Certification Problem

Input (TPDB SRS_Relative/Waldmann_19/random-77)

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

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

and S is the following TRS.

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

Property / Task

Prove or disprove termination.

Answer / Result

Yes.

Proof (by AProVE @ termCOMP 2023)

1 String Reversal

Since only unary symbols occur, one can reverse all terms and obtains the TRS
c(b(b(x1))) c(a(c(x1))) (8)
b(c(a(x1))) c(c(b(x1))) (9)
b(b(b(x1))) a(c(b(x1))) (10)
b(a(c(x1))) a(b(b(x1))) (11)
b(a(a(x1))) a(a(b(x1))) (12)
a(a(b(x1))) b(c(c(x1))) (13)
a(a(b(x1))) c(c(c(x1))) (14)

1.1 Closure Under Flat Contexts

Using the flat contexts

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

We obtain the transformed TRS
c(b(b(x1))) c(a(c(x1))) (8)
c(b(c(a(x1)))) c(c(c(b(x1)))) (15)
b(b(c(a(x1)))) b(c(c(b(x1)))) (16)
a(b(c(a(x1)))) a(c(c(b(x1)))) (17)
c(b(b(b(x1)))) c(a(c(b(x1)))) (18)
b(b(b(b(x1)))) b(a(c(b(x1)))) (19)
a(b(b(b(x1)))) a(a(c(b(x1)))) (20)
c(b(a(c(x1)))) c(a(b(b(x1)))) (21)
b(b(a(c(x1)))) b(a(b(b(x1)))) (22)
a(b(a(c(x1)))) a(a(b(b(x1)))) (23)
c(b(a(a(x1)))) c(a(a(b(x1)))) (24)
b(b(a(a(x1)))) b(a(a(b(x1)))) (25)
a(b(a(a(x1)))) a(a(a(b(x1)))) (26)
c(a(a(b(x1)))) c(b(c(c(x1)))) (27)
b(a(a(b(x1)))) b(b(c(c(x1)))) (28)
a(a(a(b(x1)))) a(b(c(c(x1)))) (29)
c(a(a(b(x1)))) c(c(c(c(x1)))) (30)
b(a(a(b(x1)))) b(c(c(c(x1)))) (31)
a(a(a(b(x1)))) a(c(c(c(x1)))) (32)

1.1.1 Semantic Labeling

Root-labeling is applied.

We obtain the labeled TRS
cb(bb(bc(x1))) ca(ac(cc(x1))) (33)
cb(bb(bb(x1))) ca(ac(cb(x1))) (34)
cb(bb(ba(x1))) ca(ac(ca(x1))) (35)
cb(bc(ca(ac(x1)))) cc(cc(cb(bc(x1)))) (36)
cb(bc(ca(ab(x1)))) cc(cc(cb(bb(x1)))) (37)
cb(bc(ca(aa(x1)))) cc(cc(cb(ba(x1)))) (38)
bb(bc(ca(ac(x1)))) bc(cc(cb(bc(x1)))) (39)
bb(bc(ca(ab(x1)))) bc(cc(cb(bb(x1)))) (40)
bb(bc(ca(aa(x1)))) bc(cc(cb(ba(x1)))) (41)
ab(bc(ca(ac(x1)))) ac(cc(cb(bc(x1)))) (42)
ab(bc(ca(ab(x1)))) ac(cc(cb(bb(x1)))) (43)
ab(bc(ca(aa(x1)))) ac(cc(cb(ba(x1)))) (44)
cb(bb(bb(bc(x1)))) ca(ac(cb(bc(x1)))) (45)
cb(bb(bb(bb(x1)))) ca(ac(cb(bb(x1)))) (46)
cb(bb(bb(ba(x1)))) ca(ac(cb(ba(x1)))) (47)
bb(bb(bb(bc(x1)))) ba(ac(cb(bc(x1)))) (48)
bb(bb(bb(bb(x1)))) ba(ac(cb(bb(x1)))) (49)
bb(bb(bb(ba(x1)))) ba(ac(cb(ba(x1)))) (50)
ab(bb(bb(bc(x1)))) aa(ac(cb(bc(x1)))) (51)
ab(bb(bb(bb(x1)))) aa(ac(cb(bb(x1)))) (52)
ab(bb(bb(ba(x1)))) aa(ac(cb(ba(x1)))) (53)
cb(ba(ac(cc(x1)))) ca(ab(bb(bc(x1)))) (54)
cb(ba(ac(cb(x1)))) ca(ab(bb(bb(x1)))) (55)
cb(ba(ac(ca(x1)))) ca(ab(bb(ba(x1)))) (56)
bb(ba(ac(cc(x1)))) ba(ab(bb(bc(x1)))) (57)
bb(ba(ac(cb(x1)))) ba(ab(bb(bb(x1)))) (58)
bb(ba(ac(ca(x1)))) ba(ab(bb(ba(x1)))) (59)
ab(ba(ac(cc(x1)))) aa(ab(bb(bc(x1)))) (60)
ab(ba(ac(cb(x1)))) aa(ab(bb(bb(x1)))) (61)
ab(ba(ac(ca(x1)))) aa(ab(bb(ba(x1)))) (62)
cb(ba(aa(ac(x1)))) ca(aa(ab(bc(x1)))) (63)
cb(ba(aa(ab(x1)))) ca(aa(ab(bb(x1)))) (64)
cb(ba(aa(aa(x1)))) ca(aa(ab(ba(x1)))) (65)
bb(ba(aa(ac(x1)))) ba(aa(ab(bc(x1)))) (66)
bb(ba(aa(ab(x1)))) ba(aa(ab(bb(x1)))) (67)
bb(ba(aa(aa(x1)))) ba(aa(ab(ba(x1)))) (68)
ab(ba(aa(ac(x1)))) aa(aa(ab(bc(x1)))) (69)
ab(ba(aa(ab(x1)))) aa(aa(ab(bb(x1)))) (70)
ab(ba(aa(aa(x1)))) aa(aa(ab(ba(x1)))) (71)
ca(aa(ab(bc(x1)))) cb(bc(cc(cc(x1)))) (72)
ca(aa(ab(bb(x1)))) cb(bc(cc(cb(x1)))) (73)
ca(aa(ab(ba(x1)))) cb(bc(cc(ca(x1)))) (74)
ba(aa(ab(bc(x1)))) bb(bc(cc(cc(x1)))) (75)
ba(aa(ab(bb(x1)))) bb(bc(cc(cb(x1)))) (76)
ba(aa(ab(ba(x1)))) bb(bc(cc(ca(x1)))) (77)
aa(aa(ab(bc(x1)))) ab(bc(cc(cc(x1)))) (78)
aa(aa(ab(bb(x1)))) ab(bc(cc(cb(x1)))) (79)
aa(aa(ab(ba(x1)))) ab(bc(cc(ca(x1)))) (80)
ca(aa(ab(bc(x1)))) cc(cc(cc(cc(x1)))) (81)
ca(aa(ab(bb(x1)))) cc(cc(cc(cb(x1)))) (82)
ca(aa(ab(ba(x1)))) cc(cc(cc(ca(x1)))) (83)
ba(aa(ab(bc(x1)))) bc(cc(cc(cc(x1)))) (84)
ba(aa(ab(bb(x1)))) bc(cc(cc(cb(x1)))) (85)
ba(aa(ab(ba(x1)))) bc(cc(cc(ca(x1)))) (86)
aa(aa(ab(bc(x1)))) ac(cc(cc(cc(x1)))) (87)
aa(aa(ab(bb(x1)))) ac(cc(cc(cb(x1)))) (88)
aa(aa(ab(ba(x1)))) ac(cc(cc(ca(x1)))) (89)

1.1.1.1 Rule Removal

Using the Knuth Bendix order with w0 = 1 and the following precedence and weight functions
prec(cb) = 2 weight(cb) = 8
prec(bb) = 7 weight(bb) = 6
prec(bc) = 1 weight(bc) = 3
prec(ca) = 0 weight(ca) = 11
prec(ac) = 3 weight(ac) = 1
prec(cc) = 5 weight(cc) = 5
prec(ba) = 4 weight(ba) = 9
prec(ab) = 8 weight(ab) = 3
prec(aa) = 6 weight(aa) = 6
all of the following rules can be deleted.
cb(bb(bc(x1))) ca(ac(cc(x1))) (33)
cb(bb(bb(x1))) ca(ac(cb(x1))) (34)
cb(bb(ba(x1))) ca(ac(ca(x1))) (35)
cb(bc(ca(ac(x1)))) cc(cc(cb(bc(x1)))) (36)
cb(bc(ca(ab(x1)))) cc(cc(cb(bb(x1)))) (37)
cb(bc(ca(aa(x1)))) cc(cc(cb(ba(x1)))) (38)
bb(bc(ca(ac(x1)))) bc(cc(cb(bc(x1)))) (39)
bb(bc(ca(ab(x1)))) bc(cc(cb(bb(x1)))) (40)
bb(bc(ca(aa(x1)))) bc(cc(cb(ba(x1)))) (41)
ab(bc(ca(ac(x1)))) ac(cc(cb(bc(x1)))) (42)
ab(bc(ca(ab(x1)))) ac(cc(cb(bb(x1)))) (43)
ab(bc(ca(aa(x1)))) ac(cc(cb(ba(x1)))) (44)
cb(bb(bb(bc(x1)))) ca(ac(cb(bc(x1)))) (45)
cb(bb(bb(bb(x1)))) ca(ac(cb(bb(x1)))) (46)
cb(bb(bb(ba(x1)))) ca(ac(cb(ba(x1)))) (47)
bb(bb(bb(bc(x1)))) ba(ac(cb(bc(x1)))) (48)
bb(bb(bb(bb(x1)))) ba(ac(cb(bb(x1)))) (49)
bb(bb(bb(ba(x1)))) ba(ac(cb(ba(x1)))) (50)
ab(bb(bb(bc(x1)))) aa(ac(cb(bc(x1)))) (51)
ab(bb(bb(bb(x1)))) aa(ac(cb(bb(x1)))) (52)
ab(bb(bb(ba(x1)))) aa(ac(cb(ba(x1)))) (53)
cb(ba(ac(cc(x1)))) ca(ab(bb(bc(x1)))) (54)
cb(ba(ac(cb(x1)))) ca(ab(bb(bb(x1)))) (55)
cb(ba(ac(ca(x1)))) ca(ab(bb(ba(x1)))) (56)
bb(ba(ac(cc(x1)))) ba(ab(bb(bc(x1)))) (57)
bb(ba(ac(cb(x1)))) ba(ab(bb(bb(x1)))) (58)
bb(ba(ac(ca(x1)))) ba(ab(bb(ba(x1)))) (59)
ab(ba(ac(cc(x1)))) aa(ab(bb(bc(x1)))) (60)
ab(ba(ac(cb(x1)))) aa(ab(bb(bb(x1)))) (61)
ab(ba(ac(ca(x1)))) aa(ab(bb(ba(x1)))) (62)
cb(ba(aa(ac(x1)))) ca(aa(ab(bc(x1)))) (63)
cb(ba(aa(ab(x1)))) ca(aa(ab(bb(x1)))) (64)
cb(ba(aa(aa(x1)))) ca(aa(ab(ba(x1)))) (65)
bb(ba(aa(ac(x1)))) ba(aa(ab(bc(x1)))) (66)
bb(ba(aa(ab(x1)))) ba(aa(ab(bb(x1)))) (67)
bb(ba(aa(aa(x1)))) ba(aa(ab(ba(x1)))) (68)
ab(ba(aa(ac(x1)))) aa(aa(ab(bc(x1)))) (69)
ab(ba(aa(ab(x1)))) aa(aa(ab(bb(x1)))) (70)
ab(ba(aa(aa(x1)))) aa(aa(ab(ba(x1)))) (71)
ca(aa(ab(bc(x1)))) cb(bc(cc(cc(x1)))) (72)
ca(aa(ab(bb(x1)))) cb(bc(cc(cb(x1)))) (73)
ca(aa(ab(ba(x1)))) cb(bc(cc(ca(x1)))) (74)
ba(aa(ab(bc(x1)))) bb(bc(cc(cc(x1)))) (75)
ba(aa(ab(bb(x1)))) bb(bc(cc(cb(x1)))) (76)
ba(aa(ab(ba(x1)))) bb(bc(cc(ca(x1)))) (77)
aa(aa(ab(bc(x1)))) ab(bc(cc(cc(x1)))) (78)
aa(aa(ab(bb(x1)))) ab(bc(cc(cb(x1)))) (79)
aa(aa(ab(ba(x1)))) ab(bc(cc(ca(x1)))) (80)
ca(aa(ab(bc(x1)))) cc(cc(cc(cc(x1)))) (81)
ca(aa(ab(bb(x1)))) cc(cc(cc(cb(x1)))) (82)
ca(aa(ab(ba(x1)))) cc(cc(cc(ca(x1)))) (83)
ba(aa(ab(bc(x1)))) bc(cc(cc(cc(x1)))) (84)
ba(aa(ab(bb(x1)))) bc(cc(cc(cb(x1)))) (85)
ba(aa(ab(ba(x1)))) bc(cc(cc(ca(x1)))) (86)
aa(aa(ab(bc(x1)))) ac(cc(cc(cc(x1)))) (87)
aa(aa(ab(bb(x1)))) ac(cc(cc(cb(x1)))) (88)
aa(aa(ab(ba(x1)))) ac(cc(cc(ca(x1)))) (89)

1.1.1.1.1 R is empty

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