(0) Obligation:

Clauses:

less(0, Y) :- ','(!, =(Y, s(X2))).
less(X, Y) :- ','(p(X, X1), ','(p(Y, Y1), less(X1, Y1))).
p(0, 0).
p(s(X), X).
=(X, X).

Query: less(g,a)

(1) BuiltinConflictTransformerProof (EQUIVALENT transformation)

Renamed defined predicates conflicting with built-in predicates [PROLOG].

(2) Obligation:

Clauses:

less(0, Y) :- ','(!, user_defined_=(Y, s(X2))).
less(X, Y) :- ','(p(X, X1), ','(p(Y, Y1), less(X1, Y1))).
p(0, 0).
p(s(X), X).
user_defined_=(X, X).

Query: less(g,a)

(3) PrologToPrologProblemTransformerProof (SOUND transformation)

Built Prolog problem from termination graph ICLP10.

(4) Obligation:

Clauses:

lessA(s(T25)) :- lessA(T25).
lessB(0, s(T11)).
lessB(s(T19), 0) :- lessA(T19).
lessB(s(T19), s(T29)) :- lessB(T19, T29).

Query: lessB(g,a)

(5) PrologToPiTRSProof (SOUND transformation)

We use the technique of [TOCL09]. With regard to the inferred argument filtering the predicates were used in the following modes:
lessB_in: (b,f)
lessA_in: (b)
Transforming Prolog into the following Term Rewriting System:
Pi-finite rewrite system:
The TRS R consists of the following rules:

lessB_in_ga(0, s(T11)) → lessB_out_ga(0, s(T11))
lessB_in_ga(s(T19), 0) → U2_ga(T19, lessA_in_g(T19))
lessA_in_g(s(T25)) → U1_g(T25, lessA_in_g(T25))
U1_g(T25, lessA_out_g(T25)) → lessA_out_g(s(T25))
U2_ga(T19, lessA_out_g(T19)) → lessB_out_ga(s(T19), 0)
lessB_in_ga(s(T19), s(T29)) → U3_ga(T19, T29, lessB_in_ga(T19, T29))
U3_ga(T19, T29, lessB_out_ga(T19, T29)) → lessB_out_ga(s(T19), s(T29))

The argument filtering Pi contains the following mapping:
lessB_in_ga(x1, x2)  =  lessB_in_ga(x1)
0  =  0
lessB_out_ga(x1, x2)  =  lessB_out_ga
s(x1)  =  s(x1)
U2_ga(x1, x2)  =  U2_ga(x2)
lessA_in_g(x1)  =  lessA_in_g(x1)
U1_g(x1, x2)  =  U1_g(x2)
lessA_out_g(x1)  =  lessA_out_g
U3_ga(x1, x2, x3)  =  U3_ga(x3)

Infinitary Constructor Rewriting Termination of PiTRS implies Termination of Prolog

(6) Obligation:

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

lessB_in_ga(0, s(T11)) → lessB_out_ga(0, s(T11))
lessB_in_ga(s(T19), 0) → U2_ga(T19, lessA_in_g(T19))
lessA_in_g(s(T25)) → U1_g(T25, lessA_in_g(T25))
U1_g(T25, lessA_out_g(T25)) → lessA_out_g(s(T25))
U2_ga(T19, lessA_out_g(T19)) → lessB_out_ga(s(T19), 0)
lessB_in_ga(s(T19), s(T29)) → U3_ga(T19, T29, lessB_in_ga(T19, T29))
U3_ga(T19, T29, lessB_out_ga(T19, T29)) → lessB_out_ga(s(T19), s(T29))

The argument filtering Pi contains the following mapping:
lessB_in_ga(x1, x2)  =  lessB_in_ga(x1)
0  =  0
lessB_out_ga(x1, x2)  =  lessB_out_ga
s(x1)  =  s(x1)
U2_ga(x1, x2)  =  U2_ga(x2)
lessA_in_g(x1)  =  lessA_in_g(x1)
U1_g(x1, x2)  =  U1_g(x2)
lessA_out_g(x1)  =  lessA_out_g
U3_ga(x1, x2, x3)  =  U3_ga(x3)

(7) DependencyPairsProof (EQUIVALENT transformation)

Using Dependency Pairs [AG00,LOPSTR] we result in the following initial DP problem:
Pi DP problem:
The TRS P consists of the following rules:

LESSB_IN_GA(s(T19), 0) → U2_GA(T19, lessA_in_g(T19))
LESSB_IN_GA(s(T19), 0) → LESSA_IN_G(T19)
LESSA_IN_G(s(T25)) → U1_G(T25, lessA_in_g(T25))
LESSA_IN_G(s(T25)) → LESSA_IN_G(T25)
LESSB_IN_GA(s(T19), s(T29)) → U3_GA(T19, T29, lessB_in_ga(T19, T29))
LESSB_IN_GA(s(T19), s(T29)) → LESSB_IN_GA(T19, T29)

The TRS R consists of the following rules:

lessB_in_ga(0, s(T11)) → lessB_out_ga(0, s(T11))
lessB_in_ga(s(T19), 0) → U2_ga(T19, lessA_in_g(T19))
lessA_in_g(s(T25)) → U1_g(T25, lessA_in_g(T25))
U1_g(T25, lessA_out_g(T25)) → lessA_out_g(s(T25))
U2_ga(T19, lessA_out_g(T19)) → lessB_out_ga(s(T19), 0)
lessB_in_ga(s(T19), s(T29)) → U3_ga(T19, T29, lessB_in_ga(T19, T29))
U3_ga(T19, T29, lessB_out_ga(T19, T29)) → lessB_out_ga(s(T19), s(T29))

The argument filtering Pi contains the following mapping:
lessB_in_ga(x1, x2)  =  lessB_in_ga(x1)
0  =  0
lessB_out_ga(x1, x2)  =  lessB_out_ga
s(x1)  =  s(x1)
U2_ga(x1, x2)  =  U2_ga(x2)
lessA_in_g(x1)  =  lessA_in_g(x1)
U1_g(x1, x2)  =  U1_g(x2)
lessA_out_g(x1)  =  lessA_out_g
U3_ga(x1, x2, x3)  =  U3_ga(x3)
LESSB_IN_GA(x1, x2)  =  LESSB_IN_GA(x1)
U2_GA(x1, x2)  =  U2_GA(x2)
LESSA_IN_G(x1)  =  LESSA_IN_G(x1)
U1_G(x1, x2)  =  U1_G(x2)
U3_GA(x1, x2, x3)  =  U3_GA(x3)

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

(8) Obligation:

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

LESSB_IN_GA(s(T19), 0) → U2_GA(T19, lessA_in_g(T19))
LESSB_IN_GA(s(T19), 0) → LESSA_IN_G(T19)
LESSA_IN_G(s(T25)) → U1_G(T25, lessA_in_g(T25))
LESSA_IN_G(s(T25)) → LESSA_IN_G(T25)
LESSB_IN_GA(s(T19), s(T29)) → U3_GA(T19, T29, lessB_in_ga(T19, T29))
LESSB_IN_GA(s(T19), s(T29)) → LESSB_IN_GA(T19, T29)

The TRS R consists of the following rules:

lessB_in_ga(0, s(T11)) → lessB_out_ga(0, s(T11))
lessB_in_ga(s(T19), 0) → U2_ga(T19, lessA_in_g(T19))
lessA_in_g(s(T25)) → U1_g(T25, lessA_in_g(T25))
U1_g(T25, lessA_out_g(T25)) → lessA_out_g(s(T25))
U2_ga(T19, lessA_out_g(T19)) → lessB_out_ga(s(T19), 0)
lessB_in_ga(s(T19), s(T29)) → U3_ga(T19, T29, lessB_in_ga(T19, T29))
U3_ga(T19, T29, lessB_out_ga(T19, T29)) → lessB_out_ga(s(T19), s(T29))

The argument filtering Pi contains the following mapping:
lessB_in_ga(x1, x2)  =  lessB_in_ga(x1)
0  =  0
lessB_out_ga(x1, x2)  =  lessB_out_ga
s(x1)  =  s(x1)
U2_ga(x1, x2)  =  U2_ga(x2)
lessA_in_g(x1)  =  lessA_in_g(x1)
U1_g(x1, x2)  =  U1_g(x2)
lessA_out_g(x1)  =  lessA_out_g
U3_ga(x1, x2, x3)  =  U3_ga(x3)
LESSB_IN_GA(x1, x2)  =  LESSB_IN_GA(x1)
U2_GA(x1, x2)  =  U2_GA(x2)
LESSA_IN_G(x1)  =  LESSA_IN_G(x1)
U1_G(x1, x2)  =  U1_G(x2)
U3_GA(x1, x2, x3)  =  U3_GA(x3)

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

(9) DependencyGraphProof (EQUIVALENT transformation)

The approximation of the Dependency Graph [LOPSTR] contains 2 SCCs with 4 less nodes.

(10) Complex Obligation (AND)

(11) Obligation:

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

LESSA_IN_G(s(T25)) → LESSA_IN_G(T25)

The TRS R consists of the following rules:

lessB_in_ga(0, s(T11)) → lessB_out_ga(0, s(T11))
lessB_in_ga(s(T19), 0) → U2_ga(T19, lessA_in_g(T19))
lessA_in_g(s(T25)) → U1_g(T25, lessA_in_g(T25))
U1_g(T25, lessA_out_g(T25)) → lessA_out_g(s(T25))
U2_ga(T19, lessA_out_g(T19)) → lessB_out_ga(s(T19), 0)
lessB_in_ga(s(T19), s(T29)) → U3_ga(T19, T29, lessB_in_ga(T19, T29))
U3_ga(T19, T29, lessB_out_ga(T19, T29)) → lessB_out_ga(s(T19), s(T29))

The argument filtering Pi contains the following mapping:
lessB_in_ga(x1, x2)  =  lessB_in_ga(x1)
0  =  0
lessB_out_ga(x1, x2)  =  lessB_out_ga
s(x1)  =  s(x1)
U2_ga(x1, x2)  =  U2_ga(x2)
lessA_in_g(x1)  =  lessA_in_g(x1)
U1_g(x1, x2)  =  U1_g(x2)
lessA_out_g(x1)  =  lessA_out_g
U3_ga(x1, x2, x3)  =  U3_ga(x3)
LESSA_IN_G(x1)  =  LESSA_IN_G(x1)

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

(12) UsableRulesProof (EQUIVALENT transformation)

For (infinitary) constructor rewriting [LOPSTR] we can delete all non-usable rules from R.

(13) Obligation:

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

LESSA_IN_G(s(T25)) → LESSA_IN_G(T25)

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

(14) PiDPToQDPProof (EQUIVALENT transformation)

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

(15) Obligation:

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

LESSA_IN_G(s(T25)) → LESSA_IN_G(T25)

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

(16) 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:

  • LESSA_IN_G(s(T25)) → LESSA_IN_G(T25)
    The graph contains the following edges 1 > 1

(17) YES

(18) Obligation:

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

LESSB_IN_GA(s(T19), s(T29)) → LESSB_IN_GA(T19, T29)

The TRS R consists of the following rules:

lessB_in_ga(0, s(T11)) → lessB_out_ga(0, s(T11))
lessB_in_ga(s(T19), 0) → U2_ga(T19, lessA_in_g(T19))
lessA_in_g(s(T25)) → U1_g(T25, lessA_in_g(T25))
U1_g(T25, lessA_out_g(T25)) → lessA_out_g(s(T25))
U2_ga(T19, lessA_out_g(T19)) → lessB_out_ga(s(T19), 0)
lessB_in_ga(s(T19), s(T29)) → U3_ga(T19, T29, lessB_in_ga(T19, T29))
U3_ga(T19, T29, lessB_out_ga(T19, T29)) → lessB_out_ga(s(T19), s(T29))

The argument filtering Pi contains the following mapping:
lessB_in_ga(x1, x2)  =  lessB_in_ga(x1)
0  =  0
lessB_out_ga(x1, x2)  =  lessB_out_ga
s(x1)  =  s(x1)
U2_ga(x1, x2)  =  U2_ga(x2)
lessA_in_g(x1)  =  lessA_in_g(x1)
U1_g(x1, x2)  =  U1_g(x2)
lessA_out_g(x1)  =  lessA_out_g
U3_ga(x1, x2, x3)  =  U3_ga(x3)
LESSB_IN_GA(x1, x2)  =  LESSB_IN_GA(x1)

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

(19) UsableRulesProof (EQUIVALENT transformation)

For (infinitary) constructor rewriting [LOPSTR] we can delete all non-usable rules from R.

(20) Obligation:

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

LESSB_IN_GA(s(T19), s(T29)) → LESSB_IN_GA(T19, T29)

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

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

(21) PiDPToQDPProof (SOUND transformation)

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

(22) Obligation:

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

LESSB_IN_GA(s(T19)) → LESSB_IN_GA(T19)

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

(23) 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:

  • LESSB_IN_GA(s(T19)) → LESSB_IN_GA(T19)
    The graph contains the following edges 1 > 1

(24) YES