Left Termination of the query pattern append3(b,b,b,f) w.r.t. the given Prolog program could successfully be proven:



PROLOG
  ↳ PrologToPiTRSProof

append3({}0, L, L).
append3(.2(H, L1), L2, .2(H, L3)) :- append3(L1, L2, L3).
append34(A, B, C, D) :- append3(A, B, E), append3(E, C, D).


With regard to the inferred argument filtering the predicates were used in the following modes:
append34: (b,b,b,f)
append3: (b,b,f)
Transforming PROLOG into the following Term Rewriting System:
Pi-finite rewrite system:
The TRS R consists of the following rules:


append3_4_in_ggga4(A, B, C, D) -> if_append3_4_in_1_ggga5(A, B, C, D, append_3_in_gga3(A, B, E))
append_3_in_gga3([]_0, L, L) -> append_3_out_gga3([]_0, L, L)
append_3_in_gga3(._22(H, L1), L2, ._22(H, L3)) -> if_append_3_in_1_gga5(H, L1, L2, L3, append_3_in_gga3(L1, L2, L3))
if_append_3_in_1_gga5(H, L1, L2, L3, append_3_out_gga3(L1, L2, L3)) -> append_3_out_gga3(._22(H, L1), L2, ._22(H, L3))
if_append3_4_in_1_ggga5(A, B, C, D, append_3_out_gga3(A, B, E)) -> if_append3_4_in_2_ggga6(A, B, C, D, E, append_3_in_gga3(E, C, D))
if_append3_4_in_2_ggga6(A, B, C, D, E, append_3_out_gga3(E, C, D)) -> append3_4_out_ggga4(A, B, C, D)

The argument filtering Pi contains the following mapping:
append3_4_in_ggga4(x1, x2, x3, x4)  =  append3_4_in_ggga3(x1, x2, x3)
[]_0  =  []_0
._22(x1, x2)  =  ._22(x1, x2)
if_append3_4_in_1_ggga5(x1, x2, x3, x4, x5)  =  if_append3_4_in_1_ggga2(x3, x5)
append_3_in_gga3(x1, x2, x3)  =  append_3_in_gga2(x1, x2)
append_3_out_gga3(x1, x2, x3)  =  append_3_out_gga1(x3)
if_append_3_in_1_gga5(x1, x2, x3, x4, x5)  =  if_append_3_in_1_gga2(x1, x5)
if_append3_4_in_2_ggga6(x1, x2, x3, x4, x5, x6)  =  if_append3_4_in_2_ggga1(x6)
append3_4_out_ggga4(x1, x2, x3, x4)  =  append3_4_out_ggga1(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:

append3_4_in_ggga4(A, B, C, D) -> if_append3_4_in_1_ggga5(A, B, C, D, append_3_in_gga3(A, B, E))
append_3_in_gga3([]_0, L, L) -> append_3_out_gga3([]_0, L, L)
append_3_in_gga3(._22(H, L1), L2, ._22(H, L3)) -> if_append_3_in_1_gga5(H, L1, L2, L3, append_3_in_gga3(L1, L2, L3))
if_append_3_in_1_gga5(H, L1, L2, L3, append_3_out_gga3(L1, L2, L3)) -> append_3_out_gga3(._22(H, L1), L2, ._22(H, L3))
if_append3_4_in_1_ggga5(A, B, C, D, append_3_out_gga3(A, B, E)) -> if_append3_4_in_2_ggga6(A, B, C, D, E, append_3_in_gga3(E, C, D))
if_append3_4_in_2_ggga6(A, B, C, D, E, append_3_out_gga3(E, C, D)) -> append3_4_out_ggga4(A, B, C, D)

The argument filtering Pi contains the following mapping:
append3_4_in_ggga4(x1, x2, x3, x4)  =  append3_4_in_ggga3(x1, x2, x3)
[]_0  =  []_0
._22(x1, x2)  =  ._22(x1, x2)
if_append3_4_in_1_ggga5(x1, x2, x3, x4, x5)  =  if_append3_4_in_1_ggga2(x3, x5)
append_3_in_gga3(x1, x2, x3)  =  append_3_in_gga2(x1, x2)
append_3_out_gga3(x1, x2, x3)  =  append_3_out_gga1(x3)
if_append_3_in_1_gga5(x1, x2, x3, x4, x5)  =  if_append_3_in_1_gga2(x1, x5)
if_append3_4_in_2_ggga6(x1, x2, x3, x4, x5, x6)  =  if_append3_4_in_2_ggga1(x6)
append3_4_out_ggga4(x1, x2, x3, x4)  =  append3_4_out_ggga1(x4)


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

APPEND3_4_IN_GGGA4(A, B, C, D) -> IF_APPEND3_4_IN_1_GGGA5(A, B, C, D, append_3_in_gga3(A, B, E))
APPEND3_4_IN_GGGA4(A, B, C, D) -> APPEND_3_IN_GGA3(A, B, E)
APPEND_3_IN_GGA3(._22(H, L1), L2, ._22(H, L3)) -> IF_APPEND_3_IN_1_GGA5(H, L1, L2, L3, append_3_in_gga3(L1, L2, L3))
APPEND_3_IN_GGA3(._22(H, L1), L2, ._22(H, L3)) -> APPEND_3_IN_GGA3(L1, L2, L3)
IF_APPEND3_4_IN_1_GGGA5(A, B, C, D, append_3_out_gga3(A, B, E)) -> IF_APPEND3_4_IN_2_GGGA6(A, B, C, D, E, append_3_in_gga3(E, C, D))
IF_APPEND3_4_IN_1_GGGA5(A, B, C, D, append_3_out_gga3(A, B, E)) -> APPEND_3_IN_GGA3(E, C, D)

The TRS R consists of the following rules:

append3_4_in_ggga4(A, B, C, D) -> if_append3_4_in_1_ggga5(A, B, C, D, append_3_in_gga3(A, B, E))
append_3_in_gga3([]_0, L, L) -> append_3_out_gga3([]_0, L, L)
append_3_in_gga3(._22(H, L1), L2, ._22(H, L3)) -> if_append_3_in_1_gga5(H, L1, L2, L3, append_3_in_gga3(L1, L2, L3))
if_append_3_in_1_gga5(H, L1, L2, L3, append_3_out_gga3(L1, L2, L3)) -> append_3_out_gga3(._22(H, L1), L2, ._22(H, L3))
if_append3_4_in_1_ggga5(A, B, C, D, append_3_out_gga3(A, B, E)) -> if_append3_4_in_2_ggga6(A, B, C, D, E, append_3_in_gga3(E, C, D))
if_append3_4_in_2_ggga6(A, B, C, D, E, append_3_out_gga3(E, C, D)) -> append3_4_out_ggga4(A, B, C, D)

The argument filtering Pi contains the following mapping:
append3_4_in_ggga4(x1, x2, x3, x4)  =  append3_4_in_ggga3(x1, x2, x3)
[]_0  =  []_0
._22(x1, x2)  =  ._22(x1, x2)
if_append3_4_in_1_ggga5(x1, x2, x3, x4, x5)  =  if_append3_4_in_1_ggga2(x3, x5)
append_3_in_gga3(x1, x2, x3)  =  append_3_in_gga2(x1, x2)
append_3_out_gga3(x1, x2, x3)  =  append_3_out_gga1(x3)
if_append_3_in_1_gga5(x1, x2, x3, x4, x5)  =  if_append_3_in_1_gga2(x1, x5)
if_append3_4_in_2_ggga6(x1, x2, x3, x4, x5, x6)  =  if_append3_4_in_2_ggga1(x6)
append3_4_out_ggga4(x1, x2, x3, x4)  =  append3_4_out_ggga1(x4)
IF_APPEND3_4_IN_2_GGGA6(x1, x2, x3, x4, x5, x6)  =  IF_APPEND3_4_IN_2_GGGA1(x6)
IF_APPEND_3_IN_1_GGA5(x1, x2, x3, x4, x5)  =  IF_APPEND_3_IN_1_GGA2(x1, x5)
IF_APPEND3_4_IN_1_GGGA5(x1, x2, x3, x4, x5)  =  IF_APPEND3_4_IN_1_GGGA2(x3, x5)
APPEND3_4_IN_GGGA4(x1, x2, x3, x4)  =  APPEND3_4_IN_GGGA3(x1, x2, x3)
APPEND_3_IN_GGA3(x1, x2, x3)  =  APPEND_3_IN_GGA2(x1, x2)

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:

APPEND3_4_IN_GGGA4(A, B, C, D) -> IF_APPEND3_4_IN_1_GGGA5(A, B, C, D, append_3_in_gga3(A, B, E))
APPEND3_4_IN_GGGA4(A, B, C, D) -> APPEND_3_IN_GGA3(A, B, E)
APPEND_3_IN_GGA3(._22(H, L1), L2, ._22(H, L3)) -> IF_APPEND_3_IN_1_GGA5(H, L1, L2, L3, append_3_in_gga3(L1, L2, L3))
APPEND_3_IN_GGA3(._22(H, L1), L2, ._22(H, L3)) -> APPEND_3_IN_GGA3(L1, L2, L3)
IF_APPEND3_4_IN_1_GGGA5(A, B, C, D, append_3_out_gga3(A, B, E)) -> IF_APPEND3_4_IN_2_GGGA6(A, B, C, D, E, append_3_in_gga3(E, C, D))
IF_APPEND3_4_IN_1_GGGA5(A, B, C, D, append_3_out_gga3(A, B, E)) -> APPEND_3_IN_GGA3(E, C, D)

The TRS R consists of the following rules:

append3_4_in_ggga4(A, B, C, D) -> if_append3_4_in_1_ggga5(A, B, C, D, append_3_in_gga3(A, B, E))
append_3_in_gga3([]_0, L, L) -> append_3_out_gga3([]_0, L, L)
append_3_in_gga3(._22(H, L1), L2, ._22(H, L3)) -> if_append_3_in_1_gga5(H, L1, L2, L3, append_3_in_gga3(L1, L2, L3))
if_append_3_in_1_gga5(H, L1, L2, L3, append_3_out_gga3(L1, L2, L3)) -> append_3_out_gga3(._22(H, L1), L2, ._22(H, L3))
if_append3_4_in_1_ggga5(A, B, C, D, append_3_out_gga3(A, B, E)) -> if_append3_4_in_2_ggga6(A, B, C, D, E, append_3_in_gga3(E, C, D))
if_append3_4_in_2_ggga6(A, B, C, D, E, append_3_out_gga3(E, C, D)) -> append3_4_out_ggga4(A, B, C, D)

The argument filtering Pi contains the following mapping:
append3_4_in_ggga4(x1, x2, x3, x4)  =  append3_4_in_ggga3(x1, x2, x3)
[]_0  =  []_0
._22(x1, x2)  =  ._22(x1, x2)
if_append3_4_in_1_ggga5(x1, x2, x3, x4, x5)  =  if_append3_4_in_1_ggga2(x3, x5)
append_3_in_gga3(x1, x2, x3)  =  append_3_in_gga2(x1, x2)
append_3_out_gga3(x1, x2, x3)  =  append_3_out_gga1(x3)
if_append_3_in_1_gga5(x1, x2, x3, x4, x5)  =  if_append_3_in_1_gga2(x1, x5)
if_append3_4_in_2_ggga6(x1, x2, x3, x4, x5, x6)  =  if_append3_4_in_2_ggga1(x6)
append3_4_out_ggga4(x1, x2, x3, x4)  =  append3_4_out_ggga1(x4)
IF_APPEND3_4_IN_2_GGGA6(x1, x2, x3, x4, x5, x6)  =  IF_APPEND3_4_IN_2_GGGA1(x6)
IF_APPEND_3_IN_1_GGA5(x1, x2, x3, x4, x5)  =  IF_APPEND_3_IN_1_GGA2(x1, x5)
IF_APPEND3_4_IN_1_GGGA5(x1, x2, x3, x4, x5)  =  IF_APPEND3_4_IN_1_GGGA2(x3, x5)
APPEND3_4_IN_GGGA4(x1, x2, x3, x4)  =  APPEND3_4_IN_GGGA3(x1, x2, x3)
APPEND_3_IN_GGA3(x1, x2, x3)  =  APPEND_3_IN_GGA2(x1, x2)

We have to consider all (P,R,Pi)-chains
The approximation of the Dependency Graph contains 1 SCC with 5 less nodes.

↳ PROLOG
  ↳ PrologToPiTRSProof
    ↳ PiTRS
      ↳ DependencyPairsProof
        ↳ PiDP
          ↳ DependencyGraphProof
PiDP
              ↳ UsableRulesProof

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

APPEND_3_IN_GGA3(._22(H, L1), L2, ._22(H, L3)) -> APPEND_3_IN_GGA3(L1, L2, L3)

The TRS R consists of the following rules:

append3_4_in_ggga4(A, B, C, D) -> if_append3_4_in_1_ggga5(A, B, C, D, append_3_in_gga3(A, B, E))
append_3_in_gga3([]_0, L, L) -> append_3_out_gga3([]_0, L, L)
append_3_in_gga3(._22(H, L1), L2, ._22(H, L3)) -> if_append_3_in_1_gga5(H, L1, L2, L3, append_3_in_gga3(L1, L2, L3))
if_append_3_in_1_gga5(H, L1, L2, L3, append_3_out_gga3(L1, L2, L3)) -> append_3_out_gga3(._22(H, L1), L2, ._22(H, L3))
if_append3_4_in_1_ggga5(A, B, C, D, append_3_out_gga3(A, B, E)) -> if_append3_4_in_2_ggga6(A, B, C, D, E, append_3_in_gga3(E, C, D))
if_append3_4_in_2_ggga6(A, B, C, D, E, append_3_out_gga3(E, C, D)) -> append3_4_out_ggga4(A, B, C, D)

The argument filtering Pi contains the following mapping:
append3_4_in_ggga4(x1, x2, x3, x4)  =  append3_4_in_ggga3(x1, x2, x3)
[]_0  =  []_0
._22(x1, x2)  =  ._22(x1, x2)
if_append3_4_in_1_ggga5(x1, x2, x3, x4, x5)  =  if_append3_4_in_1_ggga2(x3, x5)
append_3_in_gga3(x1, x2, x3)  =  append_3_in_gga2(x1, x2)
append_3_out_gga3(x1, x2, x3)  =  append_3_out_gga1(x3)
if_append_3_in_1_gga5(x1, x2, x3, x4, x5)  =  if_append_3_in_1_gga2(x1, x5)
if_append3_4_in_2_ggga6(x1, x2, x3, x4, x5, x6)  =  if_append3_4_in_2_ggga1(x6)
append3_4_out_ggga4(x1, x2, x3, x4)  =  append3_4_out_ggga1(x4)
APPEND_3_IN_GGA3(x1, x2, x3)  =  APPEND_3_IN_GGA2(x1, x2)

We have to consider all (P,R,Pi)-chains
For (infinitary) constructor rewriting 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:

APPEND_3_IN_GGA3(._22(H, L1), L2, ._22(H, L3)) -> APPEND_3_IN_GGA3(L1, L2, L3)

R is empty.
The argument filtering Pi contains the following mapping:
._22(x1, x2)  =  ._22(x1, x2)
APPEND_3_IN_GGA3(x1, x2, x3)  =  APPEND_3_IN_GGA2(x1, x2)

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

↳ PROLOG
  ↳ PrologToPiTRSProof
    ↳ PiTRS
      ↳ DependencyPairsProof
        ↳ PiDP
          ↳ DependencyGraphProof
            ↳ PiDP
              ↳ UsableRulesProof
                ↳ PiDP
                  ↳ PiDPToQDPProof
QDP
                      ↳ QDPSizeChangeProof

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

APPEND_3_IN_GGA2(._22(H, L1), L2) -> APPEND_3_IN_GGA2(L1, L2)

R is empty.
Q is empty.
We have to consider all (P,Q,R)-chains.
The head symbols of this DP problem are {APPEND_3_IN_GGA2}.
By using the subterm criterion together with the size-change analysis 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: