def remove_initial_hidden_if_possible(net: PetriNet, im: Marking):
"""
Remove initial hidden transition if possible
Parameters
------------
net
Petri net
im
Initial marking
Returns
------------
net
Petri net
im
Possibly different initial marking
"""
source = list(im.keys())[0]
first_hidden = list(source.out_arcs)[0].target
target_places_first_hidden = [x.target for x in first_hidden.out_arcs]
if len(target_places_first_hidden) == 1:
target_place_first_hidden = target_places_first_hidden[0]
if len(target_place_first_hidden.in_arcs) == 1:
new_im = Marking()
new_im[target_place_first_hidden] = 1
remove_place(net, source)
remove_transition(net, first_hidden)
return net, new_im
return net, im
def remove_final_hidden_if_possible(net: PetriNet, fm: Marking):
"""
Remove final hidden transition if possible
Parameters
-------------
net
Petri net
fm
Final marking
Returns
-------------
net
Petri net
"""
sink = list(fm.keys())[0]
last_hidden = list(sink.in_arcs)[0].source
source_places_last_hidden = [x.source for x in last_hidden.in_arcs]
removal_possible = len(source_places_last_hidden) == 1
for place in source_places_last_hidden:
if len(place.out_arcs) > 1:
removal_possible = False
break
else:
source_trans = set([x.source for x in place.in_arcs])
for trans in source_trans:
if len(trans.out_arcs) > 1:
removal_possible = False
break
if removal_possible:
all_sources = set()
remove_transition(net, last_hidden)
i = 0
while i < len(source_places_last_hidden):
place = source_places_last_hidden[i]
source_trans = set([x.source for x in place.in_arcs])
for trans in source_trans:
if trans not in all_sources:
all_sources.add(trans)
add_arc_from_to(trans, sink, net)
remove_place(net, place)
i = i + 1
return net
