That's a beautifully concise numbering system for sharing being used there.
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.)
InChI is not designed as, nor can used for, what you propose. Last I checked, conversion from an InChI to a structure format was not a supported option, and only exists for testing purposes. Which is not to say that people don't use for that. (Also, last I checked, there are inputs which cause InChI to segfault. And there's no spec for how to interpret InChIs other than to run the reference code.)
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.
It does help that Game of Life physics is somewhat simpler than Real Life physics. Of course, 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.
This is the slowest spaceship known, right? (Which isn't a machine made out of other parts?)
Topologically, encoding a 2D structure into a 1D line of text is dramatically simpler than encoding a 3D structure into a 1D line of text. To motivate this simply, recall that no graph whose minors include K5 or K3,3 can be drawn in the plane, whereas any graph can be drawn in 3D. It gets even simpler because all GoL graphs are confined to a grid.
> Now if only we had descriptions of chemistry that were this terse.
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.)
if InChI doesn't do it for you, i suppose SMILES[1] isn't sufficient either? By-the-bye, you're not ever going to be able to "concisely" encode 3d (or even 2d coordinate) structures, because there isn't just one such. They're a thermally sampled average of structures.
Chemistry isn't even fully expressible using naive graph structures (atoms = vertices, bonds = edges), for example, eta-2 metal-pi bonds where the chemical bond is between an atom and another bond.
The terseness vanishes when considering the complexities of interactions and possible classifications. In fact, I'd say that the above terseness is only possible because it's about half of ALL the interesting effects possible in the game of life.
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
"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.
I'm no life expert, but this proof doesn't work for me. Just because there exists some configuration that doesn't generate lifelines in your chosen directions, doesn't mean that any particular configuration doesn't generate lifelines in those directions.
I'm thinking about writing a Conway's Life MMO, where you can activate "lanterns" that illuminate rectangles in the grid with Conway Life squares. These lanterns are fueled with "living" Conway Life cells, which are harvested by the player. Sound interesting?
Honestly no. Building an MMO that ran entirely on life would be amazing but probably impossible. Building something that used the trappings of life without having it mean much would just be infuriating. Unless I'm misunderstanding the proposal?
Maybe a turn-based roguelike where the monsters are lifeforms that follow the rules of GoL. Could either be very interesting or exceedingly boring once it settled into a self-sustaining pattern.
It is. Someone discovered that if you start with that initial pattern you get a "spaceship" that moves. I gather that it is an impressive find both because of how small it is (you'd expect someone or a computer to have already discovered it) and how slow it moves.
[+] [-] pervycreeper|10 years ago|reply
[+] [-] vehementi|10 years ago|reply
[+] [-] jessriedel|10 years ago|reply
[+] [-] heavenlyhash|10 years ago|reply
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.)
[+] [-] dalke|10 years ago|reply
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.
[+] [-] david-given|10 years ago|reply
This is the slowest spaceship known, right? (Which isn't a machine made out of other parts?)
[+] [-] scythe|10 years ago|reply
tl;dr: easier problem is easier!
[+] [-] creshal|10 years ago|reply
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.)
[+] [-] theophrastus|10 years ago|reply
[1] https://en.wikipedia.org/wiki/Simplified_molecular-input_lin...
[+] [-] dnautics|10 years ago|reply
[+] [-] duaneb|10 years ago|reply
[+] [-] theoh|10 years ago|reply
[+] [-] ticklemyelmo|10 years ago|reply
[+] [-] shmerl|10 years ago|reply
[+] [-] aab0|10 years ago|reply
[+] [-] jarin|10 years ago|reply
[+] [-] nkrisc|10 years ago|reply
[+] [-] cakeface|10 years ago|reply
[+] [-] tod222|10 years ago|reply
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
[+] [-] jonah|10 years ago|reply
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.
[+] [-] sklogic|10 years ago|reply
[+] [-] xamuel|10 years ago|reply
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.
[+] [-] jessaustin|10 years ago|reply
[+] [-] DerekL|10 years ago|reply
This statement seems incorrect. It's true that every living cell has a living mother, but there's no requirement of a living father.
[+] [-] invisibowl|10 years ago|reply
[+] [-] stcredzero|10 years ago|reply
[+] [-] lmm|10 years ago|reply
[+] [-] nkrisc|10 years ago|reply
[+] [-] iamwil|10 years ago|reply
This link has an animation of the c/10 spaceship.
[+] [-] stephenitis|10 years ago|reply
[+] [-] baddox|10 years ago|reply
[+] [-] stefs|10 years ago|reply
[+] [-] unknown|10 years ago|reply
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[+] [-] tommoose|10 years ago|reply
[+] [-] Mauricio_|10 years ago|reply