(0) Obligation:

Clauses:

fold(X, [], X).
fold(X, Y, Z) :- ','(no(empty(Y)), ','(head(Y, H), ','(tail(Y, T), ','(myop(X, H, V), fold(V, T, Z))))).
myop(a, b, c).
head([], X1).
head(.(H, X2), H).
tail([], []).
tail(.(X3, T), T).
empty([]).
no(X) :- ','(X, ','(!, failure(a))).
no(X4).
failure(b).

Query: fold(g,g,a)

(1) PrologToPiTRSViaGraphTransformerProof (SOUND transformation)

Transformed Prolog program to (Pi-)TRS.

(2) Obligation:

Pi-finite rewrite system:
The TRS R consists of the following rules:

foldA_in_gga(T5, [], T5) → foldA_out_gga(T5, [], T5)
foldA_in_gga(a, .(b, []), c) → foldA_out_gga(a, .(b, []), c)

The argument filtering Pi contains the following mapping:
foldA_in_gga(x1, x2, x3)  =  foldA_in_gga(x1, x2)
[]  =  []
foldA_out_gga(x1, x2, x3)  =  foldA_out_gga(x1, x2, x3)
a  =  a
.(x1, x2)  =  .(x1, x2)
b  =  b

(3) DependencyPairsProof (EQUIVALENT transformation)

Using Dependency Pairs [AG00,LOPSTR] we result in the following initial DP problem:
Pi DP problem:
P is empty.
The TRS R consists of the following rules:

foldA_in_gga(T5, [], T5) → foldA_out_gga(T5, [], T5)
foldA_in_gga(a, .(b, []), c) → foldA_out_gga(a, .(b, []), c)

The argument filtering Pi contains the following mapping:
foldA_in_gga(x1, x2, x3)  =  foldA_in_gga(x1, x2)
[]  =  []
foldA_out_gga(x1, x2, x3)  =  foldA_out_gga(x1, x2, x3)
a  =  a
.(x1, x2)  =  .(x1, x2)
b  =  b

We have to consider all (P,R,Pi)-chains

(4) Obligation:

Pi DP problem:
P is empty.
The TRS R consists of the following rules:

foldA_in_gga(T5, [], T5) → foldA_out_gga(T5, [], T5)
foldA_in_gga(a, .(b, []), c) → foldA_out_gga(a, .(b, []), c)

The argument filtering Pi contains the following mapping:
foldA_in_gga(x1, x2, x3)  =  foldA_in_gga(x1, x2)
[]  =  []
foldA_out_gga(x1, x2, x3)  =  foldA_out_gga(x1, x2, x3)
a  =  a
.(x1, x2)  =  .(x1, x2)
b  =  b

We have to consider all (P,R,Pi)-chains

(5) PisEmptyProof (EQUIVALENT transformation)

The TRS P is empty. Hence, there is no (P,R,Pi) chain.

(6) YES