That shares the impressive inefficiencies of the Quest for Tetris project, though. For something that's much more practical to run, and can be programmed to do things like print out the digits of pi in-universe, see
This is one of those tricky things, highly dependent on context.
If you're talking about Conway's Game of Life patterns, then "gliders" are the 5-cell spaceships that travel diagonally, and all other moving things are "spaceships" but not "gliders". If you call a Conway's Life non-glider spaceship a "glider" you'll mostly just confuse people.
But if you're talking about other CA rules -- especially rules where there isn't any 5-cell diagonal spaceship -- then "glider" is very commonly used to refer to other moving patterns.
For example, David Eppstein's "Gliders in Life-Like Cellular Automata" database was active for decades -- recording spaceships across a large rulespace, not just Conway's Life. It's an accepted generalization of the term, somewhat like saying "Xerox machine" for any old copying machine whether or not it was built by Xerox.
can be programmed to self-replicate in any number of ways, but it's so big that it's very hard to simulate it through a full cycle. By contrast, Pavel Grankovskiy's "DOGun SaGaQR"
OK, I didn't know if it was a "true" replicator (what even does "true" mean) so I excluded it. And, running a true replicator from other rule in 0E0P takes millenia, so that leaves DOGun SaGaQR (specifically the QR configuration). Sorry.
There are also patterns -- both stable patterns and oscillators -- that have an unbounded chain of predecessors, but still can't be glider constructed. That is, there are proven solutions to Conway's "Unique Father Problem" from over half a century ago:
https://conwaylife.com/wiki/Unique_father_problem
To put it another way, there are certain patterns that, if you see them in the Life grid, you know they've always been there from T=0 -- because they are provably their own only predecessor.
People have definitely tried this kind of thing, but so far -- from what I've seen -- Game of Life problems seem to be highly resistant to neural-net types of solutions.
Take spaceships, for example. You can train a neural net to recognize spaceships, but there aren't any reliably recognizable features that can distinguish a spaceship from a non-spaceship. To find out if a never-before-seen pattern is a spaceship with period N, you really have to run it for N ticks and see if you get the same pattern back again at an offset. Visual similarity with other spaceships just plain isn't relevant, unless the similarity is 100%; a pattern with a 99% match on a 100-cell spaceship will almost always be ... not a spaceship at all.
A good analogy for this might be training a neural net against images of prime numbers up to 997, printed in decimal in some standard font. Sure, you can train a neural net to recognize prime numbers less than 1000, with great accuracy ... but primality isn't a visual property of a printed number, it's something that you have to do some mathematical tests to find out about.
So if you try your trained neural net on prime numbers above 1000, you're going to be rather disappointed with its performance. CA spaceship recognition is the same kind of problem... possibly worse, since you could at least have some hope of a neural net correctly recognizing non-primes by their last digits.
Heh, I'm not actually sure whether Nathaniel meant to invoke Eric Raymond's hacker emblem on the book cover or not. The grid is there, and the glider orientation is right, but the cells are squares and not circles. That orientation of the glider is kinda canonical, independent of the hacker emblem -- e.g., it's the phase that shows up in the "glider" LifeWiki article.
I emailed back and forth a little bit with Eric Raymond when the hacker-emblem proposal first came out, but I don't remember that I had anything very interesting to say. Mostly I was hoping to get the Life Lexicon factoid about the unix oscillator into the "Anticipations" section on the official Hacker Emblem page --
Unix: ... The name derives from the fact that it was for some time the mascot of the Unix lab of the mathematics faculty at the University of Waterloo.
I'm thinking the most successful "automated exploration" so far has been Catagolue's method: simply generate a whole lot of random-soup initial configurations, run them until they settle, and then poke through the ashes looking for interesting stuff:
https://catagolue.hatsya.com/census
Seems like that gets the most emergent-behavior bang for your buck. All the other "automated search techniques" that I can think of are too specifically tailored to some particular problem.
There's definitely plenty of material for a Volume II book (and several volumes after that, for that matter). At the moment, though, Nathaniel and I think that it might be somebody else's turn to write those!
My sense is that people don't usually play the Immigration Game for very long -- it just doesn't seem all that interesting to most folks ... and so there hasn't been much interest in developing a computer opponent for the game.
It seems to be rather difficult to convert cellular automata into any kind of playable game. If it's an arcade game then it's usually too arbitrary, and if it's a puzzle game then it's usually way too easy or way too difficult. There have been some good efforts, but they're mostly only playable by dedicated Lifenthusiasts, and that's ... well... not a very large market!
Re: the LIFELINE public service announcement -- no need to do the scanning and online-ing. That's been done already, though there's still some review and typing-up work left for someone to do:
https://conwaylife.com/wiki/Pi_calculator