YES
by ttt2 (version ttt2 1.15)
The rewrite relation of the following TRS is considered.
| a(b(x0)) | → | C(x0) | 
| b(c(x0)) | → | A(x0) | 
| c(a(x0)) | → | B(x0) | 
| A(C(x0)) | → | b(x0) | 
| C(B(x0)) | → | a(x0) | 
| B(A(x0)) | → | c(x0) | 
| a(a(a(a(x0)))) | → | A(A(A(x0))) | 
| A(A(A(A(x0)))) | → | a(a(a(x0))) | 
| b(b(b(b(x0)))) | → | B(B(B(x0))) | 
| B(B(B(B(x0)))) | → | b(b(b(x0))) | 
| c(c(c(c(x0)))) | → | C(C(C(x0))) | 
| C(C(C(C(x0)))) | → | c(c(c(x0))) | 
| B(a(a(a(x0)))) | → | c(A(A(A(x0)))) | 
| A(A(A(b(x0)))) | → | a(a(a(C(x0)))) | 
| C(b(b(b(x0)))) | → | a(B(B(B(x0)))) | 
| B(B(B(c(x0)))) | → | b(b(b(A(x0)))) | 
| A(c(c(c(x0)))) | → | b(C(C(C(x0)))) | 
| C(C(C(a(x0)))) | → | c(c(c(B(x0)))) | 
| a(A(x0)) | → | x0 | 
| A(a(x0)) | → | x0 | 
| b(B(x0)) | → | x0 | 
| B(b(x0)) | → | x0 | 
| c(C(x0)) | → | x0 | 
| C(c(x0)) | → | x0 | 
| prec(B) | = | 4 | weight(B) | = | 1 | ||||
| prec(A) | = | 1 | weight(A) | = | 1 | ||||
| prec(c) | = | 0 | weight(c) | = | 1 | ||||
| prec(C) | = | 7 | weight(C) | = | 1 | ||||
| prec(a) | = | 0 | weight(a) | = | 1 | ||||
| prec(b) | = | 0 | weight(b) | = | 1 | 
There are no rules in the TRS. Hence, it is terminating.