YES

Problem 1: 

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

Problem 1: 

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

Problem 1: 

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

Problem 1: 

Reduction Pair Processor:
-> Pairs:
 A(a(x1:S)) -> B(x1:S)
 A(b(x1:S)) -> A(a(a(x1:S)))
 A(b(x1:S)) -> A(a(x1:S))
 A(b(x1:S)) -> A(x1:S)
 A(b(x1:S)) -> B(a(a(a(x1:S))))
 B(a(x1:S)) -> A(a(x1:S))
-> Rules:
 a(a(x1:S)) -> a(c(b(x1:S)))
 a(b(x1:S)) -> b(a(a(a(x1:S))))
 b(a(x1:S)) -> a(a(x1:S))
-> Usable rules:
 a(a(x1:S)) -> a(c(b(x1:S)))
 a(b(x1:S)) -> b(a(a(a(x1:S))))
 b(a(x1:S)) -> a(a(x1:S))
->Interpretation type:
 Linear
->Coefficients:
 Natural Numbers
->Dimension:
 1
->Bound:
 2
->Interpretation:
 
[a](X) = X
[b](X) = 2.X + 1
[c](X) = 0
[A](X) = 2.X
[B](X) = 2.X

Problem 1: 

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

Problem 1: 

Reduction Pair Processor:
-> Pairs:
 A(a(x1:S)) -> B(x1:S)
 A(b(x1:S)) -> A(a(x1:S))
 A(b(x1:S)) -> A(x1:S)
 A(b(x1:S)) -> B(a(a(a(x1:S))))
 B(a(x1:S)) -> A(a(x1:S))
-> Rules:
 a(a(x1:S)) -> a(c(b(x1:S)))
 a(b(x1:S)) -> b(a(a(a(x1:S))))
 b(a(x1:S)) -> a(a(x1:S))
-> Usable rules:
 a(a(x1:S)) -> a(c(b(x1:S)))
 a(b(x1:S)) -> b(a(a(a(x1:S))))
 b(a(x1:S)) -> a(a(x1:S))
->Interpretation type:
 Linear
->Coefficients:
 Natural Numbers
->Dimension:
 1
->Bound:
 2
->Interpretation:
 
[a](X) = X
[b](X) = X + 2
[c](X) = 0
[A](X) = X
[B](X) = X

Problem 1: 

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

Problem 1: 

Reduction Pair Processor:
-> Pairs:
 A(a(x1:S)) -> B(x1:S)
 A(b(x1:S)) -> A(x1:S)
 A(b(x1:S)) -> B(a(a(a(x1:S))))
 B(a(x1:S)) -> A(a(x1:S))
-> Rules:
 a(a(x1:S)) -> a(c(b(x1:S)))
 a(b(x1:S)) -> b(a(a(a(x1:S))))
 b(a(x1:S)) -> a(a(x1:S))
-> Usable rules:
 a(a(x1:S)) -> a(c(b(x1:S)))
 a(b(x1:S)) -> b(a(a(a(x1:S))))
 b(a(x1:S)) -> a(a(x1:S))
->Interpretation type:
 Linear
->Coefficients:
 Natural Numbers
->Dimension:
 1
->Bound:
 2
->Interpretation:
 
[a](X) = X
[b](X) = 2.X + 2
[c](X) = 0
[A](X) = 2.X
[B](X) = 2.X

Problem 1: 

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

Problem 1: 

Reduction Pair Processor:
-> Pairs:
 A(a(x1:S)) -> B(x1:S)
 A(b(x1:S)) -> B(a(a(a(x1:S))))
 B(a(x1:S)) -> A(a(x1:S))
-> Rules:
 a(a(x1:S)) -> a(c(b(x1:S)))
 a(b(x1:S)) -> b(a(a(a(x1:S))))
 b(a(x1:S)) -> a(a(x1:S))
-> Usable rules:
 a(a(x1:S)) -> a(c(b(x1:S)))
 a(b(x1:S)) -> b(a(a(a(x1:S))))
 b(a(x1:S)) -> a(a(x1:S))
->Interpretation type:
 Linear
->Coefficients:
 Natural Numbers
->Dimension:
 1
->Bound:
 2
->Interpretation:
 
[a](X) = X
[b](X) = X + 2
[c](X) = 0
[A](X) = 2.X
[B](X) = 2.X

Problem 1: 

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

Problem 1: 

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

Problem 1: 

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

The problem is finite.