Graphics Programs Reference
In-Depth Information
t
l
p
k
t
m
Figure 2.15: An example of HME relation: t
l
HME t
m
t
l
t
m
Figure 2.16: An example of MME relation: t
l
MME t
m
Definition 2.5.6 Transition t
l
is mutually exclusive with t
m
due to in-
hibitor arcs ( t
l
HME t
m
) if and only if
∃
p
k
∈
P :
•
0 < H(t
l
,p
k
)
≤
I(t
m
,p
k
) or
•
0 < H(t
m
,p
k
)
≤
I(t
l
,p
k
)
Mutual exclusion due to invariants is called MME and it is based on the
observation that the token count of a P-invariant may prevent t
l
and t
m
from having simultaneously concession in any reachable marking due to a
lack of tokens in their input places; an example is shown in Fig.
2.16.
Definition 2.5.7 Transition t
l
is mutually exclusive with transition t
m
due
to P-invariants, t
l
MME t
m
iff
∃
Y
∈
PS (the set of minimal P-
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