Random Explorations in Automata Theory Gary J. Shannon Created: Mar. 25, 2003 Last updated: Mar. 25, 2003

BugWars: A Battle between Acid Bugs

Using the PPR rule method I created a second species of bug identical to the reb/blue bug that squirms around in the "acid bath" rule. The other species is yellow/black. Each species of bug lives in a different kind of acid and they share nothing in common except their hunger for empty (state 1, white) cells to gobble up. Starting with two isolated colonies each began digging its way through the solid material around their colony (state 0, grey).

[This is the first of a series of bug war CAs. The second bug war uses two species of acid bugs that live in the same color acid, and try to build barriers between their colonies.]

Fig. 1. An intrepid digger from the red acid colony reaches out to the
yellow acid colony.

It's interesting to note that acid bugs need about 75x75 cells worth of space for the colony to have a good chance to survive. In a space of 50x50 the colony only lasts about 1000 generations on average before dying out completely. Above 100x100 it seems to last forever. So what's going to happen when one kind of acid starts leaking into the territory of the other kind of bug?

Fig. 2. 1000 generations after first contact.

In figure 2 notice that the red acid is starting to spread into the yellow acid. The black acid bugs are powerless to stop it. But it doesn't spread very fast because in the rules yellow acid takes precedence over red acid when both are trying to grab an empty (white) cell. So yellow is able to hold red at bay for quite a while.

Fig. 3. Another 1000 generations later.

In figure 3 the large mass of the colonies is about to touch.

Fig. 4. First contact of the main masses.

Fig. 5. Only 100 generations after figure 4, the yellow acid is spreading fast and contaminating
environment of the blue acid bugs.

Fig. 6. 400 generations later and the yellow is spreading fast.

Fig. 7. 1000 generations after figure 6 and the yellow acid has killed all
of the blue acid bugs and destroyed the colony. But wait...

Fig. 8. The red acid is still seeping into the yellow acid, cramping the
black acid bugs for space. 1200 generations since figure 7.

Fig. 9. Finally, 8,000 generations after figure 8, enough red
acid seeps into the yellow/black colony  to destroy all of
the black acid bugs.

For anyone who wants to play with this rule here is the MCell ppr file for the rule. It requires the MCell DLL that supports the ppr rules that can be downloaded here. The MCell Program itself can be found here.

You can cut and paste these lines into a text editor and save it as "dual acid.ppr" in the ppr directory under UserDLLs in MCell.

M,8
1(2)2
2(3)3
3(*)1
2(4)3
0(2,3)1
2(3,1)0
3(2,1)0
3(-2)3
1(5)5
5(6)6
6(*)1
5(7)6
0(5,6)1
5(6,1)0
6(5,1)0
6(-5)6