}Places with empty subset and places with all net transitions as post-set are special
cases!
}
}Rule 2 [empty subset places]
}Let G = (P, T, F) be
PTnet and _P ≤ P such that •_P = Ø
}Then, minimal siphons of
G are minimal siphons of
~G = red(G, P - _P), plus the individual places in _P
}
}Rule 3 [all net transitions in
post-set places]
}Let G = (P, T, F) be a
PTnet such that P• = T
}Then P is a siphon
}