(0) Obligation:

Clauses:

preorder(X, Y) :- pdl(X, -(Y, [])).
pdl(nil, Y) :- ','(!, eq(Y, -(X, X))).
pdl(T, -(.(X, Xs), Zs)) :- ','(value(T, X), ','(left(T, L), ','(right(T, R), ','(pdl(L, -(Xs, Ys)), pdl(R, -(Ys, Zs)))))).
left(nil, nil).
left(tree(L, X1, X2), L).
right(nil, nil).
right(tree(X3, X4, R), R).
value(nil, X5).
value(tree(X6, X, X7), X).
eq(X, X).

Query: preorder(g,a)

(1) PrologToDTProblemTransformerProof (SOUND transformation)

Built DT problem from termination graph DT10.

(2) Obligation:

Triples:

pdlA(tree(X1, X2, X3), .(X2, X4)) :- pdlB(X1, X4, X5).
pdlA(tree(X1, X2, X3), .(X2, X4)) :- ','(pdlcB(X1, X4, X5), pdlA(X3, X5)).
pdlB(tree(X1, X2, X3), .(X2, X4), X5) :- pdlB(X1, X4, X6).
pdlB(tree(X1, X2, X3), .(X2, X4), X5) :- ','(pdlcB(X1, X4, X6), pdlB(X3, X6, X5)).
preorderC(X1, X2) :- pdlA(X1, X2).

Clauses:

pdlcA(nil, []).
pdlcA(tree(X1, X2, X3), .(X2, X4)) :- ','(pdlcB(X1, X4, X5), pdlcA(X3, X5)).
pdlcB(nil, X1, X1).
pdlcB(tree(X1, X2, X3), .(X2, X4), X5) :- ','(pdlcB(X1, X4, X6), pdlcB(X3, X6, X5)).

Afs:

preorderC(x1, x2)  =  preorderC(x1)

(3) TriplesToPiDPProof (SOUND transformation)

We use the technique of [DT09]. With regard to the inferred argument filtering the predicates were used in the following modes:
preorderC_in: (b,f)
pdlA_in: (b,f)
pdlB_in: (b,f,f)
pdlcB_in: (b,f,f)
Transforming TRIPLES into the following Term Rewriting System:
Pi DP problem:
The TRS P consists of the following rules:

PREORDERC_IN_GA(X1, X2) → U7_GA(X1, X2, pdlA_in_ga(X1, X2))
PREORDERC_IN_GA(X1, X2) → PDLA_IN_GA(X1, X2)
PDLA_IN_GA(tree(X1, X2, X3), .(X2, X4)) → U1_GA(X1, X2, X3, X4, pdlB_in_gaa(X1, X4, X5))
PDLA_IN_GA(tree(X1, X2, X3), .(X2, X4)) → PDLB_IN_GAA(X1, X4, X5)
PDLB_IN_GAA(tree(X1, X2, X3), .(X2, X4), X5) → U4_GAA(X1, X2, X3, X4, X5, pdlB_in_gaa(X1, X4, X6))
PDLB_IN_GAA(tree(X1, X2, X3), .(X2, X4), X5) → PDLB_IN_GAA(X1, X4, X6)
PDLB_IN_GAA(tree(X1, X2, X3), .(X2, X4), X5) → U5_GAA(X1, X2, X3, X4, X5, pdlcB_in_gaa(X1, X4, X6))
U5_GAA(X1, X2, X3, X4, X5, pdlcB_out_gaa(X1, X4, X6)) → U6_GAA(X1, X2, X3, X4, X5, pdlB_in_gaa(X3, X6, X5))
U5_GAA(X1, X2, X3, X4, X5, pdlcB_out_gaa(X1, X4, X6)) → PDLB_IN_GAA(X3, X6, X5)
PDLA_IN_GA(tree(X1, X2, X3), .(X2, X4)) → U2_GA(X1, X2, X3, X4, pdlcB_in_gaa(X1, X4, X5))
U2_GA(X1, X2, X3, X4, pdlcB_out_gaa(X1, X4, X5)) → U3_GA(X1, X2, X3, X4, pdlA_in_ga(X3, X5))
U2_GA(X1, X2, X3, X4, pdlcB_out_gaa(X1, X4, X5)) → PDLA_IN_GA(X3, X5)

The TRS R consists of the following rules:

pdlcB_in_gaa(nil, X1, X1) → pdlcB_out_gaa(nil, X1, X1)
pdlcB_in_gaa(tree(X1, X2, X3), .(X2, X4), X5) → U11_gaa(X1, X2, X3, X4, X5, pdlcB_in_gaa(X1, X4, X6))
U11_gaa(X1, X2, X3, X4, X5, pdlcB_out_gaa(X1, X4, X6)) → U12_gaa(X1, X2, X3, X4, X5, X6, pdlcB_in_gaa(X3, X6, X5))
U12_gaa(X1, X2, X3, X4, X5, X6, pdlcB_out_gaa(X3, X6, X5)) → pdlcB_out_gaa(tree(X1, X2, X3), .(X2, X4), X5)

The argument filtering Pi contains the following mapping:
pdlA_in_ga(x1, x2)  =  pdlA_in_ga(x1)
tree(x1, x2, x3)  =  tree(x1, x2, x3)
pdlB_in_gaa(x1, x2, x3)  =  pdlB_in_gaa(x1)
pdlcB_in_gaa(x1, x2, x3)  =  pdlcB_in_gaa(x1)
nil  =  nil
pdlcB_out_gaa(x1, x2, x3)  =  pdlcB_out_gaa(x1)
U11_gaa(x1, x2, x3, x4, x5, x6)  =  U11_gaa(x1, x2, x3, x6)
U12_gaa(x1, x2, x3, x4, x5, x6, x7)  =  U12_gaa(x1, x2, x3, x7)
PREORDERC_IN_GA(x1, x2)  =  PREORDERC_IN_GA(x1)
U7_GA(x1, x2, x3)  =  U7_GA(x1, x3)
PDLA_IN_GA(x1, x2)  =  PDLA_IN_GA(x1)
U1_GA(x1, x2, x3, x4, x5)  =  U1_GA(x1, x2, x3, x5)
PDLB_IN_GAA(x1, x2, x3)  =  PDLB_IN_GAA(x1)
U4_GAA(x1, x2, x3, x4, x5, x6)  =  U4_GAA(x1, x2, x3, x6)
U5_GAA(x1, x2, x3, x4, x5, x6)  =  U5_GAA(x1, x2, x3, x6)
U6_GAA(x1, x2, x3, x4, x5, x6)  =  U6_GAA(x1, x2, x3, x6)
U2_GA(x1, x2, x3, x4, x5)  =  U2_GA(x1, x2, x3, x5)
U3_GA(x1, x2, x3, x4, x5)  =  U3_GA(x1, x2, x3, x5)

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

Infinitary Constructor Rewriting Termination of PiDP implies Termination of TRIPLES

(4) Obligation:

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

PREORDERC_IN_GA(X1, X2) → U7_GA(X1, X2, pdlA_in_ga(X1, X2))
PREORDERC_IN_GA(X1, X2) → PDLA_IN_GA(X1, X2)
PDLA_IN_GA(tree(X1, X2, X3), .(X2, X4)) → U1_GA(X1, X2, X3, X4, pdlB_in_gaa(X1, X4, X5))
PDLA_IN_GA(tree(X1, X2, X3), .(X2, X4)) → PDLB_IN_GAA(X1, X4, X5)
PDLB_IN_GAA(tree(X1, X2, X3), .(X2, X4), X5) → U4_GAA(X1, X2, X3, X4, X5, pdlB_in_gaa(X1, X4, X6))
PDLB_IN_GAA(tree(X1, X2, X3), .(X2, X4), X5) → PDLB_IN_GAA(X1, X4, X6)
PDLB_IN_GAA(tree(X1, X2, X3), .(X2, X4), X5) → U5_GAA(X1, X2, X3, X4, X5, pdlcB_in_gaa(X1, X4, X6))
U5_GAA(X1, X2, X3, X4, X5, pdlcB_out_gaa(X1, X4, X6)) → U6_GAA(X1, X2, X3, X4, X5, pdlB_in_gaa(X3, X6, X5))
U5_GAA(X1, X2, X3, X4, X5, pdlcB_out_gaa(X1, X4, X6)) → PDLB_IN_GAA(X3, X6, X5)
PDLA_IN_GA(tree(X1, X2, X3), .(X2, X4)) → U2_GA(X1, X2, X3, X4, pdlcB_in_gaa(X1, X4, X5))
U2_GA(X1, X2, X3, X4, pdlcB_out_gaa(X1, X4, X5)) → U3_GA(X1, X2, X3, X4, pdlA_in_ga(X3, X5))
U2_GA(X1, X2, X3, X4, pdlcB_out_gaa(X1, X4, X5)) → PDLA_IN_GA(X3, X5)

The TRS R consists of the following rules:

pdlcB_in_gaa(nil, X1, X1) → pdlcB_out_gaa(nil, X1, X1)
pdlcB_in_gaa(tree(X1, X2, X3), .(X2, X4), X5) → U11_gaa(X1, X2, X3, X4, X5, pdlcB_in_gaa(X1, X4, X6))
U11_gaa(X1, X2, X3, X4, X5, pdlcB_out_gaa(X1, X4, X6)) → U12_gaa(X1, X2, X3, X4, X5, X6, pdlcB_in_gaa(X3, X6, X5))
U12_gaa(X1, X2, X3, X4, X5, X6, pdlcB_out_gaa(X3, X6, X5)) → pdlcB_out_gaa(tree(X1, X2, X3), .(X2, X4), X5)

The argument filtering Pi contains the following mapping:
pdlA_in_ga(x1, x2)  =  pdlA_in_ga(x1)
tree(x1, x2, x3)  =  tree(x1, x2, x3)
pdlB_in_gaa(x1, x2, x3)  =  pdlB_in_gaa(x1)
pdlcB_in_gaa(x1, x2, x3)  =  pdlcB_in_gaa(x1)
nil  =  nil
pdlcB_out_gaa(x1, x2, x3)  =  pdlcB_out_gaa(x1)
U11_gaa(x1, x2, x3, x4, x5, x6)  =  U11_gaa(x1, x2, x3, x6)
U12_gaa(x1, x2, x3, x4, x5, x6, x7)  =  U12_gaa(x1, x2, x3, x7)
PREORDERC_IN_GA(x1, x2)  =  PREORDERC_IN_GA(x1)
U7_GA(x1, x2, x3)  =  U7_GA(x1, x3)
PDLA_IN_GA(x1, x2)  =  PDLA_IN_GA(x1)
U1_GA(x1, x2, x3, x4, x5)  =  U1_GA(x1, x2, x3, x5)
PDLB_IN_GAA(x1, x2, x3)  =  PDLB_IN_GAA(x1)
U4_GAA(x1, x2, x3, x4, x5, x6)  =  U4_GAA(x1, x2, x3, x6)
U5_GAA(x1, x2, x3, x4, x5, x6)  =  U5_GAA(x1, x2, x3, x6)
U6_GAA(x1, x2, x3, x4, x5, x6)  =  U6_GAA(x1, x2, x3, x6)
U2_GA(x1, x2, x3, x4, x5)  =  U2_GA(x1, x2, x3, x5)
U3_GA(x1, x2, x3, x4, x5)  =  U3_GA(x1, x2, x3, x5)

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

(5) DependencyGraphProof (EQUIVALENT transformation)

The approximation of the Dependency Graph [LOPSTR] contains 2 SCCs with 7 less nodes.

(6) Complex Obligation (AND)

(7) Obligation:

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

PDLB_IN_GAA(tree(X1, X2, X3), .(X2, X4), X5) → U5_GAA(X1, X2, X3, X4, X5, pdlcB_in_gaa(X1, X4, X6))
U5_GAA(X1, X2, X3, X4, X5, pdlcB_out_gaa(X1, X4, X6)) → PDLB_IN_GAA(X3, X6, X5)
PDLB_IN_GAA(tree(X1, X2, X3), .(X2, X4), X5) → PDLB_IN_GAA(X1, X4, X6)

The TRS R consists of the following rules:

pdlcB_in_gaa(nil, X1, X1) → pdlcB_out_gaa(nil, X1, X1)
pdlcB_in_gaa(tree(X1, X2, X3), .(X2, X4), X5) → U11_gaa(X1, X2, X3, X4, X5, pdlcB_in_gaa(X1, X4, X6))
U11_gaa(X1, X2, X3, X4, X5, pdlcB_out_gaa(X1, X4, X6)) → U12_gaa(X1, X2, X3, X4, X5, X6, pdlcB_in_gaa(X3, X6, X5))
U12_gaa(X1, X2, X3, X4, X5, X6, pdlcB_out_gaa(X3, X6, X5)) → pdlcB_out_gaa(tree(X1, X2, X3), .(X2, X4), X5)

The argument filtering Pi contains the following mapping:
tree(x1, x2, x3)  =  tree(x1, x2, x3)
pdlcB_in_gaa(x1, x2, x3)  =  pdlcB_in_gaa(x1)
nil  =  nil
pdlcB_out_gaa(x1, x2, x3)  =  pdlcB_out_gaa(x1)
U11_gaa(x1, x2, x3, x4, x5, x6)  =  U11_gaa(x1, x2, x3, x6)
U12_gaa(x1, x2, x3, x4, x5, x6, x7)  =  U12_gaa(x1, x2, x3, x7)
PDLB_IN_GAA(x1, x2, x3)  =  PDLB_IN_GAA(x1)
U5_GAA(x1, x2, x3, x4, x5, x6)  =  U5_GAA(x1, x2, x3, x6)

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

(8) PiDPToQDPProof (SOUND transformation)

Transforming (infinitary) constructor rewriting Pi-DP problem [LOPSTR] into ordinary QDP problem [LPAR04] by application of Pi.

(9) Obligation:

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

PDLB_IN_GAA(tree(X1, X2, X3)) → U5_GAA(X1, X2, X3, pdlcB_in_gaa(X1))
U5_GAA(X1, X2, X3, pdlcB_out_gaa(X1)) → PDLB_IN_GAA(X3)
PDLB_IN_GAA(tree(X1, X2, X3)) → PDLB_IN_GAA(X1)

The TRS R consists of the following rules:

pdlcB_in_gaa(nil) → pdlcB_out_gaa(nil)
pdlcB_in_gaa(tree(X1, X2, X3)) → U11_gaa(X1, X2, X3, pdlcB_in_gaa(X1))
U11_gaa(X1, X2, X3, pdlcB_out_gaa(X1)) → U12_gaa(X1, X2, X3, pdlcB_in_gaa(X3))
U12_gaa(X1, X2, X3, pdlcB_out_gaa(X3)) → pdlcB_out_gaa(tree(X1, X2, X3))

The set Q consists of the following terms:

pdlcB_in_gaa(x0)
U11_gaa(x0, x1, x2, x3)
U12_gaa(x0, x1, x2, x3)

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

(10) QDPSizeChangeProof (EQUIVALENT transformation)

By using the subterm criterion [SUBTERM_CRITERION] together with the size-change analysis [AAECC05] 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:

  • U5_GAA(X1, X2, X3, pdlcB_out_gaa(X1)) → PDLB_IN_GAA(X3)
    The graph contains the following edges 3 >= 1

  • PDLB_IN_GAA(tree(X1, X2, X3)) → PDLB_IN_GAA(X1)
    The graph contains the following edges 1 > 1

  • PDLB_IN_GAA(tree(X1, X2, X3)) → U5_GAA(X1, X2, X3, pdlcB_in_gaa(X1))
    The graph contains the following edges 1 > 1, 1 > 2, 1 > 3

(11) YES

(12) Obligation:

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

PDLA_IN_GA(tree(X1, X2, X3), .(X2, X4)) → U2_GA(X1, X2, X3, X4, pdlcB_in_gaa(X1, X4, X5))
U2_GA(X1, X2, X3, X4, pdlcB_out_gaa(X1, X4, X5)) → PDLA_IN_GA(X3, X5)

The TRS R consists of the following rules:

pdlcB_in_gaa(nil, X1, X1) → pdlcB_out_gaa(nil, X1, X1)
pdlcB_in_gaa(tree(X1, X2, X3), .(X2, X4), X5) → U11_gaa(X1, X2, X3, X4, X5, pdlcB_in_gaa(X1, X4, X6))
U11_gaa(X1, X2, X3, X4, X5, pdlcB_out_gaa(X1, X4, X6)) → U12_gaa(X1, X2, X3, X4, X5, X6, pdlcB_in_gaa(X3, X6, X5))
U12_gaa(X1, X2, X3, X4, X5, X6, pdlcB_out_gaa(X3, X6, X5)) → pdlcB_out_gaa(tree(X1, X2, X3), .(X2, X4), X5)

The argument filtering Pi contains the following mapping:
tree(x1, x2, x3)  =  tree(x1, x2, x3)
pdlcB_in_gaa(x1, x2, x3)  =  pdlcB_in_gaa(x1)
nil  =  nil
pdlcB_out_gaa(x1, x2, x3)  =  pdlcB_out_gaa(x1)
U11_gaa(x1, x2, x3, x4, x5, x6)  =  U11_gaa(x1, x2, x3, x6)
U12_gaa(x1, x2, x3, x4, x5, x6, x7)  =  U12_gaa(x1, x2, x3, x7)
PDLA_IN_GA(x1, x2)  =  PDLA_IN_GA(x1)
U2_GA(x1, x2, x3, x4, x5)  =  U2_GA(x1, x2, x3, x5)

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

(13) PiDPToQDPProof (SOUND transformation)

Transforming (infinitary) constructor rewriting Pi-DP problem [LOPSTR] into ordinary QDP problem [LPAR04] by application of Pi.

(14) Obligation:

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

PDLA_IN_GA(tree(X1, X2, X3)) → U2_GA(X1, X2, X3, pdlcB_in_gaa(X1))
U2_GA(X1, X2, X3, pdlcB_out_gaa(X1)) → PDLA_IN_GA(X3)

The TRS R consists of the following rules:

pdlcB_in_gaa(nil) → pdlcB_out_gaa(nil)
pdlcB_in_gaa(tree(X1, X2, X3)) → U11_gaa(X1, X2, X3, pdlcB_in_gaa(X1))
U11_gaa(X1, X2, X3, pdlcB_out_gaa(X1)) → U12_gaa(X1, X2, X3, pdlcB_in_gaa(X3))
U12_gaa(X1, X2, X3, pdlcB_out_gaa(X3)) → pdlcB_out_gaa(tree(X1, X2, X3))

The set Q consists of the following terms:

pdlcB_in_gaa(x0)
U11_gaa(x0, x1, x2, x3)
U12_gaa(x0, x1, x2, x3)

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

(15) QDPSizeChangeProof (EQUIVALENT transformation)

By using the subterm criterion [SUBTERM_CRITERION] together with the size-change analysis [AAECC05] 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:

  • U2_GA(X1, X2, X3, pdlcB_out_gaa(X1)) → PDLA_IN_GA(X3)
    The graph contains the following edges 3 >= 1

  • PDLA_IN_GA(tree(X1, X2, X3)) → U2_GA(X1, X2, X3, pdlcB_in_gaa(X1))
    The graph contains the following edges 1 > 1, 1 > 2, 1 > 3

(16) YES