Left Termination of the query pattern perm_in_2(g, a) w.r.t. the given Prolog program could successfully be proven:



Prolog
  ↳ PrologToPiTRSProof

Clauses:

perm([], []).
perm(.(X, L), Z) :- ','(perm(L, Y), insert(X, Y, Z)).
insert(X, [], .(X, [])).
insert(X, L, .(X, L)).
insert(X, .(H, L1), .(H, L2)) :- insert(X, L1, L2).

Queries:

perm(g,a).

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

perm_in_ga([], []) → perm_out_ga([], [])
perm_in_ga(.(X, L), Z) → U1_ga(X, L, Z, perm_in_ga(L, Y))
U1_ga(X, L, Z, perm_out_ga(L, Y)) → U2_ga(X, L, Z, insert_in_gga(X, Y, Z))
insert_in_gga(X, [], .(X, [])) → insert_out_gga(X, [], .(X, []))
insert_in_gga(X, L, .(X, L)) → insert_out_gga(X, L, .(X, L))
insert_in_gga(X, .(H, L1), .(H, L2)) → U3_gga(X, H, L1, L2, insert_in_gga(X, L1, L2))
U3_gga(X, H, L1, L2, insert_out_gga(X, L1, L2)) → insert_out_gga(X, .(H, L1), .(H, L2))
U2_ga(X, L, Z, insert_out_gga(X, Y, Z)) → perm_out_ga(.(X, L), Z)

The argument filtering Pi contains the following mapping:
perm_in_ga(x1, x2)  =  perm_in_ga(x1)
[]  =  []
perm_out_ga(x1, x2)  =  perm_out_ga(x2)
.(x1, x2)  =  .(x1, x2)
U1_ga(x1, x2, x3, x4)  =  U1_ga(x1, x4)
U2_ga(x1, x2, x3, x4)  =  U2_ga(x4)
insert_in_gga(x1, x2, x3)  =  insert_in_gga(x1, x2)
insert_out_gga(x1, x2, x3)  =  insert_out_gga(x3)
U3_gga(x1, x2, x3, x4, x5)  =  U3_gga(x2, 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:

perm_in_ga([], []) → perm_out_ga([], [])
perm_in_ga(.(X, L), Z) → U1_ga(X, L, Z, perm_in_ga(L, Y))
U1_ga(X, L, Z, perm_out_ga(L, Y)) → U2_ga(X, L, Z, insert_in_gga(X, Y, Z))
insert_in_gga(X, [], .(X, [])) → insert_out_gga(X, [], .(X, []))
insert_in_gga(X, L, .(X, L)) → insert_out_gga(X, L, .(X, L))
insert_in_gga(X, .(H, L1), .(H, L2)) → U3_gga(X, H, L1, L2, insert_in_gga(X, L1, L2))
U3_gga(X, H, L1, L2, insert_out_gga(X, L1, L2)) → insert_out_gga(X, .(H, L1), .(H, L2))
U2_ga(X, L, Z, insert_out_gga(X, Y, Z)) → perm_out_ga(.(X, L), Z)

The argument filtering Pi contains the following mapping:
perm_in_ga(x1, x2)  =  perm_in_ga(x1)
[]  =  []
perm_out_ga(x1, x2)  =  perm_out_ga(x2)
.(x1, x2)  =  .(x1, x2)
U1_ga(x1, x2, x3, x4)  =  U1_ga(x1, x4)
U2_ga(x1, x2, x3, x4)  =  U2_ga(x4)
insert_in_gga(x1, x2, x3)  =  insert_in_gga(x1, x2)
insert_out_gga(x1, x2, x3)  =  insert_out_gga(x3)
U3_gga(x1, x2, x3, x4, x5)  =  U3_gga(x2, 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:

PERM_IN_GA(.(X, L), Z) → U1_GA(X, L, Z, perm_in_ga(L, Y))
PERM_IN_GA(.(X, L), Z) → PERM_IN_GA(L, Y)
U1_GA(X, L, Z, perm_out_ga(L, Y)) → U2_GA(X, L, Z, insert_in_gga(X, Y, Z))
U1_GA(X, L, Z, perm_out_ga(L, Y)) → INSERT_IN_GGA(X, Y, Z)
INSERT_IN_GGA(X, .(H, L1), .(H, L2)) → U3_GGA(X, H, L1, L2, insert_in_gga(X, L1, L2))
INSERT_IN_GGA(X, .(H, L1), .(H, L2)) → INSERT_IN_GGA(X, L1, L2)

The TRS R consists of the following rules:

perm_in_ga([], []) → perm_out_ga([], [])
perm_in_ga(.(X, L), Z) → U1_ga(X, L, Z, perm_in_ga(L, Y))
U1_ga(X, L, Z, perm_out_ga(L, Y)) → U2_ga(X, L, Z, insert_in_gga(X, Y, Z))
insert_in_gga(X, [], .(X, [])) → insert_out_gga(X, [], .(X, []))
insert_in_gga(X, L, .(X, L)) → insert_out_gga(X, L, .(X, L))
insert_in_gga(X, .(H, L1), .(H, L2)) → U3_gga(X, H, L1, L2, insert_in_gga(X, L1, L2))
U3_gga(X, H, L1, L2, insert_out_gga(X, L1, L2)) → insert_out_gga(X, .(H, L1), .(H, L2))
U2_ga(X, L, Z, insert_out_gga(X, Y, Z)) → perm_out_ga(.(X, L), Z)

The argument filtering Pi contains the following mapping:
perm_in_ga(x1, x2)  =  perm_in_ga(x1)
[]  =  []
perm_out_ga(x1, x2)  =  perm_out_ga(x2)
.(x1, x2)  =  .(x1, x2)
U1_ga(x1, x2, x3, x4)  =  U1_ga(x1, x4)
U2_ga(x1, x2, x3, x4)  =  U2_ga(x4)
insert_in_gga(x1, x2, x3)  =  insert_in_gga(x1, x2)
insert_out_gga(x1, x2, x3)  =  insert_out_gga(x3)
U3_gga(x1, x2, x3, x4, x5)  =  U3_gga(x2, x5)
U3_GGA(x1, x2, x3, x4, x5)  =  U3_GGA(x2, x5)
INSERT_IN_GGA(x1, x2, x3)  =  INSERT_IN_GGA(x1, x2)
U2_GA(x1, x2, x3, x4)  =  U2_GA(x4)
U1_GA(x1, x2, x3, x4)  =  U1_GA(x1, x4)
PERM_IN_GA(x1, x2)  =  PERM_IN_GA(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:

PERM_IN_GA(.(X, L), Z) → U1_GA(X, L, Z, perm_in_ga(L, Y))
PERM_IN_GA(.(X, L), Z) → PERM_IN_GA(L, Y)
U1_GA(X, L, Z, perm_out_ga(L, Y)) → U2_GA(X, L, Z, insert_in_gga(X, Y, Z))
U1_GA(X, L, Z, perm_out_ga(L, Y)) → INSERT_IN_GGA(X, Y, Z)
INSERT_IN_GGA(X, .(H, L1), .(H, L2)) → U3_GGA(X, H, L1, L2, insert_in_gga(X, L1, L2))
INSERT_IN_GGA(X, .(H, L1), .(H, L2)) → INSERT_IN_GGA(X, L1, L2)

The TRS R consists of the following rules:

perm_in_ga([], []) → perm_out_ga([], [])
perm_in_ga(.(X, L), Z) → U1_ga(X, L, Z, perm_in_ga(L, Y))
U1_ga(X, L, Z, perm_out_ga(L, Y)) → U2_ga(X, L, Z, insert_in_gga(X, Y, Z))
insert_in_gga(X, [], .(X, [])) → insert_out_gga(X, [], .(X, []))
insert_in_gga(X, L, .(X, L)) → insert_out_gga(X, L, .(X, L))
insert_in_gga(X, .(H, L1), .(H, L2)) → U3_gga(X, H, L1, L2, insert_in_gga(X, L1, L2))
U3_gga(X, H, L1, L2, insert_out_gga(X, L1, L2)) → insert_out_gga(X, .(H, L1), .(H, L2))
U2_ga(X, L, Z, insert_out_gga(X, Y, Z)) → perm_out_ga(.(X, L), Z)

The argument filtering Pi contains the following mapping:
perm_in_ga(x1, x2)  =  perm_in_ga(x1)
[]  =  []
perm_out_ga(x1, x2)  =  perm_out_ga(x2)
.(x1, x2)  =  .(x1, x2)
U1_ga(x1, x2, x3, x4)  =  U1_ga(x1, x4)
U2_ga(x1, x2, x3, x4)  =  U2_ga(x4)
insert_in_gga(x1, x2, x3)  =  insert_in_gga(x1, x2)
insert_out_gga(x1, x2, x3)  =  insert_out_gga(x3)
U3_gga(x1, x2, x3, x4, x5)  =  U3_gga(x2, x5)
U3_GGA(x1, x2, x3, x4, x5)  =  U3_GGA(x2, x5)
INSERT_IN_GGA(x1, x2, x3)  =  INSERT_IN_GGA(x1, x2)
U2_GA(x1, x2, x3, x4)  =  U2_GA(x4)
U1_GA(x1, x2, x3, x4)  =  U1_GA(x1, x4)
PERM_IN_GA(x1, x2)  =  PERM_IN_GA(x1)

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:

INSERT_IN_GGA(X, .(H, L1), .(H, L2)) → INSERT_IN_GGA(X, L1, L2)

The TRS R consists of the following rules:

perm_in_ga([], []) → perm_out_ga([], [])
perm_in_ga(.(X, L), Z) → U1_ga(X, L, Z, perm_in_ga(L, Y))
U1_ga(X, L, Z, perm_out_ga(L, Y)) → U2_ga(X, L, Z, insert_in_gga(X, Y, Z))
insert_in_gga(X, [], .(X, [])) → insert_out_gga(X, [], .(X, []))
insert_in_gga(X, L, .(X, L)) → insert_out_gga(X, L, .(X, L))
insert_in_gga(X, .(H, L1), .(H, L2)) → U3_gga(X, H, L1, L2, insert_in_gga(X, L1, L2))
U3_gga(X, H, L1, L2, insert_out_gga(X, L1, L2)) → insert_out_gga(X, .(H, L1), .(H, L2))
U2_ga(X, L, Z, insert_out_gga(X, Y, Z)) → perm_out_ga(.(X, L), Z)

The argument filtering Pi contains the following mapping:
perm_in_ga(x1, x2)  =  perm_in_ga(x1)
[]  =  []
perm_out_ga(x1, x2)  =  perm_out_ga(x2)
.(x1, x2)  =  .(x1, x2)
U1_ga(x1, x2, x3, x4)  =  U1_ga(x1, x4)
U2_ga(x1, x2, x3, x4)  =  U2_ga(x4)
insert_in_gga(x1, x2, x3)  =  insert_in_gga(x1, x2)
insert_out_gga(x1, x2, x3)  =  insert_out_gga(x3)
U3_gga(x1, x2, x3, x4, x5)  =  U3_gga(x2, x5)
INSERT_IN_GGA(x1, x2, x3)  =  INSERT_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:

INSERT_IN_GGA(X, .(H, L1), .(H, L2)) → INSERT_IN_GGA(X, L1, L2)

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

INSERT_IN_GGA(X, .(H, L1)) → INSERT_IN_GGA(X, L1)

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:

PERM_IN_GA(.(X, L), Z) → PERM_IN_GA(L, Y)

The TRS R consists of the following rules:

perm_in_ga([], []) → perm_out_ga([], [])
perm_in_ga(.(X, L), Z) → U1_ga(X, L, Z, perm_in_ga(L, Y))
U1_ga(X, L, Z, perm_out_ga(L, Y)) → U2_ga(X, L, Z, insert_in_gga(X, Y, Z))
insert_in_gga(X, [], .(X, [])) → insert_out_gga(X, [], .(X, []))
insert_in_gga(X, L, .(X, L)) → insert_out_gga(X, L, .(X, L))
insert_in_gga(X, .(H, L1), .(H, L2)) → U3_gga(X, H, L1, L2, insert_in_gga(X, L1, L2))
U3_gga(X, H, L1, L2, insert_out_gga(X, L1, L2)) → insert_out_gga(X, .(H, L1), .(H, L2))
U2_ga(X, L, Z, insert_out_gga(X, Y, Z)) → perm_out_ga(.(X, L), Z)

The argument filtering Pi contains the following mapping:
perm_in_ga(x1, x2)  =  perm_in_ga(x1)
[]  =  []
perm_out_ga(x1, x2)  =  perm_out_ga(x2)
.(x1, x2)  =  .(x1, x2)
U1_ga(x1, x2, x3, x4)  =  U1_ga(x1, x4)
U2_ga(x1, x2, x3, x4)  =  U2_ga(x4)
insert_in_gga(x1, x2, x3)  =  insert_in_gga(x1, x2)
insert_out_gga(x1, x2, x3)  =  insert_out_gga(x3)
U3_gga(x1, x2, x3, x4, x5)  =  U3_gga(x2, x5)
PERM_IN_GA(x1, x2)  =  PERM_IN_GA(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
            ↳ AND
              ↳ PiDP
              ↳ PiDP
                ↳ UsableRulesProof
PiDP
                    ↳ PiDPToQDPProof

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

PERM_IN_GA(.(X, L), Z) → PERM_IN_GA(L, Y)

R is empty.
The argument filtering Pi contains the following mapping:
.(x1, x2)  =  .(x1, x2)
PERM_IN_GA(x1, x2)  =  PERM_IN_GA(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
            ↳ AND
              ↳ PiDP
              ↳ PiDP
                ↳ UsableRulesProof
                  ↳ PiDP
                    ↳ PiDPToQDPProof
QDP
                        ↳ QDPSizeChangeProof

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

PERM_IN_GA(.(X, L)) → PERM_IN_GA(L)

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: