Is this c/10 spaceship known?
conwaylife.com
conwaylife.com
Now if only we had descriptions of chemistry that were this terse. Imagine if this kind of problem solving, collaboration, simulation, and instant verification were the norm for synthetic chem. One of the comments -- "[Let's] use gencols to rub the ship against gliders and *WSSs to see whether there is a useful collision to maybe build a puffer" -- just blew me away. If this were chemistry, that commentator would have been suggesting automatic nanomachine factory discovery.
(InChI appears to be close. But vast amounts of data are locked up in obtuse formats are either Assigned-Names-And-Numbers style formats which are useless to indexing and similarity searches, or formats that embed non-relative coordinates in 3d space, etc, in such a way that computing a deterministic ID for sharing is practically a nonstarter.)
The InChI normalization step may also change the chemistry. For example, it may put things into a preferred tautomer form or charge state. This is essential for its goal of linking disparate records, but it is not chemistry preserving, and can be worse than passing an SD file to your nanomachine factory.
It was designed as "deterministic ID for sharing", yes, but not for sharing structure information but rather information related to the structure.
The most "concise" solution is to record the positions of the nuclei and the total charge. Then any quantum mechanics program will be able to reconstruct (to the desired level of approximation) the electron density of the molecule. This is the one you reject.
For good reasons. As you say, you want a nomenclature that can help with identity and similarity, and electron density is a very slow way to do that.
But such nomenclature is driven by human concepts. Fundamentally, there are different reaction rates depending on the relative orientation of two molecules. We see this in molecular beam experiments. For example, from 1979, http://www.sciencedirect.com/science/article/pii/00092614798... "Molecular beam reaction of K atoms with sideways oriented CF3I".
InChI doesn't have a special name for "sideways oriented CF3I", even though a complete, concise system would have to be able to provide a name for it.
Instead, we've come up with concise approximations - a SMILES string, a bitstring fingerprint, etc. - which are tractable for the purposes you want, so long as we stay within relatively normal chemistry. But it's still humans who categorize things into, say, "aromatic" or "chiral", so our approximate nomenclature has to partially encode how humans think of chemistry.
The Game of Life is much simpler than the Reality of Life.
Though the Game of Life is surely simpler than the Reality of Life... if one were to flat out name the core concept as "godel numbers for chemical formations", it's certainly possible, don't you think? InChI isn't it, I agree; just wanted to toss the seed of the idea out there, with an example that's a lot "closer" to the target semiotics than a bunch of unnormalized floating point coordinates drifting around in xml.
"good enough is the enemy of good" can apply in spades here, so I appreciate your thorough analysis of specific weak points in InChI.
InChI is only closer for the classical purpose of chemical documentation - record association and text-based search. That is not a bad thing, but given the entirety of your goals, it is equally correct to use "close" for SMILES, SLN, SD, Mol2, etc.
This is the slowest spaceship known, right? (Which isn't a machine made out of other parts?)
It also helps that Games of Life can be saved and reloaded. If your lab bench explodes, too bad, start over from scratch (assuming you're uninjured).
(cough)
Are we sure of that yet?
> Real Life physics is a little less apt to collapse into a seething mass of undifferentiated matter of you poke it in the wrong place.
Are we sure of that yet?
RL follows quantum mechanics. As far as we know, its state cannot be recorded perfectly.
GoL is a Turing Machine. Its state can be recorded perfectly.
RL follows relativity. There is no equivalent in GoL.
Hashlife gives a method to compute GoL boards faster than processing each cell, and gives an exact answer. There is no equivalent for RL. At best there are probabilistic predictions. (There might be a 1E-50000 chance that the Sun won't rise tomorrow because all of the atoms in the Sun fuse at the same time and it blows up.)
Of course there is an equivalent of relativity! There's a fixed, ultimate speed-limit (i.e. c) of once-cell/time-step. It is not possible to transmit information faster than this in GoL.
https://en.wikipedia.org/wiki/Superfluid_vacuum_theory#Relat...
"Relativistic quantum field theory"
This is already experimentally observed in our own universe. Quantum noise exists in vacuums.
If you look at C in GoL as the fastest an actual black square can propagate, then of course you'll validate your naive assumptions that our universe could never be digitally replicated by GoL. But if you take the idea of implementing a primordial sea of quantum noise, and looking at the GoL board not as physical particles directly, but as a deeper construct. Then you can actually replicate relativity.
To estimate probability of an event you must have a sample were both have occurred, to provide a probability for something like the Sun not rising tomorrow is pure non-sense.
The same can't be said for the atoms in the sun.
You also have to make an arbitrary decision about when the cannonball touches the ground. How much interaction is needed between the atoms of the cannonball and ground before you say there's contact?
These issues don't exist in the GoL universe.
Outside the universe ain't. But even though, I can confidently say that we are definitely inside.
Not a very tangible idea, but not useless of purpose of reasoning about the affairs of things.
tl;dr: easier problem is easier!
Chemistry is dealing with a lot, lot more of concepts than the study of the Game of Life. Brevity only works when you have few enough information that you can map it to only concise words.
(Entropy strikes again, even if it's information entropy for a change.)
Information entropy and physics entropy are actually the same thing. You can measure heat capacity in bits.
[1] https://en.wikipedia.org/wiki/Simplified_molecular-input_lin...
SMILES is better at #1 than InChI, but not as good as a 3D structure representation. But the 3D structure isn't as compact, and offers few advantages for structure identity for small molecules where the 3D configuration is more easily predicted from geometry.
InChI is better for #2 than SMILES because different tools generate a different canonical structure, and because general purpose text search engines like Google don't do so well with SMILES as InChI keys.
Fingerprints, either binary or count, are more often used for the similarity aspect of #3, than n-gram solutions using the SMILES directly (like LINGO), or any method based on InChI. Also common are 3D shape and electrostatics comparison methods, with attempts to sample configuration space.
And for certain chemical structures other approximations are even more important. DNA similarity is based on very different principles than used for small molecules.
Very close, yes. But if we compare to, say, reproducible builds (because it's also dear to my heart), the consequences of that difference are legion. For example: the `tar` command can definitely extract you a filesystem, yes, absolutely. However: whether or not two `tar` implementations (or even the same implementation, run twice in a row) produce the same byte stream is make-or-break for whether someone else can follow your procedure and get the same result.
If the process is deterministic, the identity check is cheap: hash it. If the process requires unpacking again to do semantic checks on the contents, the amount of time is... well, if we're hand-waving on the format, essentially unbounded.
So... yeah, "canonical SMILES" is a valid answer; that "canonical" part is just really important.
For a variation on the theme, if we all agreed on a canonical SMILES method, then the SHA256 of that could be used as a key to connect records, without revealing what the underlying structure is.
This is done now, with InChI Key, when two companies want to compare overlap without sharing information about internal compounds. (There was a paper about this last year or so, but I can't find it.)
I also pointed out that InChI Keys are better for text-based search engines. As an extreme example, I could produce a line notation which uses only the characters "(", ")", ".", and "-". It would be fine for #1, but poor for #2 for any database search engine which expects some concept of "words" made of letters.
This is why I distinguish #1 from #2, even though they are indeed close.
Some members recently have put together a distributed soup search project to catalog objects that appear naturally. While the c/10 spaceship wasn't found in the search, a number of interesting things have been discovered. For more information about the catalog effort (named "catagolue" for Game of Life), the object database, and the distributed client, see http://catagolue.appspot.com/home
orthogonal spaceship, glider, puffer, rake, loafer.
"Trying to perfect a rake so it does not create Methuselah which eventually evolves into loaves, beehives and traffic lights isn't normal. But on Conway's Life, it is. Life. Not even once." - 'muzik
"- Use gencols to rub the ship against gliders and *WSSs to see whether there is a useful collision to maybe build a puffer." - 'HartmutHolzwart
And the excitement exhibited over this discovery. Very cool.
You might be interested in a simple proof I found of why c/2 and c/3 are speed limits for orthogonal and diagonal spaceships respectively.
Definition: In a gameplay of life, an "infinite lifeline" is a sequence of pairs (c_i,n_i) such that each c_i is alive in generation n_i and either c_(i+1)=c_i or c_(i+1) is adjacent to c_i.
Lemma ("Two Forbidden Directions"): Let x,y be any two 'forbidden' directions from among N,S,E,W,NE,NW,SE,SW. In any gameplay of life that starts finite and doesn't die out, there is an infinite lifeline that never goes in either direction x or y.
The lemma's proof uses biology. Say that (c,n) is a "father" of (c',n+1) if c' is the cell adjacent to c in direction x or y. Otherwise, (c,d) is a "mother" of (c',n+1). By the rules of the game of life it's easy to show every living (c,n+1) has at least one living father and at least one living mother. It follows (modulo some more details) that since the gameplay doesn't die out, there must be an infinite lifeline where each cell is a mother of the next, i.e., an infinite lifeline that never goes direction x or y.
Proof of c/2 orthogonal speed limit: If a spaceship went faster than c/2, say, northward, by the lemma, it would have an infinite lifeline that never goes N or NE. The only way it could ever go northward would be to go NW. Every NW step would have to be balanced out by an eastward step (of which NE is forbidden) or the spaceship would drift west. So every northward step requires a non-northward step, QED.
Proof of c/3 speed limit for diagonal: A diagonal spaceship faster than c/3, say, northeastward, would have an infinite lifeline that never goes N or NE. The only way for it to go northward would be to go NW. Each NW step would need at least two eastward steps in order for the ship to go eastward, QED.
The lemma says that in any configuration which starts finite and never dies out, there DOES exist at least one lifeline which DOESN'T go in a forbidden direction. (There are almost certainly lots of other lifelines which do go in forbidden directions, that's fine.)
An example of a lifeline in a southeastward spaceship that never goes S or SE: http://www.xamuel.com/images/lifeline.gif
The proof I outlined above was published in the Elect. J. of Combinatorics (last section): http://www.combinatorics.org/ojs/index.php/eljc/article/view...
This statement seems incorrect. It's true that every living cell has a living mother, but there's no requirement of a living father.
Your father might have died before you were born but he didn't die before he himself was born.
I handwaved that bit anyway for expediency, if you're interested in the full details see: http://www.combinatorics.org/ojs/index.php/eljc/article/view...
The life structures you need to start would just be glider guns. The glider guns would fire into walls of "collector cells" which are not Conway Life entities, but are implemented by the game directly.
Likewise, the character is not a Conway Life entity, but implemented directly by the game.
I think that's going to be unplayably difficult for anyone except serious programmers
What I've envisioned might well be appreciated by Life enthusiasts.
To the extent that resource collection involves stuff happening in Life you will struggle to balance it, and to the extent that it doesn't it's not really life-based at all.
Obviously, because no MMOs have contrived mechanics, ever!
Seems to me Life has a lot of potential as abstract art, though. I'm almost curious enough about what they're doing in Second Life these days, to sign up and go have a look:
http://www.conwaylife.com/forums/viewtopic.php?f=7&t=2068#p2...
This link has an animation of the c/10 spaceship.
What's new here, apparently, is that this is the first glider discovered with that speed. It also is surprisingly small.