Left Termination of the query pattern plus_in_3(g, a, a) w.r.t. the given Prolog program could successfully be proven:



Prolog
  ↳ PrologToPiTRSProof

Clauses:

p(s(X), X).
plus(0, Y, Y).
plus(s(X), Y, s(Z)) :- ','(p(s(X), U), plus(U, Y, Z)).

Queries:

plus(g,a,a).

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

plus_in_gaa(0, Y, Y) → plus_out_gaa(0, Y, Y)
plus_in_gaa(s(X), Y, s(Z)) → U1_gaa(X, Y, Z, p_in_ga(s(X), U))
p_in_ga(s(X), X) → p_out_ga(s(X), X)
U1_gaa(X, Y, Z, p_out_ga(s(X), U)) → U2_gaa(X, Y, Z, U, plus_in_gaa(U, Y, Z))
U2_gaa(X, Y, Z, U, plus_out_gaa(U, Y, Z)) → plus_out_gaa(s(X), Y, s(Z))

The argument filtering Pi contains the following mapping:
plus_in_gaa(x1, x2, x3)  =  plus_in_gaa(x1)
0  =  0
plus_out_gaa(x1, x2, x3)  =  plus_out_gaa
s(x1)  =  s(x1)
U1_gaa(x1, x2, x3, x4)  =  U1_gaa(x4)
p_in_ga(x1, x2)  =  p_in_ga(x1)
p_out_ga(x1, x2)  =  p_out_ga(x2)
U2_gaa(x1, x2, x3, x4, x5)  =  U2_gaa(x5)

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:

plus_in_gaa(0, Y, Y) → plus_out_gaa(0, Y, Y)
plus_in_gaa(s(X), Y, s(Z)) → U1_gaa(X, Y, Z, p_in_ga(s(X), U))
p_in_ga(s(X), X) → p_out_ga(s(X), X)
U1_gaa(X, Y, Z, p_out_ga(s(X), U)) → U2_gaa(X, Y, Z, U, plus_in_gaa(U, Y, Z))
U2_gaa(X, Y, Z, U, plus_out_gaa(U, Y, Z)) → plus_out_gaa(s(X), Y, s(Z))

The argument filtering Pi contains the following mapping:
plus_in_gaa(x1, x2, x3)  =  plus_in_gaa(x1)
0  =  0
plus_out_gaa(x1, x2, x3)  =  plus_out_gaa
s(x1)  =  s(x1)
U1_gaa(x1, x2, x3, x4)  =  U1_gaa(x4)
p_in_ga(x1, x2)  =  p_in_ga(x1)
p_out_ga(x1, x2)  =  p_out_ga(x2)
U2_gaa(x1, x2, x3, x4, x5)  =  U2_gaa(x5)


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

PLUS_IN_GAA(s(X), Y, s(Z)) → U1_GAA(X, Y, Z, p_in_ga(s(X), U))
PLUS_IN_GAA(s(X), Y, s(Z)) → P_IN_GA(s(X), U)
U1_GAA(X, Y, Z, p_out_ga(s(X), U)) → U2_GAA(X, Y, Z, U, plus_in_gaa(U, Y, Z))
U1_GAA(X, Y, Z, p_out_ga(s(X), U)) → PLUS_IN_GAA(U, Y, Z)

The TRS R consists of the following rules:

plus_in_gaa(0, Y, Y) → plus_out_gaa(0, Y, Y)
plus_in_gaa(s(X), Y, s(Z)) → U1_gaa(X, Y, Z, p_in_ga(s(X), U))
p_in_ga(s(X), X) → p_out_ga(s(X), X)
U1_gaa(X, Y, Z, p_out_ga(s(X), U)) → U2_gaa(X, Y, Z, U, plus_in_gaa(U, Y, Z))
U2_gaa(X, Y, Z, U, plus_out_gaa(U, Y, Z)) → plus_out_gaa(s(X), Y, s(Z))

The argument filtering Pi contains the following mapping:
plus_in_gaa(x1, x2, x3)  =  plus_in_gaa(x1)
0  =  0
plus_out_gaa(x1, x2, x3)  =  plus_out_gaa
s(x1)  =  s(x1)
U1_gaa(x1, x2, x3, x4)  =  U1_gaa(x4)
p_in_ga(x1, x2)  =  p_in_ga(x1)
p_out_ga(x1, x2)  =  p_out_ga(x2)
U2_gaa(x1, x2, x3, x4, x5)  =  U2_gaa(x5)
P_IN_GA(x1, x2)  =  P_IN_GA(x1)
U2_GAA(x1, x2, x3, x4, x5)  =  U2_GAA(x5)
U1_GAA(x1, x2, x3, x4)  =  U1_GAA(x4)
PLUS_IN_GAA(x1, x2, x3)  =  PLUS_IN_GAA(x1)

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:

PLUS_IN_GAA(s(X), Y, s(Z)) → U1_GAA(X, Y, Z, p_in_ga(s(X), U))
PLUS_IN_GAA(s(X), Y, s(Z)) → P_IN_GA(s(X), U)
U1_GAA(X, Y, Z, p_out_ga(s(X), U)) → U2_GAA(X, Y, Z, U, plus_in_gaa(U, Y, Z))
U1_GAA(X, Y, Z, p_out_ga(s(X), U)) → PLUS_IN_GAA(U, Y, Z)

The TRS R consists of the following rules:

plus_in_gaa(0, Y, Y) → plus_out_gaa(0, Y, Y)
plus_in_gaa(s(X), Y, s(Z)) → U1_gaa(X, Y, Z, p_in_ga(s(X), U))
p_in_ga(s(X), X) → p_out_ga(s(X), X)
U1_gaa(X, Y, Z, p_out_ga(s(X), U)) → U2_gaa(X, Y, Z, U, plus_in_gaa(U, Y, Z))
U2_gaa(X, Y, Z, U, plus_out_gaa(U, Y, Z)) → plus_out_gaa(s(X), Y, s(Z))

The argument filtering Pi contains the following mapping:
plus_in_gaa(x1, x2, x3)  =  plus_in_gaa(x1)
0  =  0
plus_out_gaa(x1, x2, x3)  =  plus_out_gaa
s(x1)  =  s(x1)
U1_gaa(x1, x2, x3, x4)  =  U1_gaa(x4)
p_in_ga(x1, x2)  =  p_in_ga(x1)
p_out_ga(x1, x2)  =  p_out_ga(x2)
U2_gaa(x1, x2, x3, x4, x5)  =  U2_gaa(x5)
P_IN_GA(x1, x2)  =  P_IN_GA(x1)
U2_GAA(x1, x2, x3, x4, x5)  =  U2_GAA(x5)
U1_GAA(x1, x2, x3, x4)  =  U1_GAA(x4)
PLUS_IN_GAA(x1, x2, x3)  =  PLUS_IN_GAA(x1)

We have to consider all (P,R,Pi)-chains
The approximation of the Dependency Graph [30] contains 1 SCC with 2 less nodes.

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

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

U1_GAA(X, Y, Z, p_out_ga(s(X), U)) → PLUS_IN_GAA(U, Y, Z)
PLUS_IN_GAA(s(X), Y, s(Z)) → U1_GAA(X, Y, Z, p_in_ga(s(X), U))

The TRS R consists of the following rules:

plus_in_gaa(0, Y, Y) → plus_out_gaa(0, Y, Y)
plus_in_gaa(s(X), Y, s(Z)) → U1_gaa(X, Y, Z, p_in_ga(s(X), U))
p_in_ga(s(X), X) → p_out_ga(s(X), X)
U1_gaa(X, Y, Z, p_out_ga(s(X), U)) → U2_gaa(X, Y, Z, U, plus_in_gaa(U, Y, Z))
U2_gaa(X, Y, Z, U, plus_out_gaa(U, Y, Z)) → plus_out_gaa(s(X), Y, s(Z))

The argument filtering Pi contains the following mapping:
plus_in_gaa(x1, x2, x3)  =  plus_in_gaa(x1)
0  =  0
plus_out_gaa(x1, x2, x3)  =  plus_out_gaa
s(x1)  =  s(x1)
U1_gaa(x1, x2, x3, x4)  =  U1_gaa(x4)
p_in_ga(x1, x2)  =  p_in_ga(x1)
p_out_ga(x1, x2)  =  p_out_ga(x2)
U2_gaa(x1, x2, x3, x4, x5)  =  U2_gaa(x5)
U1_GAA(x1, x2, x3, x4)  =  U1_GAA(x4)
PLUS_IN_GAA(x1, x2, x3)  =  PLUS_IN_GAA(x1)

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
            ↳ PiDP
              ↳ UsableRulesProof
PiDP
                  ↳ PiDPToQDPProof

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

U1_GAA(X, Y, Z, p_out_ga(s(X), U)) → PLUS_IN_GAA(U, Y, Z)
PLUS_IN_GAA(s(X), Y, s(Z)) → U1_GAA(X, Y, Z, p_in_ga(s(X), U))

The TRS R consists of the following rules:

p_in_ga(s(X), X) → p_out_ga(s(X), X)

The argument filtering Pi contains the following mapping:
s(x1)  =  s(x1)
p_in_ga(x1, x2)  =  p_in_ga(x1)
p_out_ga(x1, x2)  =  p_out_ga(x2)
U1_GAA(x1, x2, x3, x4)  =  U1_GAA(x4)
PLUS_IN_GAA(x1, x2, x3)  =  PLUS_IN_GAA(x1)

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
            ↳ PiDP
              ↳ UsableRulesProof
                ↳ PiDP
                  ↳ PiDPToQDPProof
QDP
                      ↳ RuleRemovalProof

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

PLUS_IN_GAA(s(X)) → U1_GAA(p_in_ga(s(X)))
U1_GAA(p_out_ga(U)) → PLUS_IN_GAA(U)

The TRS R consists of the following rules:

p_in_ga(s(X)) → p_out_ga(X)

The set Q consists of the following terms:

p_in_ga(x0)

We have to consider all (P,Q,R)-chains.
By using the rule removal processor [15] with the following polynomial ordering [25], at least one Dependency Pair or term rewrite system rule of this QDP problem can be strictly oriented.

Strictly oriented rules of the TRS R:

p_in_ga(s(X)) → p_out_ga(X)

Used ordering: POLO with Polynomial interpretation [25]:

POL(PLUS_IN_GAA(x1)) = x1   
POL(U1_GAA(x1)) = x1   
POL(p_in_ga(x1)) = x1   
POL(p_out_ga(x1)) = 2·x1   
POL(s(x1)) = 2 + 2·x1   



↳ Prolog
  ↳ PrologToPiTRSProof
    ↳ PiTRS
      ↳ DependencyPairsProof
        ↳ PiDP
          ↳ DependencyGraphProof
            ↳ PiDP
              ↳ UsableRulesProof
                ↳ PiDP
                  ↳ PiDPToQDPProof
                    ↳ QDP
                      ↳ RuleRemovalProof
QDP
                          ↳ DependencyGraphProof

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

PLUS_IN_GAA(s(X)) → U1_GAA(p_in_ga(s(X)))
U1_GAA(p_out_ga(U)) → PLUS_IN_GAA(U)

R is empty.
The set Q consists of the following terms:

p_in_ga(x0)

We have to consider all (P,Q,R)-chains.
The approximation of the Dependency Graph [15,17,22] contains 0 SCCs with 2 less nodes.