Certification Problem

Input (TPDB SRS_Relative/Waldmann_19/random-41)

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

a(a(b(x1))) c(b(c(x1))) (1)
b(c(b(x1))) a(b(c(x1))) (2)
a(a(b(x1))) c(a(b(x1))) (3)

and S is the following TRS.

c(a(c(x1))) c(b(b(x1))) (4)
c(b(c(x1))) c(c(b(x1))) (5)
b(a(b(x1))) c(c(b(x1))) (6)
a(c(b(x1))) c(c(c(x1))) (7)

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by AProVE @ termCOMP 2023)

1 Closure Under Flat Contexts

Using the flat contexts

{a(), b(), c()}

We obtain the transformed TRS
a(a(a(b(x1)))) a(c(b(c(x1)))) (8)
b(a(a(b(x1)))) b(c(b(c(x1)))) (9)
c(a(a(b(x1)))) c(c(b(c(x1)))) (10)
a(b(c(b(x1)))) a(a(b(c(x1)))) (11)
b(b(c(b(x1)))) b(a(b(c(x1)))) (12)
c(b(c(b(x1)))) c(a(b(c(x1)))) (13)
a(a(a(b(x1)))) a(c(a(b(x1)))) (14)
b(a(a(b(x1)))) b(c(a(b(x1)))) (15)
c(a(a(b(x1)))) c(c(a(b(x1)))) (16)
c(a(c(x1))) c(b(b(x1))) (4)
c(b(c(x1))) c(c(b(x1))) (5)
a(b(a(b(x1)))) a(c(c(b(x1)))) (17)
b(b(a(b(x1)))) b(c(c(b(x1)))) (18)
c(b(a(b(x1)))) c(c(c(b(x1)))) (19)
a(a(c(b(x1)))) a(c(c(c(x1)))) (20)
b(a(c(b(x1)))) b(c(c(c(x1)))) (21)
c(a(c(b(x1)))) c(c(c(c(x1)))) (22)

1.1 Semantic Labeling

Root-labeling is applied.

We obtain the labeled TRS
aa(aa(ab(ba(x1)))) ac(cb(bc(ca(x1)))) (23)
aa(aa(ab(bb(x1)))) ac(cb(bc(cb(x1)))) (24)
aa(aa(ab(bc(x1)))) ac(cb(bc(cc(x1)))) (25)
ba(aa(ab(ba(x1)))) bc(cb(bc(ca(x1)))) (26)
ba(aa(ab(bb(x1)))) bc(cb(bc(cb(x1)))) (27)
ba(aa(ab(bc(x1)))) bc(cb(bc(cc(x1)))) (28)
ca(aa(ab(ba(x1)))) cc(cb(bc(ca(x1)))) (29)
ca(aa(ab(bb(x1)))) cc(cb(bc(cb(x1)))) (30)
ca(aa(ab(bc(x1)))) cc(cb(bc(cc(x1)))) (31)
ab(bc(cb(ba(x1)))) aa(ab(bc(ca(x1)))) (32)
ab(bc(cb(bb(x1)))) aa(ab(bc(cb(x1)))) (33)
ab(bc(cb(bc(x1)))) aa(ab(bc(cc(x1)))) (34)
bb(bc(cb(ba(x1)))) ba(ab(bc(ca(x1)))) (35)
bb(bc(cb(bb(x1)))) ba(ab(bc(cb(x1)))) (36)
bb(bc(cb(bc(x1)))) ba(ab(bc(cc(x1)))) (37)
cb(bc(cb(ba(x1)))) ca(ab(bc(ca(x1)))) (38)
cb(bc(cb(bb(x1)))) ca(ab(bc(cb(x1)))) (39)
cb(bc(cb(bc(x1)))) ca(ab(bc(cc(x1)))) (40)
aa(aa(ab(ba(x1)))) ac(ca(ab(ba(x1)))) (41)
aa(aa(ab(bb(x1)))) ac(ca(ab(bb(x1)))) (42)
aa(aa(ab(bc(x1)))) ac(ca(ab(bc(x1)))) (43)
ba(aa(ab(ba(x1)))) bc(ca(ab(ba(x1)))) (44)
ba(aa(ab(bb(x1)))) bc(ca(ab(bb(x1)))) (45)
ba(aa(ab(bc(x1)))) bc(ca(ab(bc(x1)))) (46)
ca(aa(ab(ba(x1)))) cc(ca(ab(ba(x1)))) (47)
ca(aa(ab(bb(x1)))) cc(ca(ab(bb(x1)))) (48)
ca(aa(ab(bc(x1)))) cc(ca(ab(bc(x1)))) (49)
ca(ac(ca(x1))) cb(bb(ba(x1))) (50)
ca(ac(cb(x1))) cb(bb(bb(x1))) (51)
ca(ac(cc(x1))) cb(bb(bc(x1))) (52)
cb(bc(ca(x1))) cc(cb(ba(x1))) (53)
cb(bc(cb(x1))) cc(cb(bb(x1))) (54)
cb(bc(cc(x1))) cc(cb(bc(x1))) (55)
ab(ba(ab(ba(x1)))) ac(cc(cb(ba(x1)))) (56)
ab(ba(ab(bb(x1)))) ac(cc(cb(bb(x1)))) (57)
ab(ba(ab(bc(x1)))) ac(cc(cb(bc(x1)))) (58)
bb(ba(ab(ba(x1)))) bc(cc(cb(ba(x1)))) (59)
bb(ba(ab(bb(x1)))) bc(cc(cb(bb(x1)))) (60)
bb(ba(ab(bc(x1)))) bc(cc(cb(bc(x1)))) (61)
cb(ba(ab(ba(x1)))) cc(cc(cb(ba(x1)))) (62)
cb(ba(ab(bb(x1)))) cc(cc(cb(bb(x1)))) (63)
cb(ba(ab(bc(x1)))) cc(cc(cb(bc(x1)))) (64)
aa(ac(cb(ba(x1)))) ac(cc(cc(ca(x1)))) (65)
aa(ac(cb(bb(x1)))) ac(cc(cc(cb(x1)))) (66)
aa(ac(cb(bc(x1)))) ac(cc(cc(cc(x1)))) (67)
ba(ac(cb(ba(x1)))) bc(cc(cc(ca(x1)))) (68)
ba(ac(cb(bb(x1)))) bc(cc(cc(cb(x1)))) (69)
ba(ac(cb(bc(x1)))) bc(cc(cc(cc(x1)))) (70)
ca(ac(cb(ba(x1)))) cc(cc(cc(ca(x1)))) (71)
ca(ac(cb(bb(x1)))) cc(cc(cc(cb(x1)))) (72)
ca(ac(cb(bc(x1)))) cc(cc(cc(cc(x1)))) (73)

1.1.1 Rule Removal

Using the Knuth Bendix order with w0 = 1 and the following precedence and weight functions
prec(aa) = 4 weight(aa) = 5
prec(ab) = 6 weight(ab) = 2
prec(ba) = 0 weight(ba) = 7
prec(ac) = 3 weight(ac) = 4
prec(cb) = 5 weight(cb) = 4
prec(bc) = 1 weight(bc) = 2
prec(ca) = 8 weight(ca) = 6
prec(bb) = 7 weight(bb) = 5
prec(cc) = 2 weight(cc) = 1
all of the following rules can be deleted.
aa(aa(ab(ba(x1)))) ac(cb(bc(ca(x1)))) (23)
aa(aa(ab(bb(x1)))) ac(cb(bc(cb(x1)))) (24)
aa(aa(ab(bc(x1)))) ac(cb(bc(cc(x1)))) (25)
ba(aa(ab(ba(x1)))) bc(cb(bc(ca(x1)))) (26)
ba(aa(ab(bb(x1)))) bc(cb(bc(cb(x1)))) (27)
ba(aa(ab(bc(x1)))) bc(cb(bc(cc(x1)))) (28)
ca(aa(ab(ba(x1)))) cc(cb(bc(ca(x1)))) (29)
ca(aa(ab(bb(x1)))) cc(cb(bc(cb(x1)))) (30)
ca(aa(ab(bc(x1)))) cc(cb(bc(cc(x1)))) (31)
ab(bc(cb(ba(x1)))) aa(ab(bc(ca(x1)))) (32)
ab(bc(cb(bb(x1)))) aa(ab(bc(cb(x1)))) (33)
ab(bc(cb(bc(x1)))) aa(ab(bc(cc(x1)))) (34)
bb(bc(cb(ba(x1)))) ba(ab(bc(ca(x1)))) (35)
bb(bc(cb(bb(x1)))) ba(ab(bc(cb(x1)))) (36)
bb(bc(cb(bc(x1)))) ba(ab(bc(cc(x1)))) (37)
cb(bc(cb(ba(x1)))) ca(ab(bc(ca(x1)))) (38)
cb(bc(cb(bb(x1)))) ca(ab(bc(cb(x1)))) (39)
cb(bc(cb(bc(x1)))) ca(ab(bc(cc(x1)))) (40)
aa(aa(ab(ba(x1)))) ac(ca(ab(ba(x1)))) (41)
aa(aa(ab(bb(x1)))) ac(ca(ab(bb(x1)))) (42)
aa(aa(ab(bc(x1)))) ac(ca(ab(bc(x1)))) (43)
ba(aa(ab(ba(x1)))) bc(ca(ab(ba(x1)))) (44)
ba(aa(ab(bb(x1)))) bc(ca(ab(bb(x1)))) (45)
ba(aa(ab(bc(x1)))) bc(ca(ab(bc(x1)))) (46)
ca(aa(ab(ba(x1)))) cc(ca(ab(ba(x1)))) (47)
ca(aa(ab(bb(x1)))) cc(ca(ab(bb(x1)))) (48)
ca(aa(ab(bc(x1)))) cc(ca(ab(bc(x1)))) (49)
ca(ac(ca(x1))) cb(bb(ba(x1))) (50)
ca(ac(cb(x1))) cb(bb(bb(x1))) (51)
ca(ac(cc(x1))) cb(bb(bc(x1))) (52)
cb(bc(ca(x1))) cc(cb(ba(x1))) (53)
cb(bc(cb(x1))) cc(cb(bb(x1))) (54)
cb(bc(cc(x1))) cc(cb(bc(x1))) (55)
ab(ba(ab(ba(x1)))) ac(cc(cb(ba(x1)))) (56)
ab(ba(ab(bb(x1)))) ac(cc(cb(bb(x1)))) (57)
ab(ba(ab(bc(x1)))) ac(cc(cb(bc(x1)))) (58)
bb(ba(ab(ba(x1)))) bc(cc(cb(ba(x1)))) (59)
bb(ba(ab(bb(x1)))) bc(cc(cb(bb(x1)))) (60)
bb(ba(ab(bc(x1)))) bc(cc(cb(bc(x1)))) (61)
cb(ba(ab(ba(x1)))) cc(cc(cb(ba(x1)))) (62)
cb(ba(ab(bb(x1)))) cc(cc(cb(bb(x1)))) (63)
cb(ba(ab(bc(x1)))) cc(cc(cb(bc(x1)))) (64)
aa(ac(cb(ba(x1)))) ac(cc(cc(ca(x1)))) (65)
aa(ac(cb(bb(x1)))) ac(cc(cc(cb(x1)))) (66)
aa(ac(cb(bc(x1)))) ac(cc(cc(cc(x1)))) (67)
ba(ac(cb(ba(x1)))) bc(cc(cc(ca(x1)))) (68)
ba(ac(cb(bb(x1)))) bc(cc(cc(cb(x1)))) (69)
ba(ac(cb(bc(x1)))) bc(cc(cc(cc(x1)))) (70)
ca(ac(cb(ba(x1)))) cc(cc(cc(ca(x1)))) (71)
ca(ac(cb(bb(x1)))) cc(cc(cc(cb(x1)))) (72)
ca(ac(cb(bc(x1)))) cc(cc(cc(cc(x1)))) (73)

1.1.1.1 R is empty

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