MAYBE

'Pop* (timeout of 60.0 seconds)'
--------------------------------
Answer:           MAYBE
Input Problem:    innermost runtime-complexity with respect to
  Rules:
    {  or(true(), y) -> true()
     , or(x, true()) -> true()
     , or(false(), false()) -> false()
     , mem(x, nil()) -> false()
     , mem(x, set(y)) -> =(x, y)
     , mem(x, union(y, z)) -> or(mem(x, y), mem(x, z))}

Proof Output:    
  The input cannot be shown compatible