Talk:Critters (cellular automaton)
Latest comment: 2 years ago by Cai in topic Are transition rules correct?
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Are transition rules correct? edit
These transition rules look wrong to me. They show an all-dead block transitioning to an all-live block, and vice versa. But this isn't shown in the animation where the whole infinite dead field doesn't flip from dead to alive and back each generation. I can't access the original book, but the Marotta ref shows a different set of transition rules (but also presents the rules in a different format). If the rules in the figure are wrong, the description in the text is also wrong. Cai (talk) 14:41, 2 April 2022 (UTC)
- "If the number of live cells is zero, one, or four, the transition function flips the state of every cell in the block. ... An alternative version of the transition function ..." The image shows the original rules, described in the first part of the quoted text. You are describing the alternative version. —David Eppstein (talk) 15:49, 2 April 2022 (UTC)
- OK, I see. It sounds like there are two CAs and they "look" very different though in some sense the dynamic behaviour is similar. The first has the feature that the whole field oscillates from fully alive to fully dead (flipping state of all cells in all blocks with 0 or 4 live cells), the second has the feature that the dead field stays dead until reached by some alive cell. Is that right? From reading the text I had thought both versions of the rules gave rise to the "same" CA in a more directly literal sense. Cai (talk) 04:33, 3 April 2022 (UTC)
- The detailed behavior is the same. The original version is exactly the same as the second version in even generations. In odd generations it is exactly complementary to the second version. —David Eppstein (talk) 04:58, 3 April 2022 (UTC)
- Ah, I get it now. It's the same if you complement the "image" (but not the cell states) on every other step. So in the first rules, you do get a "flicker" of the whole field, which you can "ignore" by using active-shutter glasses ;) I'll expand the text slightly to make this more clear, for myself in future if nothing else. Thank you for explaining. Cai (talk) 06:04, 3 April 2022 (UTC)
- The detailed behavior is the same. The original version is exactly the same as the second version in even generations. In odd generations it is exactly complementary to the second version. —David Eppstein (talk) 04:58, 3 April 2022 (UTC)
- OK, I see. It sounds like there are two CAs and they "look" very different though in some sense the dynamic behaviour is similar. The first has the feature that the whole field oscillates from fully alive to fully dead (flipping state of all cells in all blocks with 0 or 4 live cells), the second has the feature that the dead field stays dead until reached by some alive cell. Is that right? From reading the text I had thought both versions of the rules gave rise to the "same" CA in a more directly literal sense. Cai (talk) 04:33, 3 April 2022 (UTC)