MAYBE

'Pop* (timeout of 60.0 seconds)'
--------------------------------
Answer:           MAYBE
Input Problem:    innermost runtime-complexity with respect to
  Rules:
    {  merge(nil(), y) -> y
     , merge(x, nil()) -> x
     , merge(.(x, y), .(u, v)) ->
       if(<(x, u), .(x, merge(y, .(u, v))), .(u, merge(.(x, y), v)))
     , ++(nil(), y) -> y
     , ++(.(x, y), z) -> .(x, ++(y, z))
     , if(true(), x, y) -> x
     , if(false(), x, y) -> x}

Proof Output:    
  The input cannot be shown compatible