Certification Problem

Input (TPDB TRS_Standard/Mixed_TRS/gcd_triple)

The rewrite relation of the following TRS is considered.

min(x,0) 0 (1)
min(0,y) 0 (2)
min(s(x),s(y)) s(min(x,y)) (3)
max(x,0) x (4)
max(0,y) y (5)
max(s(x),s(y)) s(max(x,y)) (6)
-(x,0) x (7)
-(s(x),s(y)) -(x,y) (8)
gcd(s(x),s(y),z) gcd(-(max(x,y),min(x,y)),s(min(x,y)),z) (9)
gcd(x,s(y),s(z)) gcd(x,-(max(y,z),min(y,z)),s(min(y,z))) (10)
gcd(s(x),y,s(z)) gcd(-(max(x,z),min(x,z)),y,s(min(x,z))) (11)
gcd(x,0,0) x (12)
gcd(0,y,0) y (13)
gcd(0,0,z) z (14)

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by ttt2 @ termCOMP 2023)

1 Dependency Pair Transformation

The following set of initial dependency pairs has been identified.
min#(s(x),s(y)) min#(x,y) (15)
max#(s(x),s(y)) max#(x,y) (16)
-#(s(x),s(y)) -#(x,y) (17)
gcd#(s(x),s(y),z) min#(x,y) (18)
gcd#(s(x),s(y),z) max#(x,y) (19)
gcd#(s(x),s(y),z) -#(max(x,y),min(x,y)) (20)
gcd#(s(x),s(y),z) gcd#(-(max(x,y),min(x,y)),s(min(x,y)),z) (21)
gcd#(x,s(y),s(z)) min#(y,z) (22)
gcd#(x,s(y),s(z)) max#(y,z) (23)
gcd#(x,s(y),s(z)) -#(max(y,z),min(y,z)) (24)
gcd#(x,s(y),s(z)) gcd#(x,-(max(y,z),min(y,z)),s(min(y,z))) (25)
gcd#(s(x),y,s(z)) min#(x,z) (26)
gcd#(s(x),y,s(z)) max#(x,z) (27)
gcd#(s(x),y,s(z)) -#(max(x,z),min(x,z)) (28)
gcd#(s(x),y,s(z)) gcd#(-(max(x,z),min(x,z)),y,s(min(x,z))) (29)

1.1 Dependency Graph Processor

The dependency pairs are split into 4 components.