(0) Obligation:
Q restricted rewrite system:
The TRS R consists of the following rules:
b(a(x)) → a(a(d(x)))
a(c(x)) → b(b(x))
d(a(b(x))) → b(d(d(c(x))))
d(x) → a(x)
b(a(c(a(x)))) → x
Q is empty.
 
(1) QTRS Reverse (EQUIVALENT transformation)
We applied the QTRS Reverse Processor [REVERSE].
(2) Obligation:
Q restricted rewrite system:
The TRS R consists of the following rules:
a(b(x)) → d(a(a(x)))
c(a(x)) → b(b(x))
b(a(d(x))) → c(d(d(b(x))))
d(x) → a(x)
a(c(a(b(x)))) → x
Q is empty.
 
(3) DependencyPairsProof (EQUIVALENT transformation)
Using Dependency Pairs [AG00,LPAR04] we result in the following initial DP problem.
(4) Obligation:
Q DP problem:
The TRS P consists of the following rules:
A(b(x)) → D(a(a(x)))
A(b(x)) → A(a(x))
A(b(x)) → A(x)
C(a(x)) → B(b(x))
C(a(x)) → B(x)
B(a(d(x))) → C(d(d(b(x))))
B(a(d(x))) → D(d(b(x)))
B(a(d(x))) → D(b(x))
B(a(d(x))) → B(x)
D(x) → A(x)
The TRS R consists of the following rules:
a(b(x)) → d(a(a(x)))
c(a(x)) → b(b(x))
b(a(d(x))) → c(d(d(b(x))))
d(x) → a(x)
a(c(a(b(x)))) → x
Q is empty.
We have to consider all minimal (P,Q,R)-chains.
 
(5) DependencyGraphProof (EQUIVALENT transformation)
The approximation of the Dependency Graph [LPAR04,FROCOS05,EDGSTAR] contains 2 SCCs with 2 less nodes.
(6) Complex Obligation (AND)
(7) Obligation:
Q DP problem:
The TRS P consists of the following rules:
D(x) → A(x)
A(b(x)) → D(a(a(x)))
A(b(x)) → A(a(x))
A(b(x)) → A(x)
The TRS R consists of the following rules:
a(b(x)) → d(a(a(x)))
c(a(x)) → b(b(x))
b(a(d(x))) → c(d(d(b(x))))
d(x) → a(x)
a(c(a(b(x)))) → x
Q is empty.
We have to consider all minimal (P,Q,R)-chains.
 
(8) UsableRulesProof (EQUIVALENT transformation)
We can use the usable rules and reduction pair processor [LPAR04] with the Ce-compatible extension of the polynomial order that maps every function symbol to the sum of its arguments. Then, we can delete all non-usable rules [FROCOS05] from R.
(9) Obligation:
Q DP problem:
The TRS P consists of the following rules:
D(x) → A(x)
A(b(x)) → D(a(a(x)))
A(b(x)) → A(a(x))
A(b(x)) → A(x)
The TRS R consists of the following rules:
d(x) → a(x)
a(b(x)) → d(a(a(x)))
a(c(a(b(x)))) → x
Q is empty.
We have to consider all minimal (P,Q,R)-chains.
 
(10) MRRProof (EQUIVALENT transformation)
By using the rule removal processor [LPAR04] with the following ordering, at least one Dependency Pair or term rewrite system rule of this QDP problem can be strictly oriented.
Strictly oriented dependency pairs:
A(b(x)) → D(a(a(x)))
A(b(x)) → A(a(x))
A(b(x)) → A(x)
Strictly oriented rules of the TRS R:
a(b(x)) → d(a(a(x)))
a(c(a(b(x)))) → x
Used ordering: Polynomial interpretation [POLO]:
POL(A(x1)) = 3·x1   
POL(D(x1)) = 3·x1   
POL(a(x1)) = x1   
POL(b(x1)) = 2 + 3·x1   
POL(c(x1)) = 3 + 3·x1   
POL(d(x1)) = x1   
 
(11) Obligation:
Q DP problem:
The TRS P consists of the following rules:
D(x) → A(x)
The TRS R consists of the following rules:
d(x) → a(x)
Q is empty.
We have to consider all minimal (P,Q,R)-chains.
 
(12) DependencyGraphProof (EQUIVALENT transformation)
The approximation of the Dependency Graph [LPAR04,FROCOS05,EDGSTAR] contains 0 SCCs with 1 less node.
(13) TRUE
(14) Obligation:
Q DP problem:
The TRS P consists of the following rules:
B(a(d(x))) → C(d(d(b(x))))
C(a(x)) → B(b(x))
B(a(d(x))) → B(x)
C(a(x)) → B(x)
The TRS R consists of the following rules:
a(b(x)) → d(a(a(x)))
c(a(x)) → b(b(x))
b(a(d(x))) → c(d(d(b(x))))
d(x) → a(x)
a(c(a(b(x)))) → x
Q is empty.
We have to consider all minimal (P,Q,R)-chains.
 
(15) QDPOrderProof (EQUIVALENT transformation)
We use the reduction pair processor [LPAR04,JAR06].
The following pairs can be oriented strictly and are deleted.
C(a(x)) → B(b(x))
The remaining pairs can at least be oriented weakly.
Used ordering:  Matrix interpretation [MATRO] with arctic natural numbers [ARCTIC]:
| POL(a(x1)) =  |  |  +  | | / | 0A | -I | -I | \ |  
| | | 0A | 0A | 0A | | |  
| \ | 0A | 0A | 0A | / |  
  | · | x1 | 
| POL(d(x1)) =  |  |  +  | | / | 0A | 0A | -I | \ |  
| | | 0A | 0A | 0A | | |  
| \ | 0A | 0A | 0A | / |  
  | · | x1 | 
| POL(b(x1)) =  |  |  +  | | / | 0A | 0A | 0A | \ |  
| | | 0A | 0A | 0A | | |  
| \ | -I | -I | -I | / |  
  | · | x1 | 
| POL(c(x1)) =  |  |  +  | | / | -I | -I | 0A | \ |  
| | | 0A | -I | 0A | | |  
| \ | -I | -I | -I | / |  
  | · | x1 | 
The following usable rules [FROCOS05] with respect to the argument filtering of the ordering [JAR06] were oriented:
b(a(d(x))) → c(d(d(b(x))))
c(a(x)) → b(b(x))
d(x) → a(x)
a(b(x)) → d(a(a(x)))
a(c(a(b(x)))) → x
 
(16) Obligation:
Q DP problem:
The TRS P consists of the following rules:
B(a(d(x))) → C(d(d(b(x))))
B(a(d(x))) → B(x)
C(a(x)) → B(x)
The TRS R consists of the following rules:
a(b(x)) → d(a(a(x)))
c(a(x)) → b(b(x))
b(a(d(x))) → c(d(d(b(x))))
d(x) → a(x)
a(c(a(b(x)))) → x
Q is empty.
We have to consider all minimal (P,Q,R)-chains.
 
(17) QDPOrderProof (EQUIVALENT transformation)
We use the reduction pair processor [LPAR04,JAR06].
The following pairs can be oriented strictly and are deleted.
C(a(x)) → B(x)
The remaining pairs can at least be oriented weakly.
Used ordering:  Matrix interpretation [MATRO] with arctic integers [ARCTIC,STERNAGEL_THIEMANN_RTA14]:
| POL(a(x1)) =  |  |  +  | | / | -I | 1A | -1A | \ |  
| | | -I | -1A | -1A | | |  
| \ | -1A | -1A | -1A | / |  
  | · | x1 | 
| POL(d(x1)) =  |  |  +  | | / | -I | 1A | -1A | \ |  
| | | -1A | -1A | -1A | | |  
| \ | -1A | -1A | -1A | / |  
  | · | x1 | 
| POL(b(x1)) =  |  |  +  | | / | -1A | -1A | -I | \ |  
| | | -I | -I | -I | | |  
| \ | 0A | 0A | 0A | / |  
  | · | x1 | 
| POL(c(x1)) =  |  |  +  | | / | -1A | -1A | -1A | \ |  
| | | -I | -I | -I | | |  
| \ | -1A | -1A | 2A | / |  
  | · | x1 | 
The following usable rules [FROCOS05] with respect to the argument filtering of the ordering [JAR06] were oriented:
b(a(d(x))) → c(d(d(b(x))))
c(a(x)) → b(b(x))
d(x) → a(x)
a(b(x)) → d(a(a(x)))
a(c(a(b(x)))) → x
 
(18) Obligation:
Q DP problem:
The TRS P consists of the following rules:
B(a(d(x))) → C(d(d(b(x))))
B(a(d(x))) → B(x)
The TRS R consists of the following rules:
a(b(x)) → d(a(a(x)))
c(a(x)) → b(b(x))
b(a(d(x))) → c(d(d(b(x))))
d(x) → a(x)
a(c(a(b(x)))) → x
Q is empty.
We have to consider all minimal (P,Q,R)-chains.
 
(19) DependencyGraphProof (EQUIVALENT transformation)
The approximation of the Dependency Graph [LPAR04,FROCOS05,EDGSTAR] contains 1 SCC with 1 less node.
(20) Obligation:
Q DP problem:
The TRS P consists of the following rules:
B(a(d(x))) → B(x)
The TRS R consists of the following rules:
a(b(x)) → d(a(a(x)))
c(a(x)) → b(b(x))
b(a(d(x))) → c(d(d(b(x))))
d(x) → a(x)
a(c(a(b(x)))) → x
Q is empty.
We have to consider all minimal (P,Q,R)-chains.
 
(21) UsableRulesProof (EQUIVALENT transformation)
We can use the usable rules and reduction pair processor [LPAR04] with the Ce-compatible extension of the polynomial order that maps every function symbol to the sum of its arguments. Then, we can delete all non-usable rules [FROCOS05] from R.
(22) Obligation:
Q DP problem:
The TRS P consists of the following rules:
B(a(d(x))) → B(x)
R is empty.
Q is empty.
We have to consider all minimal (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:
- B(a(d(x))) → B(x)
The graph contains the following edges 1 > 1 
 
(24) YES