
Is this c/10 spaceship known? - morninj
http://www.conwaylife.com/forums/viewtopic.php?f=2&t=2057
======
pervycreeper
This writeup (found a few pages into the thread) explains things in a little
bit more detail for a newcomer.
[https://niginsblog.wordpress.com/2016/03/07/new-spaceship-
sp...](https://niginsblog.wordpress.com/2016/03/07/new-spaceship-speed-in-
conways-game-of-life/)

~~~
vehementi
That is an awesome post and gives hints into the depth the community has gone
into the conway game

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heavenlyhash
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.)

~~~
dalke
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...](http://www.sciencedirect.com/science/article/pii/0009261479803851)
"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.

~~~
heavenlyhash
All of this is true. The word "close" was chosen very, very deliberately.

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.

~~~
dalke
InChI is not closer but actually further than SMILES or SD files for many of
the use cases you wanted. It is not a supported capability to turn an InChI
into a structure, which makes it hard to generate, say, a fingerprint for a
Tanimoto search system. (Yes, the command-line tools and its wrappers support
that, but the InChI developers do not condone its use. Even if you do so, the
output may differ from your input structure in ways you disagree with.)

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.

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ticklemyelmo
Hint: Click "Show in viewer" in the first message. Zoom out a bit. Press play.

~~~
shmerl
Thanks for the hint, I was just trying to dig up Golly to test it :)

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nkrisc
Skimming through the thread, I realized I had no idea of the type of community
that exists surrounding Conway's game. I think it's awesome.

~~~
cakeface
I know! There is probably some corollary to Rule 34 that states that for every
obscure topic there is an internet forum of people dedicated to it.

~~~
chc4
There is, naturally, a relevant XKCD about this:

[https://xkcd.com/1095/](https://xkcd.com/1095/)

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jonah
I just love all the lingo in little specialized communities.

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
Most of the language was introduced by Conway himself, with a bit of
contribution by Gardener who popularised it.

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xamuel
Very nice!

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
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.

~~~
xamuel
You're mixing up where the negation goes.

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](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...](http://www.combinatorics.org/ojs/index.php/eljc/article/view/v20i1p31)

~~~
jessaustin
Ack, sorry. For some reason my mind wasn't wrapping around the fact that you
can choose your configuration _before_ choosing your forbidden directions.

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stcredzero
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?

~~~
lmm
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?

~~~
stcredzero
The first thing that comes to mind, is that players would build glider guns
that would cause live cells to "fall into" collector cells to gather
resources. So it would be a farming/RTS game, except all of the crops and
weapons would be emergent from Conway's Life.

~~~
lmm
I think that's going to be unplayably difficult for anyone except serious
programmers, and it will be very difficult to design life structures that have
the behaviour you need to make the game fun, and even if you manage it you'll
have trouble running them fast enough to perform well. I mean best of luck if
you do do it, but it's going to be a real uphill struggle.

~~~
stcredzero
You're totally misunderstanding my proposal. (Either on purpose as a troll, or
you're just having a particularly obtuse day.)

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.

~~~
lmm
A glider gun is still incomprehensibly complex for non-programmers, I fear.

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.

~~~
stcredzero
_to the extent that it doesn 't it's not really life-based at all._

Obviously, because no MMOs have contrived mechanics, ever!

~~~
lmm
MMOs need two things: mechanics that make them fun as a game, and themeing
that will attract players. As far as I can see including a life aspect doesn't
help with either.

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iamwil
[https://niginsblog.wordpress.com/2016/03/07/new-spaceship-
sp...](https://niginsblog.wordpress.com/2016/03/07/new-spaceship-speed-in-
conways-game-of-life/)

This link has an animation of the c/10 spaceship.

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stephenitis
I'm confused about what I'm looking at... is this a pattern that emerges in
conways game of life?

~~~
stefs
it's a pattern that "moves forward", i.e. recreates itself at another
position.

~~~
Someone
At speed c/10, "one tenth of a cell in each iteration", or, better said: after
ten iterations, the pattern has moved one cell, but is otherwise unchanged.
That's why it is called a glider; it glides through the grid (a puffer stays
at its location and returns to its original snape after some time, but
periodically sends out gliders)

What's new here, apparently, is that this is the first glider discovered with
that speed. It also is surprisingly small.

~~~
mmanfrin
Really great explanation, thank you!

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tommoose
Is it just me or does the original frame look like Serenity (Firefly)? It's
movement is backwards though.

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Mauricio_
amazing

