Rules for Siphon Extraction/Minimisation
20/3/2014
CE-653 - PTnet Theory and some
Algorithms
29
}Places in post-set of
transitions with empty pre-set cannot belong to a
siphon and can be eliminated
}If all transitions are in
post-set of some place, T = P• then P is a siphon (see Rule
3)
}Rule 4 [trap places elimination]
}Let G = (P, T, F) be a PTnet and let _T ≤ T be such
that
}•_T = Ø. Then, if _P = _T•, G has same siphons as
}~G = red(G, P - _P)
}Rule 5 [redundant places]
}Let G = (P, T, F) be a PTnet and S ≤ P a siphon of
G.
}If there exists _p in S:
for all t in _p• either
(t• ∩ S) > {_p} or
(•t ∩ S) = Ø, then S – {_p} is also a siphon of G
(t• ∩ S) > {_p} or
(•t ∩ S) = Ø, then S – {_p} is also a siphon of G
