YES

Problem:
 a(x1) -> x1
 a(a(b(x1))) -> b(b(c(a(a(a(x1))))))
 c(a(x1)) -> x1

Proof:
 String Reversal Processor:
  a(x1) -> x1
  b(a(a(x1))) -> a(a(a(c(b(b(x1))))))
  a(c(x1)) -> x1
  DP Processor:
   DPs:
    b#(a(a(x1))) -> b#(x1)
    b#(a(a(x1))) -> b#(b(x1))
    b#(a(a(x1))) -> a#(c(b(b(x1))))
    b#(a(a(x1))) -> a#(a(c(b(b(x1)))))
    b#(a(a(x1))) -> a#(a(a(c(b(b(x1))))))
   TRS:
    a(x1) -> x1
    b(a(a(x1))) -> a(a(a(c(b(b(x1))))))
    a(c(x1)) -> x1
   TDG Processor:
    DPs:
     b#(a(a(x1))) -> b#(x1)
     b#(a(a(x1))) -> b#(b(x1))
     b#(a(a(x1))) -> a#(c(b(b(x1))))
     b#(a(a(x1))) -> a#(a(c(b(b(x1)))))
     b#(a(a(x1))) -> a#(a(a(c(b(b(x1))))))
    TRS:
     a(x1) -> x1
     b(a(a(x1))) -> a(a(a(c(b(b(x1))))))
     a(c(x1)) -> x1
    graph:
     b#(a(a(x1))) -> b#(b(x1)) -> b#(a(a(x1))) -> a#(a(a(c(b(b(x1))))))
     b#(a(a(x1))) -> b#(b(x1)) -> b#(a(a(x1))) -> a#(a(c(b(b(x1)))))
     b#(a(a(x1))) -> b#(b(x1)) -> b#(a(a(x1))) -> a#(c(b(b(x1))))
     b#(a(a(x1))) -> b#(b(x1)) -> b#(a(a(x1))) -> b#(b(x1))
     b#(a(a(x1))) -> b#(b(x1)) -> b#(a(a(x1))) -> b#(x1)
     b#(a(a(x1))) -> b#(x1) -> b#(a(a(x1))) -> a#(a(a(c(b(b(x1))))))
     b#(a(a(x1))) -> b#(x1) -> b#(a(a(x1))) -> a#(a(c(b(b(x1)))))
     b#(a(a(x1))) -> b#(x1) -> b#(a(a(x1))) -> a#(c(b(b(x1))))
     b#(a(a(x1))) -> b#(x1) -> b#(a(a(x1))) -> b#(b(x1))
     b#(a(a(x1))) -> b#(x1) -> b#(a(a(x1))) -> b#(x1)
    SCC Processor:
     #sccs: 1
     #rules: 2
     #arcs: 10/25
     DPs:
      b#(a(a(x1))) -> b#(b(x1))
      b#(a(a(x1))) -> b#(x1)
     TRS:
      a(x1) -> x1
      b(a(a(x1))) -> a(a(a(c(b(b(x1))))))
      a(c(x1)) -> x1
     Arctic Interpretation Processor:
      dimension: 2
      usable rules:
       a(x1) -> x1
       b(a(a(x1))) -> a(a(a(c(b(b(x1))))))
       a(c(x1)) -> x1
      interpretation:
       [b#](x0) = [0 0]x0,
       
                 [0  0 ]  
       [c](x0) = [-& -&]x0,
       
                 [0  -&]  
       [b](x0) = [0  -&]x0,
       
                 [0 2]  
       [a](x0) = [0 0]x0
      orientation:
       b#(a(a(x1))) = [2 2]x1 >= [0  -&]x1 = b#(b(x1))
       
       b#(a(a(x1))) = [2 2]x1 >= [0 0]x1 = b#(x1)
       
               [0 2]             
       a(x1) = [0 0]x1 >= x1 = x1
       
                     [2 2]      [2  -&]                         
       b(a(a(x1))) = [2 2]x1 >= [2  -&]x1 = a(a(a(c(b(b(x1))))))
       
                  [0 0]             
       a(c(x1)) = [0 0]x1 >= x1 = x1
      problem:
       DPs:
        
       TRS:
        a(x1) -> x1
        b(a(a(x1))) -> a(a(a(c(b(b(x1))))))
        a(c(x1)) -> x1
      Qed