Termination of the given ITRSProblem could successfully be proven:



ITRS
  ↳ ITRStoIDPProof

ITRS problem:
The following domains are used:

z

The TRS R consists of the following rules:

if1(TRUE, x, y) → h(x, y)
h(x, y) → if2(>@z(x, y), x, y)
if2(FALSE, x, y) → f(x, y)
if2(TRUE, x, y) → 0@z
if1(FALSE, x, y) → 0@z
f(x, y) → if1(>@z(x, y), x, y)

The set Q consists of the following terms:

if1(TRUE, x0, x1)
h(x0, x1)
if2(FALSE, x0, x1)
if2(TRUE, x0, x1)
if1(FALSE, x0, x1)
f(x0, x1)


Added dependency pairs

↳ ITRS
  ↳ ITRStoIDPProof
IDP
      ↳ UsableRulesProof

I DP problem:
The following domains are used:

z

The ITRS R consists of the following rules:

if1(TRUE, x, y) → h(x, y)
h(x, y) → if2(>@z(x, y), x, y)
if2(FALSE, x, y) → f(x, y)
if2(TRUE, x, y) → 0@z
if1(FALSE, x, y) → 0@z
f(x, y) → if1(>@z(x, y), x, y)

The integer pair graph contains the following rules and edges:

(0): F(x[0], y[0]) → IF1(>@z(x[0], y[0]), x[0], y[0])
(1): IF2(FALSE, x[1], y[1]) → F(x[1], y[1])
(2): IF1(TRUE, x[2], y[2]) → H(x[2], y[2])
(3): H(x[3], y[3]) → IF2(>@z(x[3], y[3]), x[3], y[3])

(0) -> (2), if ((x[0]* x[2])∧(y[0]* y[2])∧(>@z(x[0], y[0]) →* TRUE))


(1) -> (0), if ((y[1]* y[0])∧(x[1]* x[0]))


(2) -> (3), if ((y[2]* y[3])∧(x[2]* x[3]))


(3) -> (1), if ((x[3]* x[1])∧(y[3]* y[1])∧(>@z(x[3], y[3]) →* FALSE))



The set Q consists of the following terms:

if1(TRUE, x0, x1)
h(x0, x1)
if2(FALSE, x0, x1)
if2(TRUE, x0, x1)
if1(FALSE, x0, x1)
f(x0, x1)


As all Q-normal forms are R-normal forms we are in the innermost case. Hence, by the usable rules processor [LPAR04] we can delete all non-usable rules [FROCOS05] from R.

↳ ITRS
  ↳ ITRStoIDPProof
    ↳ IDP
      ↳ UsableRulesProof
IDP
          ↳ IDPNonInfProof

I DP problem:
The following domains are used:

z

R is empty.
The integer pair graph contains the following rules and edges:

(0): F(x[0], y[0]) → IF1(>@z(x[0], y[0]), x[0], y[0])
(1): IF2(FALSE, x[1], y[1]) → F(x[1], y[1])
(2): IF1(TRUE, x[2], y[2]) → H(x[2], y[2])
(3): H(x[3], y[3]) → IF2(>@z(x[3], y[3]), x[3], y[3])

(0) -> (2), if ((x[0]* x[2])∧(y[0]* y[2])∧(>@z(x[0], y[0]) →* TRUE))


(1) -> (0), if ((y[1]* y[0])∧(x[1]* x[0]))


(2) -> (3), if ((y[2]* y[3])∧(x[2]* x[3]))


(3) -> (1), if ((x[3]* x[1])∧(y[3]* y[1])∧(>@z(x[3], y[3]) →* FALSE))



The set Q consists of the following terms:

if1(TRUE, x0, x1)
h(x0, x1)
if2(FALSE, x0, x1)
if2(TRUE, x0, x1)
if1(FALSE, x0, x1)
f(x0, x1)


The constraints were generated the following way:
The DP Problem is simplified using the Induction Calculus [NONINF] with the following steps:
Note that final constraints are written in bold face.


For Pair F(x, y) → IF1(>@z(x, y), x, y) the following chains were created:




For Pair IF2(FALSE, x, y) → F(x, y) the following chains were created:




For Pair IF1(TRUE, x, y) → H(x, y) the following chains were created:




For Pair H(x, y) → IF2(>@z(x, y), x, y) the following chains were created:




To summarize, we get the following constraints P for the following pairs.



The constraints for P> respective Pbound are constructed from P where we just replace every occurence of "t ≥ s" in P by "t > s" respective "t ≥ c". Here c stands for the fresh constant used for Pbound.
Using the following integer polynomial ordering the resulting constraints can be solved
Polynomial interpretation over integers[POLO]:

POL(IF2(x1, x2, x3)) = -1 + x3 + (-1)x2   
POL(TRUE) = -1   
POL(IF1(x1, x2, x3)) = -1 + (-1)x3 + x2   
POL(FALSE) = -1   
POL(F(x1, x2)) = -1 + (-1)x2 + x1   
POL(undefined) = -1   
POL(H(x1, x2)) = -1 + x2 + (-1)x1   
POL(>@z(x1, x2)) = -1   

The following pairs are in P>:

IF1(TRUE, x[2], y[2]) → H(x[2], y[2])

The following pairs are in Pbound:

IF2(FALSE, x[1], y[1]) → F(x[1], y[1])

The following pairs are in P:

F(x[0], y[0]) → IF1(>@z(x[0], y[0]), x[0], y[0])
IF2(FALSE, x[1], y[1]) → F(x[1], y[1])
H(x[3], y[3]) → IF2(>@z(x[3], y[3]), x[3], y[3])

There are no usable rules.

↳ ITRS
  ↳ ITRStoIDPProof
    ↳ IDP
      ↳ UsableRulesProof
        ↳ IDP
          ↳ IDPNonInfProof
            ↳ AND
IDP
                ↳ IDependencyGraphProof
              ↳ IDP

I DP problem:
The following domains are used:

z

R is empty.
The integer pair graph contains the following rules and edges:

(0): F(x[0], y[0]) → IF1(>@z(x[0], y[0]), x[0], y[0])
(2): IF1(TRUE, x[2], y[2]) → H(x[2], y[2])
(3): H(x[3], y[3]) → IF2(>@z(x[3], y[3]), x[3], y[3])

(2) -> (3), if ((y[2]* y[3])∧(x[2]* x[3]))


(0) -> (2), if ((x[0]* x[2])∧(y[0]* y[2])∧(>@z(x[0], y[0]) →* TRUE))



The set Q consists of the following terms:

if1(TRUE, x0, x1)
h(x0, x1)
if2(FALSE, x0, x1)
if2(TRUE, x0, x1)
if1(FALSE, x0, x1)
f(x0, x1)


The approximation of the Dependency Graph [LPAR04,FROCOS05,EDGSTAR] contains 0 SCCs with 3 less nodes.

↳ ITRS
  ↳ ITRStoIDPProof
    ↳ IDP
      ↳ UsableRulesProof
        ↳ IDP
          ↳ IDPNonInfProof
            ↳ AND
              ↳ IDP
IDP
                ↳ IDependencyGraphProof

I DP problem:
The following domains are used:

z

R is empty.
The integer pair graph contains the following rules and edges:

(0): F(x[0], y[0]) → IF1(>@z(x[0], y[0]), x[0], y[0])
(1): IF2(FALSE, x[1], y[1]) → F(x[1], y[1])
(3): H(x[3], y[3]) → IF2(>@z(x[3], y[3]), x[3], y[3])

(1) -> (0), if ((y[1]* y[0])∧(x[1]* x[0]))


(3) -> (1), if ((x[3]* x[1])∧(y[3]* y[1])∧(>@z(x[3], y[3]) →* FALSE))



The set Q consists of the following terms:

if1(TRUE, x0, x1)
h(x0, x1)
if2(FALSE, x0, x1)
if2(TRUE, x0, x1)
if1(FALSE, x0, x1)
f(x0, x1)


The approximation of the Dependency Graph [LPAR04,FROCOS05,EDGSTAR] contains 0 SCCs with 3 less nodes.