13th International Conference on Membrane Computing - MTA Sztaki

Mobile membranes with objects on surface as colored Petri nets
• the substitution transition exo2-step4 simulates the mobile membrane rule 8
from the description of the LDL degradation pathway;
• the substitution transition exo3-step4 simulates the mobile membrane rule 9
from the description of the LDL degradation pathway.
We may observe that the marking of places appearing in Figure 4 are similar
with the one of the corresponding places of Figure 3. The substitution transition
exo1-step4 is replaced by the Petri net presented in Figure 5.
Fig. 5. Exo1 Step 4 Transition
In Figure 6, the enabled transition is phagostep2 which is surrounded by a
green shadow. It removes a token apoB from place apoB protein(2), a token
recep from place cell(5), and two tokens (0, 2) and (0, 5) from place structure.
The arc expression of the input arc from the place structure are (x, 2) and (y, 5),
and so they are tested using the test expression [x=0, y=0]. The test is performed
in order to see that the simulated membranes 2 and 5 have the same parent 0.
Fig. 6. Phago Step 2 Transition
After firing the transition, a token recep is added to the place aux1(6), a token
apoB is added to the place apoB protein(2), and three tokens (0, 5), (6, 2) and
(5, 6) are added to the place structure1.
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