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All 23-Bit Still Lifes Are Glider Constructible

mvr.github.io

11–17 of 17 posts

Re: All 23-Bit Still Lifes Are Glider Constructible

#11

This is a cool subcommunity! Had no idea there were still open problems that people were working on. Surprised to see human intuition is still around – would have expected a solution through pure brute force.

The state space is much too large for generic brute-forcing. The number of possible patterns in a 16 x 16 grid is already roughly the number of atoms in the universe, or 10^31 years in Planck time units.

Re: All 23-Bit Still Lifes Are Glider Constructible

#12
I just found out that there's a 1D cellular automaton called Rule 54 that is conjectured to be Turing complete, but for which there isn't yet a proof.

I think Gemini (an LLM) and me are in agreement that the proof will likely be found by a neuro-symbolic AI. As evidence for this, see AlphaEvolve and the agents which received IMO Gold.

Re: All 23-Bit Still Lifes Are Glider Constructible

#14
post #3

Earlier quoted context omitted.

In that respect, it reminds me a bit of the busy beaver problem. I wonder: consider the decision problem of determining whether or not a given still life is glider-constructible. Is this problem known to be undecidable? It's straightforward to show that an "inverse" of this problem -- given an arbitrary glider construction sequence, does it result in a still life? -- is undecidable, because gliders can construct patt…

Is it that easy though? Because the Turing machine constructions we have in the game of life are clearly not still lifes, and I don't know if you can construct a Turing machine which freezes into a still life upon halting.

You can make a Turing machine that contains self-destruct circuitry which destroys all moving parts upon halting. The resulting pattern will be a (pseudo) still life.

Re: All 23-Bit Still Lifes Are Glider Constructible

#15
post #9

It's annoying here that you can't run CGoL in reverse, like you can with the laws of physics. Someone should invent a GoL (that is still interesting) with that property.

You'll be pleased to find out about Critters:

https://en.wikipedia.org/wiki/Critters_(cellular_automaton)

Re: All 23-Bit Still Lifes Are Glider Constructible

#17
post #9

It's annoying here that you can't run CGoL in reverse, like you can with the laws of physics. Someone should invent a GoL (that is still interesting) with that property.

You'll be pleased to find out about Critters: https://en.wikipedia.org/wiki/Critters_(cellular_automaton)

Thanks, very interesting!
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