YES

Problem 1: 

(VAR v_NonEmpty:S x1:S)
(RULES
a(a(x1:S)) -> d(c(x1:S))
a(b(x1:S)) -> c(c(c(x1:S)))
b(b(x1:S)) -> a(c(c(x1:S)))
c(c(x1:S)) -> b(x1:S)
c(d(x1:S)) -> a(a(x1:S))
d(d(x1:S)) -> b(a(c(x1:S)))
)

Problem 1: 

Dependency Pairs Processor:
-> Pairs:
 A(a(x1:S)) -> C(x1:S)
 A(a(x1:S)) -> D(c(x1:S))
 A(b(x1:S)) -> C(c(c(x1:S)))
 A(b(x1:S)) -> C(c(x1:S))
 A(b(x1:S)) -> C(x1:S)
 B(b(x1:S)) -> A(c(c(x1:S)))
 B(b(x1:S)) -> C(c(x1:S))
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
 C(d(x1:S)) -> A(a(x1:S))
 C(d(x1:S)) -> A(x1:S)
 D(d(x1:S)) -> A(c(x1:S))
 D(d(x1:S)) -> B(a(c(x1:S)))
 D(d(x1:S)) -> C(x1:S)
-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))

Problem 1: 

SCC Processor:
-> Pairs:
 A(a(x1:S)) -> C(x1:S)
 A(a(x1:S)) -> D(c(x1:S))
 A(b(x1:S)) -> C(c(c(x1:S)))
 A(b(x1:S)) -> C(c(x1:S))
 A(b(x1:S)) -> C(x1:S)
 B(b(x1:S)) -> A(c(c(x1:S)))
 B(b(x1:S)) -> C(c(x1:S))
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
 C(d(x1:S)) -> A(a(x1:S))
 C(d(x1:S)) -> A(x1:S)
 D(d(x1:S)) -> A(c(x1:S))
 D(d(x1:S)) -> B(a(c(x1:S)))
 D(d(x1:S)) -> C(x1:S)
-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))
->Strongly Connected Components:
->->Cycle:
->->-> Pairs:
 A(a(x1:S)) -> C(x1:S)
 A(a(x1:S)) -> D(c(x1:S))
 A(b(x1:S)) -> C(c(c(x1:S)))
 A(b(x1:S)) -> C(c(x1:S))
 A(b(x1:S)) -> C(x1:S)
 B(b(x1:S)) -> A(c(c(x1:S)))
 B(b(x1:S)) -> C(c(x1:S))
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
 C(d(x1:S)) -> A(a(x1:S))
 C(d(x1:S)) -> A(x1:S)
 D(d(x1:S)) -> A(c(x1:S))
 D(d(x1:S)) -> B(a(c(x1:S)))
 D(d(x1:S)) -> C(x1:S)
->->-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))

Problem 1: 

Reduction Pair Processor:
-> Pairs:
 A(a(x1:S)) -> C(x1:S)
 A(a(x1:S)) -> D(c(x1:S))
 A(b(x1:S)) -> C(c(c(x1:S)))
 A(b(x1:S)) -> C(c(x1:S))
 A(b(x1:S)) -> C(x1:S)
 B(b(x1:S)) -> A(c(c(x1:S)))
 B(b(x1:S)) -> C(c(x1:S))
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
 C(d(x1:S)) -> A(a(x1:S))
 C(d(x1:S)) -> A(x1:S)
 D(d(x1:S)) -> A(c(x1:S))
 D(d(x1:S)) -> B(a(c(x1:S)))
 D(d(x1:S)) -> C(x1:S)
-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))
-> Usable rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))
->Interpretation type:
 Linear
->Coefficients:
 All rationals
->Dimension:
 1
->Bound:
 4
->Interpretation:
 
[a](X) = X + 1
[b](X) = X + 1
[c](X) = X + 1/2
[d](X) = X + 3/2
[A](X) = 1/4.X + 3/4
[B](X) = 1/4.X + 3/4
[C](X) = 1/4.X + 3/4
[D](X) = 1/4.X + 3/4

Problem 1: 

SCC Processor:
-> Pairs:
 A(a(x1:S)) -> D(c(x1:S))
 A(b(x1:S)) -> C(c(c(x1:S)))
 A(b(x1:S)) -> C(c(x1:S))
 A(b(x1:S)) -> C(x1:S)
 B(b(x1:S)) -> A(c(c(x1:S)))
 B(b(x1:S)) -> C(c(x1:S))
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
 C(d(x1:S)) -> A(a(x1:S))
 C(d(x1:S)) -> A(x1:S)
 D(d(x1:S)) -> A(c(x1:S))
 D(d(x1:S)) -> B(a(c(x1:S)))
 D(d(x1:S)) -> C(x1:S)
-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))
->Strongly Connected Components:
->->Cycle:
->->-> Pairs:
 A(a(x1:S)) -> D(c(x1:S))
 A(b(x1:S)) -> C(c(c(x1:S)))
 A(b(x1:S)) -> C(c(x1:S))
 A(b(x1:S)) -> C(x1:S)
 B(b(x1:S)) -> A(c(c(x1:S)))
 B(b(x1:S)) -> C(c(x1:S))
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
 C(d(x1:S)) -> A(a(x1:S))
 C(d(x1:S)) -> A(x1:S)
 D(d(x1:S)) -> A(c(x1:S))
 D(d(x1:S)) -> B(a(c(x1:S)))
 D(d(x1:S)) -> C(x1:S)
->->-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))

Problem 1: 

Reduction Pair Processor:
-> Pairs:
 A(a(x1:S)) -> D(c(x1:S))
 A(b(x1:S)) -> C(c(c(x1:S)))
 A(b(x1:S)) -> C(c(x1:S))
 A(b(x1:S)) -> C(x1:S)
 B(b(x1:S)) -> A(c(c(x1:S)))
 B(b(x1:S)) -> C(c(x1:S))
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
 C(d(x1:S)) -> A(a(x1:S))
 C(d(x1:S)) -> A(x1:S)
 D(d(x1:S)) -> A(c(x1:S))
 D(d(x1:S)) -> B(a(c(x1:S)))
 D(d(x1:S)) -> C(x1:S)
-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))
-> Usable rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))
->Interpretation type:
 Linear
->Coefficients:
 All rationals
->Dimension:
 1
->Bound:
 4
->Interpretation:
 
[a](X) = X + 2/3
[b](X) = X + 2/3
[c](X) = X + 1/3
[d](X) = X + 1
[A](X) = 2.X + 4/3
[B](X) = 2.X + 4/3
[C](X) = 2.X + 2/3
[D](X) = 2.X + 4/3

Problem 1: 

SCC Processor:
-> Pairs:
 A(b(x1:S)) -> C(c(c(x1:S)))
 A(b(x1:S)) -> C(c(x1:S))
 A(b(x1:S)) -> C(x1:S)
 B(b(x1:S)) -> A(c(c(x1:S)))
 B(b(x1:S)) -> C(c(x1:S))
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
 C(d(x1:S)) -> A(a(x1:S))
 C(d(x1:S)) -> A(x1:S)
 D(d(x1:S)) -> A(c(x1:S))
 D(d(x1:S)) -> B(a(c(x1:S)))
 D(d(x1:S)) -> C(x1:S)
-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))
->Strongly Connected Components:
->->Cycle:
->->-> Pairs:
 A(b(x1:S)) -> C(c(c(x1:S)))
 A(b(x1:S)) -> C(c(x1:S))
 A(b(x1:S)) -> C(x1:S)
 B(b(x1:S)) -> A(c(c(x1:S)))
 B(b(x1:S)) -> C(c(x1:S))
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
 C(d(x1:S)) -> A(a(x1:S))
 C(d(x1:S)) -> A(x1:S)
->->-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))

Problem 1: 

Reduction Pair Processor:
-> Pairs:
 A(b(x1:S)) -> C(c(c(x1:S)))
 A(b(x1:S)) -> C(c(x1:S))
 A(b(x1:S)) -> C(x1:S)
 B(b(x1:S)) -> A(c(c(x1:S)))
 B(b(x1:S)) -> C(c(x1:S))
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
 C(d(x1:S)) -> A(a(x1:S))
 C(d(x1:S)) -> A(x1:S)
-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))
-> Usable rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))
->Interpretation type:
 Linear
->Coefficients:
 All rationals
->Dimension:
 1
->Bound:
 4
->Interpretation:
 
[a](X) = X + 4/3
[b](X) = X + 4/3
[c](X) = X + 2/3
[d](X) = X + 2
[A](X) = 2.X + 1/4
[B](X) = 2.X + 1/3
[C](X) = 2.X

Problem 1: 

SCC Processor:
-> Pairs:
 A(b(x1:S)) -> C(c(x1:S))
 A(b(x1:S)) -> C(x1:S)
 B(b(x1:S)) -> A(c(c(x1:S)))
 B(b(x1:S)) -> C(c(x1:S))
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
 C(d(x1:S)) -> A(a(x1:S))
 C(d(x1:S)) -> A(x1:S)
-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))
->Strongly Connected Components:
->->Cycle:
->->-> Pairs:
 A(b(x1:S)) -> C(c(x1:S))
 A(b(x1:S)) -> C(x1:S)
 B(b(x1:S)) -> A(c(c(x1:S)))
 B(b(x1:S)) -> C(c(x1:S))
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
 C(d(x1:S)) -> A(a(x1:S))
 C(d(x1:S)) -> A(x1:S)
->->-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))

Problem 1: 

Reduction Pair Processor:
-> Pairs:
 A(b(x1:S)) -> C(c(x1:S))
 A(b(x1:S)) -> C(x1:S)
 B(b(x1:S)) -> A(c(c(x1:S)))
 B(b(x1:S)) -> C(c(x1:S))
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
 C(d(x1:S)) -> A(a(x1:S))
 C(d(x1:S)) -> A(x1:S)
-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))
-> Usable rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))
->Interpretation type:
 Linear
->Coefficients:
 All rationals
->Dimension:
 1
->Bound:
 4
->Interpretation:
 
[a](X) = X + 2
[b](X) = X + 2
[c](X) = X + 1
[d](X) = X + 3
[A](X) = 2.X
[B](X) = 2.X + 1/2
[C](X) = 2.X + 2/3

Problem 1: 

SCC Processor:
-> Pairs:
 A(b(x1:S)) -> C(x1:S)
 B(b(x1:S)) -> A(c(c(x1:S)))
 B(b(x1:S)) -> C(c(x1:S))
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
 C(d(x1:S)) -> A(a(x1:S))
 C(d(x1:S)) -> A(x1:S)
-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))
->Strongly Connected Components:
->->Cycle:
->->-> Pairs:
 A(b(x1:S)) -> C(x1:S)
 B(b(x1:S)) -> A(c(c(x1:S)))
 B(b(x1:S)) -> C(c(x1:S))
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
 C(d(x1:S)) -> A(a(x1:S))
 C(d(x1:S)) -> A(x1:S)
->->-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))

Problem 1: 

Reduction Pair Processor:
-> Pairs:
 A(b(x1:S)) -> C(x1:S)
 B(b(x1:S)) -> A(c(c(x1:S)))
 B(b(x1:S)) -> C(c(x1:S))
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
 C(d(x1:S)) -> A(a(x1:S))
 C(d(x1:S)) -> A(x1:S)
-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))
-> Usable rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))
->Interpretation type:
 Linear
->Coefficients:
 All rationals
->Dimension:
 1
->Bound:
 4
->Interpretation:
 
[a](X) = X + 2
[b](X) = X + 2
[c](X) = X + 1
[d](X) = X + 3
[A](X) = 1/4.X + 2
[B](X) = 1/4.X + 2
[C](X) = 1/4.X + 2

Problem 1: 

SCC Processor:
-> Pairs:
 B(b(x1:S)) -> A(c(c(x1:S)))
 B(b(x1:S)) -> C(c(x1:S))
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
 C(d(x1:S)) -> A(a(x1:S))
 C(d(x1:S)) -> A(x1:S)
-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))
->Strongly Connected Components:
->->Cycle:
->->-> Pairs:
 B(b(x1:S)) -> C(c(x1:S))
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
->->-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))

Problem 1: 

Reduction Pair Processor:
-> Pairs:
 B(b(x1:S)) -> C(c(x1:S))
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))
-> Usable rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))
->Interpretation type:
 Linear
->Coefficients:
 All rationals
->Dimension:
 1
->Bound:
 4
->Interpretation:
 
[a](X) = X + 4/3
[b](X) = X + 4/3
[c](X) = X + 2/3
[d](X) = X + 2
[B](X) = 2.X + 1/4
[C](X) = 2.X + 2/3

Problem 1: 

SCC Processor:
-> Pairs:
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))
->Strongly Connected Components:
->->Cycle:
->->-> Pairs:
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
->->-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))

Problem 1: 

Subterm Processor:
-> Pairs:
 B(b(x1:S)) -> C(x1:S)
 C(c(x1:S)) -> B(x1:S)
-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))
->Projection:
 pi(B) = 1
 pi(C) = 1

Problem 1: 

SCC Processor:
-> Pairs:
 Empty
-> Rules:
 a(a(x1:S)) -> d(c(x1:S))
 a(b(x1:S)) -> c(c(c(x1:S)))
 b(b(x1:S)) -> a(c(c(x1:S)))
 c(c(x1:S)) -> b(x1:S)
 c(d(x1:S)) -> a(a(x1:S))
 d(d(x1:S)) -> b(a(c(x1:S)))
->Strongly Connected Components:
 There is no strongly connected component

The problem is finite.