13th International Conference on Membrane Computing - MTA Sztaki

H. ElGindy, R. Nicolescu, H. Wu
Pseudocode 5: Discard, adapted for G r−1 = (V, E r−1 )
1 Discard(σ i, G r−1)
2 Input : a cell to discard, σ i ∈ V , and the residual digraph, G r−1
3 i f σ i is permanently visited then return
4 set σ i as permanently visited
5 ioldreach = σ i.reach
6 σ i.reach = ∞
7 foreach arc (σ j, σ i) ∈ E r−1
8 i f (σ j, σ i) is temporarily visited then
9 fork Update(σ j, G r−1, ioldreach, σ i) // see Pseudocode 6
10 endif
11 set (σ j, σ i) as permanently visited
12 endfor
13 foreach temporarily visited arc (σ i, σ k )
14 fork Discard(σ k , G r−1)
15 endfor
Pseudocode 6: Update, adapted for G r−1 = (V, E r−1 )
1 Update(σ j, G r−1, ioldreach, σ i)
2 Input : a cell, σ j ∈ V , the residual digraph, G r−1, a reach-number, ioldreach,
3 and a cell, σ i ∈ V
4 i f σ j.reach = ioldreach then
5 newreach = σ j.depth
6 foreach temporarily visited arc (σ j, σ k ) ∈ E r−1
7 newreach = min(newreach, σ k .reach)
8 endfor
9 i f newreach > σ j.reach then
10 joldreach = σ j.reach
11 σ j.reach = newreach
12 foreach temporarily visited arc (σ k , σ j) ∈ E r−1
fork Update(σ k , G r−1, joldreach, σ j)
endfor
13 endif
14 if σ i.reach > σ j.depth then
fork Discard(σ i, G r−1)
endif
15 endif
Search round #r starts when cell σ s sends the forward token, together with
a depth indication of one (lines 3.8–11), to unvisited cell σ sr . When an unvisited
cell becomes visited, it becomes the new frontier cell, it marks itself as temporarily
visited (line 4.6), records its depth and reach-number as the received
depth (line 4.7), sends visited notification to all its neighbours (line 4.8–10). A
current frontier cell sends the forward token over an arbitrarily selected unvisited
arc, together with an incremented depth (lines 4.15–17). An unvisited cell
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