MAYBE

'Pop* with parameter subtitution (timeout of 60.0 seconds)'
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Answer:           MAYBE
Input Problem:    innermost runtime-complexity with respect to
  Rules:
    {  f(x, a(b(c(y)))) -> f(b(c(a(b(x)))), y)
     , f(a(x), y) -> f(x, a(y))
     , f(b(x), y) -> f(x, b(y))
     , f(c(x), y) -> f(x, c(y))}

Proof Output:    
  The input cannot be shown compatible