Left Termination of the query pattern mult_in_3(g, g, a) w.r.t. the given Prolog program could successfully be proven:



Prolog
  ↳ PrologToPiTRSProof

Clauses:

mult(X, 0, 0).
mult(X, s(Y), Z) :- ','(mult(X, Y, W), sum(W, X, Z)).
sum(X, 0, X).
sum(X, s(Y), s(Z)) :- sum(X, Y, Z).

Queries:

mult(g,g,a).

We use the technique of [30]. With regard to the inferred argument filtering the predicates were used in the following modes:
mult_in: (b,b,f)
sum_in: (b,b,f)
Transforming Prolog into the following Term Rewriting System:
Pi-finite rewrite system:
The TRS R consists of the following rules:

mult_in_gga(X, 0, 0) → mult_out_gga(X, 0, 0)
mult_in_gga(X, s(Y), Z) → U1_gga(X, Y, Z, mult_in_gga(X, Y, W))
U1_gga(X, Y, Z, mult_out_gga(X, Y, W)) → U2_gga(X, Y, Z, sum_in_gga(W, X, Z))
sum_in_gga(X, 0, X) → sum_out_gga(X, 0, X)
sum_in_gga(X, s(Y), s(Z)) → U3_gga(X, Y, Z, sum_in_gga(X, Y, Z))
U3_gga(X, Y, Z, sum_out_gga(X, Y, Z)) → sum_out_gga(X, s(Y), s(Z))
U2_gga(X, Y, Z, sum_out_gga(W, X, Z)) → mult_out_gga(X, s(Y), Z)

The argument filtering Pi contains the following mapping:
mult_in_gga(x1, x2, x3)  =  mult_in_gga(x1, x2)
0  =  0
mult_out_gga(x1, x2, x3)  =  mult_out_gga(x3)
s(x1)  =  s(x1)
U1_gga(x1, x2, x3, x4)  =  U1_gga(x1, x4)
U2_gga(x1, x2, x3, x4)  =  U2_gga(x4)
sum_in_gga(x1, x2, x3)  =  sum_in_gga(x1, x2)
sum_out_gga(x1, x2, x3)  =  sum_out_gga(x3)
U3_gga(x1, x2, x3, x4)  =  U3_gga(x4)

Infinitary Constructor Rewriting Termination of PiTRS implies Termination of Prolog



↳ Prolog
  ↳ PrologToPiTRSProof
PiTRS
      ↳ DependencyPairsProof

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

mult_in_gga(X, 0, 0) → mult_out_gga(X, 0, 0)
mult_in_gga(X, s(Y), Z) → U1_gga(X, Y, Z, mult_in_gga(X, Y, W))
U1_gga(X, Y, Z, mult_out_gga(X, Y, W)) → U2_gga(X, Y, Z, sum_in_gga(W, X, Z))
sum_in_gga(X, 0, X) → sum_out_gga(X, 0, X)
sum_in_gga(X, s(Y), s(Z)) → U3_gga(X, Y, Z, sum_in_gga(X, Y, Z))
U3_gga(X, Y, Z, sum_out_gga(X, Y, Z)) → sum_out_gga(X, s(Y), s(Z))
U2_gga(X, Y, Z, sum_out_gga(W, X, Z)) → mult_out_gga(X, s(Y), Z)

The argument filtering Pi contains the following mapping:
mult_in_gga(x1, x2, x3)  =  mult_in_gga(x1, x2)
0  =  0
mult_out_gga(x1, x2, x3)  =  mult_out_gga(x3)
s(x1)  =  s(x1)
U1_gga(x1, x2, x3, x4)  =  U1_gga(x1, x4)
U2_gga(x1, x2, x3, x4)  =  U2_gga(x4)
sum_in_gga(x1, x2, x3)  =  sum_in_gga(x1, x2)
sum_out_gga(x1, x2, x3)  =  sum_out_gga(x3)
U3_gga(x1, x2, x3, x4)  =  U3_gga(x4)


Using Dependency Pairs [1,30] we result in the following initial DP problem:
Pi DP problem:
The TRS P consists of the following rules:

MULT_IN_GGA(X, s(Y), Z) → U1_GGA(X, Y, Z, mult_in_gga(X, Y, W))
MULT_IN_GGA(X, s(Y), Z) → MULT_IN_GGA(X, Y, W)
U1_GGA(X, Y, Z, mult_out_gga(X, Y, W)) → U2_GGA(X, Y, Z, sum_in_gga(W, X, Z))
U1_GGA(X, Y, Z, mult_out_gga(X, Y, W)) → SUM_IN_GGA(W, X, Z)
SUM_IN_GGA(X, s(Y), s(Z)) → U3_GGA(X, Y, Z, sum_in_gga(X, Y, Z))
SUM_IN_GGA(X, s(Y), s(Z)) → SUM_IN_GGA(X, Y, Z)

The TRS R consists of the following rules:

mult_in_gga(X, 0, 0) → mult_out_gga(X, 0, 0)
mult_in_gga(X, s(Y), Z) → U1_gga(X, Y, Z, mult_in_gga(X, Y, W))
U1_gga(X, Y, Z, mult_out_gga(X, Y, W)) → U2_gga(X, Y, Z, sum_in_gga(W, X, Z))
sum_in_gga(X, 0, X) → sum_out_gga(X, 0, X)
sum_in_gga(X, s(Y), s(Z)) → U3_gga(X, Y, Z, sum_in_gga(X, Y, Z))
U3_gga(X, Y, Z, sum_out_gga(X, Y, Z)) → sum_out_gga(X, s(Y), s(Z))
U2_gga(X, Y, Z, sum_out_gga(W, X, Z)) → mult_out_gga(X, s(Y), Z)

The argument filtering Pi contains the following mapping:
mult_in_gga(x1, x2, x3)  =  mult_in_gga(x1, x2)
0  =  0
mult_out_gga(x1, x2, x3)  =  mult_out_gga(x3)
s(x1)  =  s(x1)
U1_gga(x1, x2, x3, x4)  =  U1_gga(x1, x4)
U2_gga(x1, x2, x3, x4)  =  U2_gga(x4)
sum_in_gga(x1, x2, x3)  =  sum_in_gga(x1, x2)
sum_out_gga(x1, x2, x3)  =  sum_out_gga(x3)
U3_gga(x1, x2, x3, x4)  =  U3_gga(x4)
U2_GGA(x1, x2, x3, x4)  =  U2_GGA(x4)
SUM_IN_GGA(x1, x2, x3)  =  SUM_IN_GGA(x1, x2)
MULT_IN_GGA(x1, x2, x3)  =  MULT_IN_GGA(x1, x2)
U1_GGA(x1, x2, x3, x4)  =  U1_GGA(x1, x4)
U3_GGA(x1, x2, x3, x4)  =  U3_GGA(x4)

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

↳ Prolog
  ↳ PrologToPiTRSProof
    ↳ PiTRS
      ↳ DependencyPairsProof
PiDP
          ↳ DependencyGraphProof

Pi DP problem:
The TRS P consists of the following rules:

MULT_IN_GGA(X, s(Y), Z) → U1_GGA(X, Y, Z, mult_in_gga(X, Y, W))
MULT_IN_GGA(X, s(Y), Z) → MULT_IN_GGA(X, Y, W)
U1_GGA(X, Y, Z, mult_out_gga(X, Y, W)) → U2_GGA(X, Y, Z, sum_in_gga(W, X, Z))
U1_GGA(X, Y, Z, mult_out_gga(X, Y, W)) → SUM_IN_GGA(W, X, Z)
SUM_IN_GGA(X, s(Y), s(Z)) → U3_GGA(X, Y, Z, sum_in_gga(X, Y, Z))
SUM_IN_GGA(X, s(Y), s(Z)) → SUM_IN_GGA(X, Y, Z)

The TRS R consists of the following rules:

mult_in_gga(X, 0, 0) → mult_out_gga(X, 0, 0)
mult_in_gga(X, s(Y), Z) → U1_gga(X, Y, Z, mult_in_gga(X, Y, W))
U1_gga(X, Y, Z, mult_out_gga(X, Y, W)) → U2_gga(X, Y, Z, sum_in_gga(W, X, Z))
sum_in_gga(X, 0, X) → sum_out_gga(X, 0, X)
sum_in_gga(X, s(Y), s(Z)) → U3_gga(X, Y, Z, sum_in_gga(X, Y, Z))
U3_gga(X, Y, Z, sum_out_gga(X, Y, Z)) → sum_out_gga(X, s(Y), s(Z))
U2_gga(X, Y, Z, sum_out_gga(W, X, Z)) → mult_out_gga(X, s(Y), Z)

The argument filtering Pi contains the following mapping:
mult_in_gga(x1, x2, x3)  =  mult_in_gga(x1, x2)
0  =  0
mult_out_gga(x1, x2, x3)  =  mult_out_gga(x3)
s(x1)  =  s(x1)
U1_gga(x1, x2, x3, x4)  =  U1_gga(x1, x4)
U2_gga(x1, x2, x3, x4)  =  U2_gga(x4)
sum_in_gga(x1, x2, x3)  =  sum_in_gga(x1, x2)
sum_out_gga(x1, x2, x3)  =  sum_out_gga(x3)
U3_gga(x1, x2, x3, x4)  =  U3_gga(x4)
U2_GGA(x1, x2, x3, x4)  =  U2_GGA(x4)
SUM_IN_GGA(x1, x2, x3)  =  SUM_IN_GGA(x1, x2)
MULT_IN_GGA(x1, x2, x3)  =  MULT_IN_GGA(x1, x2)
U1_GGA(x1, x2, x3, x4)  =  U1_GGA(x1, x4)
U3_GGA(x1, x2, x3, x4)  =  U3_GGA(x4)

We have to consider all (P,R,Pi)-chains
The approximation of the Dependency Graph [30] contains 2 SCCs with 4 less nodes.

↳ Prolog
  ↳ PrologToPiTRSProof
    ↳ PiTRS
      ↳ DependencyPairsProof
        ↳ PiDP
          ↳ DependencyGraphProof
            ↳ AND
PiDP
                ↳ UsableRulesProof
              ↳ PiDP

Pi DP problem:
The TRS P consists of the following rules:

SUM_IN_GGA(X, s(Y), s(Z)) → SUM_IN_GGA(X, Y, Z)

The TRS R consists of the following rules:

mult_in_gga(X, 0, 0) → mult_out_gga(X, 0, 0)
mult_in_gga(X, s(Y), Z) → U1_gga(X, Y, Z, mult_in_gga(X, Y, W))
U1_gga(X, Y, Z, mult_out_gga(X, Y, W)) → U2_gga(X, Y, Z, sum_in_gga(W, X, Z))
sum_in_gga(X, 0, X) → sum_out_gga(X, 0, X)
sum_in_gga(X, s(Y), s(Z)) → U3_gga(X, Y, Z, sum_in_gga(X, Y, Z))
U3_gga(X, Y, Z, sum_out_gga(X, Y, Z)) → sum_out_gga(X, s(Y), s(Z))
U2_gga(X, Y, Z, sum_out_gga(W, X, Z)) → mult_out_gga(X, s(Y), Z)

The argument filtering Pi contains the following mapping:
mult_in_gga(x1, x2, x3)  =  mult_in_gga(x1, x2)
0  =  0
mult_out_gga(x1, x2, x3)  =  mult_out_gga(x3)
s(x1)  =  s(x1)
U1_gga(x1, x2, x3, x4)  =  U1_gga(x1, x4)
U2_gga(x1, x2, x3, x4)  =  U2_gga(x4)
sum_in_gga(x1, x2, x3)  =  sum_in_gga(x1, x2)
sum_out_gga(x1, x2, x3)  =  sum_out_gga(x3)
U3_gga(x1, x2, x3, x4)  =  U3_gga(x4)
SUM_IN_GGA(x1, x2, x3)  =  SUM_IN_GGA(x1, x2)

We have to consider all (P,R,Pi)-chains
For (infinitary) constructor rewriting [30] we can delete all non-usable rules from R.

↳ Prolog
  ↳ PrologToPiTRSProof
    ↳ PiTRS
      ↳ DependencyPairsProof
        ↳ PiDP
          ↳ DependencyGraphProof
            ↳ AND
              ↳ PiDP
                ↳ UsableRulesProof
PiDP
                    ↳ PiDPToQDPProof
              ↳ PiDP

Pi DP problem:
The TRS P consists of the following rules:

SUM_IN_GGA(X, s(Y), s(Z)) → SUM_IN_GGA(X, Y, Z)

R is empty.
The argument filtering Pi contains the following mapping:
s(x1)  =  s(x1)
SUM_IN_GGA(x1, x2, x3)  =  SUM_IN_GGA(x1, x2)

We have to consider all (P,R,Pi)-chains
Transforming (infinitary) constructor rewriting Pi-DP problem [30] into ordinary QDP problem [15] by application of Pi.

↳ Prolog
  ↳ PrologToPiTRSProof
    ↳ PiTRS
      ↳ DependencyPairsProof
        ↳ PiDP
          ↳ DependencyGraphProof
            ↳ AND
              ↳ PiDP
                ↳ UsableRulesProof
                  ↳ PiDP
                    ↳ PiDPToQDPProof
QDP
                        ↳ QDPSizeChangeProof
              ↳ PiDP

Q DP problem:
The TRS P consists of the following rules:

SUM_IN_GGA(X, s(Y)) → SUM_IN_GGA(X, Y)

R is empty.
Q is empty.
We have to consider all (P,Q,R)-chains.
By using the subterm criterion [20] together with the size-change analysis [32] we have proven that there are no infinite chains for this DP problem.

From the DPs we obtained the following set of size-change graphs:



↳ Prolog
  ↳ PrologToPiTRSProof
    ↳ PiTRS
      ↳ DependencyPairsProof
        ↳ PiDP
          ↳ DependencyGraphProof
            ↳ AND
              ↳ PiDP
PiDP
                ↳ UsableRulesProof

Pi DP problem:
The TRS P consists of the following rules:

MULT_IN_GGA(X, s(Y), Z) → MULT_IN_GGA(X, Y, W)

The TRS R consists of the following rules:

mult_in_gga(X, 0, 0) → mult_out_gga(X, 0, 0)
mult_in_gga(X, s(Y), Z) → U1_gga(X, Y, Z, mult_in_gga(X, Y, W))
U1_gga(X, Y, Z, mult_out_gga(X, Y, W)) → U2_gga(X, Y, Z, sum_in_gga(W, X, Z))
sum_in_gga(X, 0, X) → sum_out_gga(X, 0, X)
sum_in_gga(X, s(Y), s(Z)) → U3_gga(X, Y, Z, sum_in_gga(X, Y, Z))
U3_gga(X, Y, Z, sum_out_gga(X, Y, Z)) → sum_out_gga(X, s(Y), s(Z))
U2_gga(X, Y, Z, sum_out_gga(W, X, Z)) → mult_out_gga(X, s(Y), Z)

The argument filtering Pi contains the following mapping:
mult_in_gga(x1, x2, x3)  =  mult_in_gga(x1, x2)
0  =  0
mult_out_gga(x1, x2, x3)  =  mult_out_gga(x3)
s(x1)  =  s(x1)
U1_gga(x1, x2, x3, x4)  =  U1_gga(x1, x4)
U2_gga(x1, x2, x3, x4)  =  U2_gga(x4)
sum_in_gga(x1, x2, x3)  =  sum_in_gga(x1, x2)
sum_out_gga(x1, x2, x3)  =  sum_out_gga(x3)
U3_gga(x1, x2, x3, x4)  =  U3_gga(x4)
MULT_IN_GGA(x1, x2, x3)  =  MULT_IN_GGA(x1, x2)

We have to consider all (P,R,Pi)-chains
For (infinitary) constructor rewriting [30] we can delete all non-usable rules from R.

↳ Prolog
  ↳ PrologToPiTRSProof
    ↳ PiTRS
      ↳ DependencyPairsProof
        ↳ PiDP
          ↳ DependencyGraphProof
            ↳ AND
              ↳ PiDP
              ↳ PiDP
                ↳ UsableRulesProof
PiDP
                    ↳ PiDPToQDPProof

Pi DP problem:
The TRS P consists of the following rules:

MULT_IN_GGA(X, s(Y), Z) → MULT_IN_GGA(X, Y, W)

R is empty.
The argument filtering Pi contains the following mapping:
s(x1)  =  s(x1)
MULT_IN_GGA(x1, x2, x3)  =  MULT_IN_GGA(x1, x2)

We have to consider all (P,R,Pi)-chains
Transforming (infinitary) constructor rewriting Pi-DP problem [30] into ordinary QDP problem [15] by application of Pi.

↳ Prolog
  ↳ PrologToPiTRSProof
    ↳ PiTRS
      ↳ DependencyPairsProof
        ↳ PiDP
          ↳ DependencyGraphProof
            ↳ AND
              ↳ PiDP
              ↳ PiDP
                ↳ UsableRulesProof
                  ↳ PiDP
                    ↳ PiDPToQDPProof
QDP
                        ↳ QDPSizeChangeProof

Q DP problem:
The TRS P consists of the following rules:

MULT_IN_GGA(X, s(Y)) → MULT_IN_GGA(X, Y)

R is empty.
Q is empty.
We have to consider all (P,Q,R)-chains.
By using the subterm criterion [20] together with the size-change analysis [32] we have proven that there are no infinite chains for this DP problem.

From the DPs we obtained the following set of size-change graphs: