fluents: clogged(T) requires toilet(T). armed(P) requires package(P). unsafe. actions: dunk(P,T) requires package(P), toilet(T). flush(T) requires toilet(T). always: inertial armed(P). inertial clogged(T). caused -clogged(T) after flush(T). caused -armed(P) after dunk(P,T). total clogged(T) after dunk(P,T). caused unsafe if armed(P). executable flush(T). executable dunk(P,T) if not clogged(T). initially: total armed(P). caused false if armed(P), armed(P1), P <> P1. caused false if not unsafe. securePlan. goal: not unsafe?