MAYBE

We are left with following problem, upon which TcT provides the
certificate MAYBE.

Strict Trs:
  { del(.(x, .(y, z))) -> f(=(x, y), x, y, z)
  , f(true(), x, y, z) -> del(.(y, z))
  , f(false(), x, y, z) -> .(x, del(.(y, z)))
  , =(.(x, y), .(u(), v())) -> and(=(x, u()), =(y, v()))
  , =(.(x, y), nil()) -> false()
  , =(nil(), .(y, z)) -> false()
  , =(nil(), nil()) -> true() }
Obligation:
  innermost runtime complexity
Answer:
  MAYBE

The input cannot be shown compatible

Arrrr..