @ termCOMP 2023)

1 Dependency Pair Transformation

The following set of initial dependency pairs has been identified.
+#(x,s(y)) +#(x,y) (12)
fib#(s(s(x))) sp#(g(x)) (13)
fib#(s(s(x))) g#(x) (14)
sp#(pair(x,y)) +#(x,y) (15)
g#(s(x)) np#(g(x)) (16)
np#(pair(x,y)) +#(x,y) (17)
g#(s(x)) g#(x) (18)

1.1 Dependency Graph Processor

The dependency pairs are split into 2 components.