Certification Problem

Input (TPDB SRS_Relative/Waldmann_19/random-168)

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

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

and S is the following TRS.

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

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

We obtain the transformed TRS
a(c(c(x1))) a(c(b(x1))) (2)
a(b(b(x1))) a(a(b(x1))) (3)
c(c(a(a(x1)))) c(a(c(a(x1)))) (8)
a(c(a(a(x1)))) a(a(c(a(x1)))) (9)
b(c(a(a(x1)))) b(a(c(a(x1)))) (10)
a(b(b(x1))) a(b(c(x1))) (7)
c(a(a(b(x1)))) c(c(a(b(x1)))) (11)
a(a(a(b(x1)))) a(c(a(b(x1)))) (12)
b(a(a(b(x1)))) b(c(a(b(x1)))) (13)
c(a(c(c(x1)))) c(c(a(b(x1)))) (14)
a(a(c(c(x1)))) a(c(a(b(x1)))) (15)
b(a(c(c(x1)))) b(c(a(b(x1)))) (16)
c(a(a(a(x1)))) c(c(b(a(x1)))) (17)
a(a(a(a(x1)))) a(c(b(a(x1)))) (18)
b(a(a(a(x1)))) b(c(b(a(x1)))) (19)

1.1 Semantic Labeling

Root-labeling is applied.

We obtain the labeled TRS
ac(cc(ca(x1))) ac(cb(ba(x1))) (20)
ac(cc(cc(x1))) ac(cb(bc(x1))) (21)
ac(cc(cb(x1))) ac(cb(bb(x1))) (22)
ab(bb(ba(x1))) aa(ab(ba(x1))) (23)
ab(bb(bc(x1))) aa(ab(bc(x1))) (24)
ab(bb(bb(x1))) aa(ab(bb(x1))) (25)
cc(ca(aa(aa(x1)))) ca(ac(ca(aa(x1)))) (26)
cc(ca(aa(ac(x1)))) ca(ac(ca(ac(x1)))) (27)
cc(ca(aa(ab(x1)))) ca(ac(ca(ab(x1)))) (28)
ac(ca(aa(aa(x1)))) aa(ac(ca(aa(x1)))) (29)
ac(ca(aa(ac(x1)))) aa(ac(ca(ac(x1)))) (30)
ac(ca(aa(ab(x1)))) aa(ac(ca(ab(x1)))) (31)
bc(ca(aa(aa(x1)))) ba(ac(ca(aa(x1)))) (32)
bc(ca(aa(ac(x1)))) ba(ac(ca(ac(x1)))) (33)
bc(ca(aa(ab(x1)))) ba(ac(ca(ab(x1)))) (34)
ab(bb(ba(x1))) ab(bc(ca(x1))) (35)
ab(bb(bc(x1))) ab(bc(cc(x1))) (36)
ab(bb(bb(x1))) ab(bc(cb(x1))) (37)
ca(aa(ab(ba(x1)))) cc(ca(ab(ba(x1)))) (38)
ca(aa(ab(bc(x1)))) cc(ca(ab(bc(x1)))) (39)
ca(aa(ab(bb(x1)))) cc(ca(ab(bb(x1)))) (40)
aa(aa(ab(ba(x1)))) ac(ca(ab(ba(x1)))) (41)
aa(aa(ab(bc(x1)))) ac(ca(ab(bc(x1)))) (42)
aa(aa(ab(bb(x1)))) ac(ca(ab(bb(x1)))) (43)
ba(aa(ab(ba(x1)))) bc(ca(ab(ba(x1)))) (44)
ba(aa(ab(bc(x1)))) bc(ca(ab(bc(x1)))) (45)
ba(aa(ab(bb(x1)))) bc(ca(ab(bb(x1)))) (46)
ca(ac(cc(ca(x1)))) cc(ca(ab(ba(x1)))) (47)
ca(ac(cc(cc(x1)))) cc(ca(ab(bc(x1)))) (48)
ca(ac(cc(cb(x1)))) cc(ca(ab(bb(x1)))) (49)
aa(ac(cc(ca(x1)))) ac(ca(ab(ba(x1)))) (50)
aa(ac(cc(cc(x1)))) ac(ca(ab(bc(x1)))) (51)
aa(ac(cc(cb(x1)))) ac(ca(ab(bb(x1)))) (52)
ba(ac(cc(ca(x1)))) bc(ca(ab(ba(x1)))) (53)
ba(ac(cc(cc(x1)))) bc(ca(ab(bc(x1)))) (54)
ba(ac(cc(cb(x1)))) bc(ca(ab(bb(x1)))) (55)
ca(aa(aa(aa(x1)))) cc(cb(ba(aa(x1)))) (56)
ca(aa(aa(ac(x1)))) cc(cb(ba(ac(x1)))) (57)
ca(aa(aa(ab(x1)))) cc(cb(ba(ab(x1)))) (58)
aa(aa(aa(aa(x1)))) ac(cb(ba(aa(x1)))) (59)
aa(aa(aa(ac(x1)))) ac(cb(ba(ac(x1)))) (60)
aa(aa(aa(ab(x1)))) ac(cb(ba(ab(x1)))) (61)
ba(aa(aa(aa(x1)))) bc(cb(ba(aa(x1)))) (62)
ba(aa(aa(ac(x1)))) bc(cb(ba(ac(x1)))) (63)
ba(aa(aa(ab(x1)))) bc(cb(ba(ab(x1)))) (64)

1.1.1 Rule Removal

Using the Knuth Bendix order with w0 = 1 and the following precedence and weight functions
prec(ac) = 3 weight(ac) = 5
prec(cc) = 6 weight(cc) = 11
prec(ca) = 7 weight(ca) = 15
prec(cb) = 4 weight(cb) = 8
prec(ba) = 0 weight(ba) = 17
prec(bc) = 5 weight(bc) = 12
prec(bb) = 8 weight(bb) = 11
prec(ab) = 2 weight(ab) = 1
prec(aa) = 1 weight(aa) = 11
all of the following rules can be deleted.
ac(cc(ca(x1))) ac(cb(ba(x1))) (20)
ac(cc(cc(x1))) ac(cb(bc(x1))) (21)
ac(cc(cb(x1))) ac(cb(bb(x1))) (22)
ab(bb(ba(x1))) aa(ab(ba(x1))) (23)
ab(bb(bc(x1))) aa(ab(bc(x1))) (24)
ab(bb(bb(x1))) aa(ab(bb(x1))) (25)
cc(ca(aa(aa(x1)))) ca(ac(ca(aa(x1)))) (26)
cc(ca(aa(ac(x1)))) ca(ac(ca(ac(x1)))) (27)
cc(ca(aa(ab(x1)))) ca(ac(ca(ab(x1)))) (28)
ac(ca(aa(aa(x1)))) aa(ac(ca(aa(x1)))) (29)
ac(ca(aa(ac(x1)))) aa(ac(ca(ac(x1)))) (30)
ac(ca(aa(ab(x1)))) aa(ac(ca(ab(x1)))) (31)
bc(ca(aa(aa(x1)))) ba(ac(ca(aa(x1)))) (32)
bc(ca(aa(ac(x1)))) ba(ac(ca(ac(x1)))) (33)
bc(ca(aa(ab(x1)))) ba(ac(ca(ab(x1)))) (34)
ab(bb(ba(x1))) ab(bc(ca(x1))) (35)
ab(bb(bc(x1))) ab(bc(cc(x1))) (36)
ab(bb(bb(x1))) ab(bc(cb(x1))) (37)
ca(aa(ab(ba(x1)))) cc(ca(ab(ba(x1)))) (38)
ca(aa(ab(bc(x1)))) cc(ca(ab(bc(x1)))) (39)
ca(aa(ab(bb(x1)))) cc(ca(ab(bb(x1)))) (40)
aa(aa(ab(ba(x1)))) ac(ca(ab(ba(x1)))) (41)
aa(aa(ab(bc(x1)))) ac(ca(ab(bc(x1)))) (42)
aa(aa(ab(bb(x1)))) ac(ca(ab(bb(x1)))) (43)
ba(aa(ab(ba(x1)))) bc(ca(ab(ba(x1)))) (44)
ba(aa(ab(bc(x1)))) bc(ca(ab(bc(x1)))) (45)
ba(aa(ab(bb(x1)))) bc(ca(ab(bb(x1)))) (46)
ca(ac(cc(ca(x1)))) cc(ca(ab(ba(x1)))) (47)
ca(ac(cc(cc(x1)))) cc(ca(ab(bc(x1)))) (48)
ca(ac(cc(cb(x1)))) cc(ca(ab(bb(x1)))) (49)
aa(ac(cc(ca(x1)))) ac(ca(ab(ba(x1)))) (50)
aa(ac(cc(cc(x1)))) ac(ca(ab(bc(x1)))) (51)
aa(ac(cc(cb(x1)))) ac(ca(ab(bb(x1)))) (52)
ba(ac(cc(ca(x1)))) bc(ca(ab(ba(x1)))) (53)
ba(ac(cc(cc(x1)))) bc(ca(ab(bc(x1)))) (54)
ba(ac(cc(cb(x1)))) bc(ca(ab(bb(x1)))) (55)
ca(aa(aa(aa(x1)))) cc(cb(ba(aa(x1)))) (56)
ca(aa(aa(ac(x1)))) cc(cb(ba(ac(x1)))) (57)
ca(aa(aa(ab(x1)))) cc(cb(ba(ab(x1)))) (58)
aa(aa(aa(aa(x1)))) ac(cb(ba(aa(x1)))) (59)
aa(aa(aa(ac(x1)))) ac(cb(ba(ac(x1)))) (60)
aa(aa(aa(ab(x1)))) ac(cb(ba(ab(x1)))) (61)
ba(aa(aa(aa(x1)))) bc(cb(ba(aa(x1)))) (62)
ba(aa(aa(ac(x1)))) bc(cb(ba(ac(x1)))) (63)
ba(aa(aa(ab(x1)))) bc(cb(ba(ab(x1)))) (64)

1.1.1.1 R is empty

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