MAYBE
* Step 1: Failure MAYBE
  + Considered Problem:
      - Strict TRS:
          double(0()) -> 0()
          double(s(x)) -> s(s(double(x)))
          exp(0()) -> s(0())
          exp(s(x)) -> double(exp(x))
          f(a(),0(),y) -> y
          f(a(),s(x),y) -> f(b(),y,s(x))
          f(b(),y,x) -> f(a(),half(x),exp(y))
          half(0()) -> double(0())
          half(s(0())) -> half(0())
          half(s(s(x))) -> s(half(x))
          tower(x) -> f(a(),x,s(0()))
      - Signature:
          {double/1,exp/1,f/3,half/1,tower/1} / {0/0,a/0,b/0,s/1}
      - Obligation:
          innermost runtime complexity wrt. defined symbols {double,exp,f,half,tower} and constructors {0,a,b,s}
  + Applied Processor:
      NaturalPI {shape = Mixed 3, restrict = NoRestrict, uargs = UArgs, urules = URules, selector = Nothing}
  + Details:
      Incompatible
MAYBE