Certification Problem

Input (TPDB SRS_Relative/Waldmann_19/random-10)

The relative rewrite relation R/S is considered where R is the following TRS

a(c(b(x1))) → c(c(c(x1))) (1)
b(c(c(x1))) → a(a(b(x1))) (2)

and S is the following TRS.

c(c(c(x1))) → c(c(b(x1))) (3)
c(a(c(x1))) → b(a(b(x1))) (4)
b(c(a(x1))) → a(b(c(x1))) (5)

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by AProVE @ termCOMP 2023)

1 Closure Under Flat Contexts

Using the flat contexts

{a(☐), c(☐), b(☐)}

We obtain the transformed TRS
a(a(c(b(x1)))) → a(c(c(c(x1)))) (6)
c(a(c(b(x1)))) → c(c(c(c(x1)))) (7)
b(a(c(b(x1)))) → b(c(c(c(x1)))) (8)
a(b(c(c(x1)))) → a(a(a(b(x1)))) (9)
c(b(c(c(x1)))) → c(a(a(b(x1)))) (10)
b(b(c(c(x1)))) → b(a(a(b(x1)))) (11)
c(c(c(x1))) → c(c(b(x1))) (3)
a(c(a(c(x1)))) → a(b(a(b(x1)))) (12)
c(c(a(c(x1)))) → c(b(a(b(x1)))) (13)
b(c(a(c(x1)))) → b(b(a(b(x1)))) (14)
a(b(c(a(x1)))) → a(a(b(c(x1)))) (15)
c(b(c(a(x1)))) → c(a(b(c(x1)))) (16)
b(b(c(a(x1)))) → b(a(b(c(x1)))) (17)

1.1 Semantic Labeling

Root-labeling is applied.

We obtain the labeled TRS
aa(ac(cb(ba(x1)))) → ac(cc(cc(ca(x1)))) (18)
aa(ac(cb(bc(x1)))) → ac(cc(cc(cc(x1)))) (19)
aa(ac(cb(bb(x1)))) → ac(cc(cc(cb(x1)))) (20)
ca(ac(cb(ba(x1)))) → cc(cc(cc(ca(x1)))) (21)
ca(ac(cb(bc(x1)))) → cc(cc(cc(cc(x1)))) (22)
ca(ac(cb(bb(x1)))) → cc(cc(cc(cb(x1)))) (23)
ba(ac(cb(ba(x1)))) → bc(cc(cc(ca(x1)))) (24)
ba(ac(cb(bc(x1)))) → bc(cc(cc(cc(x1)))) (25)
ba(ac(cb(bb(x1)))) → bc(cc(cc(cb(x1)))) (26)
ab(bc(cc(ca(x1)))) → aa(aa(ab(ba(x1)))) (27)
ab(bc(cc(cc(x1)))) → aa(aa(ab(bc(x1)))) (28)
ab(bc(cc(cb(x1)))) → aa(aa(ab(bb(x1)))) (29)
cb(bc(cc(ca(x1)))) → ca(aa(ab(ba(x1)))) (30)
cb(bc(cc(cc(x1)))) → ca(aa(ab(bc(x1)))) (31)
cb(bc(cc(cb(x1)))) → ca(aa(ab(bb(x1)))) (32)
bb(bc(cc(ca(x1)))) → ba(aa(ab(ba(x1)))) (33)
bb(bc(cc(cc(x1)))) → ba(aa(ab(bc(x1)))) (34)
bb(bc(cc(cb(x1)))) → ba(aa(ab(bb(x1)))) (35)
cc(cc(ca(x1))) → cc(cb(ba(x1))) (36)
cc(cc(cc(x1))) → cc(cb(bc(x1))) (37)
cc(cc(cb(x1))) → cc(cb(bb(x1))) (38)
ac(ca(ac(ca(x1)))) → ab(ba(ab(ba(x1)))) (39)
ac(ca(ac(cc(x1)))) → ab(ba(ab(bc(x1)))) (40)
ac(ca(ac(cb(x1)))) → ab(ba(ab(bb(x1)))) (41)
cc(ca(ac(ca(x1)))) → cb(ba(ab(ba(x1)))) (42)
cc(ca(ac(cc(x1)))) → cb(ba(ab(bc(x1)))) (43)
cc(ca(ac(cb(x1)))) → cb(ba(ab(bb(x1)))) (44)
bc(ca(ac(ca(x1)))) → bb(ba(ab(ba(x1)))) (45)
bc(ca(ac(cc(x1)))) → bb(ba(ab(bc(x1)))) (46)
bc(ca(ac(cb(x1)))) → bb(ba(ab(bb(x1)))) (47)
ab(bc(ca(aa(x1)))) → aa(ab(bc(ca(x1)))) (48)
ab(bc(ca(ac(x1)))) → aa(ab(bc(cc(x1)))) (49)
ab(bc(ca(ab(x1)))) → aa(ab(bc(cb(x1)))) (50)
cb(bc(ca(aa(x1)))) → ca(ab(bc(ca(x1)))) (51)
cb(bc(ca(ac(x1)))) → ca(ab(bc(cc(x1)))) (52)
cb(bc(ca(ab(x1)))) → ca(ab(bc(cb(x1)))) (53)
bb(bc(ca(aa(x1)))) → ba(ab(bc(ca(x1)))) (54)
bb(bc(ca(ac(x1)))) → ba(ab(bc(cc(x1)))) (55)
bb(bc(ca(ab(x1)))) → ba(ab(bc(cb(x1)))) (56)

1.1.1 Rule Removal

Using the Knuth Bendix order with w0 = 1 and the following precedence and weight functions
prec(aa) = 7 weight(aa) = 5
prec(ac) = 5 weight(ac) = 4
prec(cb) = 4 weight(cb) = 3
prec(ba) = 0 weight(ba) = 9
prec(cc) = 6 weight(cc) = 5
prec(ca) = 3 weight(ca) = 7
prec(bc) = 2 weight(bc) = 7
prec(bb) = 1 weight(bb) = 5
prec(ab) = 8 weight(ab) = 1
all of the following rules can be deleted.
aa(ac(cb(ba(x1)))) → ac(cc(cc(ca(x1)))) (18)
aa(ac(cb(bc(x1)))) → ac(cc(cc(cc(x1)))) (19)
aa(ac(cb(bb(x1)))) → ac(cc(cc(cb(x1)))) (20)
ca(ac(cb(ba(x1)))) → cc(cc(cc(ca(x1)))) (21)
ca(ac(cb(bc(x1)))) → cc(cc(cc(cc(x1)))) (22)
ca(ac(cb(bb(x1)))) → cc(cc(cc(cb(x1)))) (23)
ba(ac(cb(ba(x1)))) → bc(cc(cc(ca(x1)))) (24)
ba(ac(cb(bc(x1)))) → bc(cc(cc(cc(x1)))) (25)
ba(ac(cb(bb(x1)))) → bc(cc(cc(cb(x1)))) (26)
ab(bc(cc(ca(x1)))) → aa(aa(ab(ba(x1)))) (27)
ab(bc(cc(cc(x1)))) → aa(aa(ab(bc(x1)))) (28)
ab(bc(cc(cb(x1)))) → aa(aa(ab(bb(x1)))) (29)
cb(bc(cc(ca(x1)))) → ca(aa(ab(ba(x1)))) (30)
cb(bc(cc(cc(x1)))) → ca(aa(ab(bc(x1)))) (31)
cb(bc(cc(cb(x1)))) → ca(aa(ab(bb(x1)))) (32)
bb(bc(cc(ca(x1)))) → ba(aa(ab(ba(x1)))) (33)
bb(bc(cc(cc(x1)))) → ba(aa(ab(bc(x1)))) (34)
bb(bc(cc(cb(x1)))) → ba(aa(ab(bb(x1)))) (35)
cc(cc(ca(x1))) → cc(cb(ba(x1))) (36)
cc(cc(cc(x1))) → cc(cb(bc(x1))) (37)
cc(cc(cb(x1))) → cc(cb(bb(x1))) (38)
ac(ca(ac(ca(x1)))) → ab(ba(ab(ba(x1)))) (39)
ac(ca(ac(cc(x1)))) → ab(ba(ab(bc(x1)))) (40)
ac(ca(ac(cb(x1)))) → ab(ba(ab(bb(x1)))) (41)
cc(ca(ac(ca(x1)))) → cb(ba(ab(ba(x1)))) (42)
cc(ca(ac(cc(x1)))) → cb(ba(ab(bc(x1)))) (43)
cc(ca(ac(cb(x1)))) → cb(ba(ab(bb(x1)))) (44)
bc(ca(ac(ca(x1)))) → bb(ba(ab(ba(x1)))) (45)
bc(ca(ac(cc(x1)))) → bb(ba(ab(bc(x1)))) (46)
bc(ca(ac(cb(x1)))) → bb(ba(ab(bb(x1)))) (47)
ab(bc(ca(aa(x1)))) → aa(ab(bc(ca(x1)))) (48)
ab(bc(ca(ac(x1)))) → aa(ab(bc(cc(x1)))) (49)
ab(bc(ca(ab(x1)))) → aa(ab(bc(cb(x1)))) (50)
cb(bc(ca(aa(x1)))) → ca(ab(bc(ca(x1)))) (51)
cb(bc(ca(ac(x1)))) → ca(ab(bc(cc(x1)))) (52)
cb(bc(ca(ab(x1)))) → ca(ab(bc(cb(x1)))) (53)
bb(bc(ca(aa(x1)))) → ba(ab(bc(ca(x1)))) (54)
bb(bc(ca(ac(x1)))) → ba(ab(bc(cc(x1)))) (55)
bb(bc(ca(ab(x1)))) → ba(ab(bc(cb(x1)))) (56)

1.1.1.1 R is empty

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