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Feb. 8th, 2016 @ 11:03 am Robbi game working on Android!
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I got my robot-programming game to run on Android! I knew it shouldn't be *that* difficult, but it's really magical seeing something I wrote running on a platform I never expected to run on.

I haven't done any more to the game since last year, so it's not really *playable*, but it runs and you can interact with it.

I used kivy as the UI framework for a python game, because it advertised being able to compile to android, and I wanted to learn more python more than I wanted to learn java. So I developed the program on the PC, using kivy for graphics and mouse events (which later become touch/drag events on a touchscreen).

And then after several false starts, I downloaded a VM set up to the do the "build to android" step with buildozer, updated buildozer to the latest version, copied my source to the VM, I already had generated a buildozer.spec file, and it all just worked -- I got an apk, I opened it from dropbox on android, and there was my game running.

Gotchas, I don't expect anyone to try this with my instructions, but in case you do, things I didn't find obvious: to share a folder with the VM, you need to add your user account to a "can see shared folders" usergroup; buildozer can fail to work on a shared folder, copy the files to a local directory on the VM; you should be able to install the android dev kit etc with or without buildozer, but I couldn't get it to work.

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Feb. 7th, 2016 @ 11:28 am JourneyQuest
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JourneyQuest is a web video series by Zombie Orpheus, who are the team who made The Gamers. It was really funny!

Unlike The Gamers, it takes place solely in the fantasy world, there's no humour in the way real-world players choose to play characters, which I really loved. But there's a lot less "ha ha, roleplayers are often all men and make sexist jokes" humour, which is good!

It starts with a simple four-person adventuring party seeking the legendary "Sword of Stabbing", but spirals out from there as they become unexpectedly destined to succeed, the plot tangles up with the orcs they met, the bardic college track them to try to ballard the story... My favourite characters are probably, Perf the hapless wizard who always ends up in the centre of things, and the clever orc who always appears put upon as the involuntary voice of reason.

You can watch series 1 & 2 here: http://zombieorpheus.com/shows/journeyquest/

And there's a kickstarter for #3 here.

It does leave me with that feeling of "great characters, great setting, great concept, but now I've moved beyond just laughing at them and I want to know WHAT HAPPENS. Move the plot along already". But that's basically "it's fun, but not very long" which is hard to argue with.

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Feb. 7th, 2016 @ 11:18 am My Real Children, Jo Walton
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Unsurprisingly, this is really good! It's the whole story of Patricia's life, told in flashback from her nursing home where she is losing her memory. Except that it's actually two lives, in two parallel worlds, which combines badly with losing her memory anyway.

It covers a lot of the social and geopolitical themes of the second half of the 20th century. Nucelar armament. Moonbases. AIDS. Feminism, in several models. Gay and poly relationships.

It's less depressing than I feared: yes, people die, including the protagonist soon, but that's unavoidable for a whole life, to me, the message felt more like "all lives have redeeming features".

The two bits I found most difficult were reading about her marriage in one world to her young love, who, once she's a wife, completely dismisses her as a person, expecting her to do everything, but failing to respect her opinion or competence at anything :(

And when she went into the home and couldn't take her Mac, which she used for keeping notes, and looking up words she'd forgotten, and realised she was going to sever completely the connection a normal life :(

But in both worlds, she has lovely children who become people, and grow up, and it's really touching.

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Feb. 7th, 2016 @ 12:38 am Relativity: Roll to Disbelieve
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I've been trying to get this straight in my mind by asking what the world would look like if relativity wasn't true.

It's probably true that "everywhere in the universe is the same time and everything has speed and position that's the same wherever you measure it from" is simpler and more natural than "the time between two events and the distance between two objects depends how fast you're going". But when you dig into it, it doesn't really hold together.

Lots of explanations try to tell you the details about how the world is different with relativity than if it was all newtonian. I don't understand it well enough to talk about how. But rather than glossing it over, I'd rather tackle head on, why I should think something weird is going on. It's like, explaining calculus without understanding what problems there are that are worth solving, and are hard to solve, but trivial with calculus, just feels like a pointless arbitrary set of rules. But once you get what it's for, you understand it in an equally important way as if you know how to do it.

I think the key question is, how fast does light move? Lots of people know, c, or 300 million m/s, or 1 foot per nanosecond. But relative to whom? When we describe speeds, we normally mean "relative to the Earth's surface", or "to the Sun" for things in the solar system. That's normally obvious, but it's only obvious because it's the same -- you have to pick the right scale, or else you say you can jog at the speed the earth orbits.

What are the possible answers?

1. Like normal objects, light travels at the speed of the object that emitted it, plus c. If you throw a ball on a train, within the train, it travels at the speed of your throw, but relative to the ground, it travels at that speed plus the speed of the train.

2. Like waves, it travels at c relative to a fixed stationary... something. If you drop a big rock into the sea from a fast plane, the waves spread outward at the same speed, however fast the plane is going. If you have a siren on a vehicle, the sound travels at the same speed in the air, however fast the vehicle is going (as you can tell, because if you fast enough you catch up with the sound -- a sonic boom).

3. You measure light as travelling at c, and everyone else measures light travelling at c, even if you're going in different directions at hundreds of thousands of miles per hour. Yes, this is ridiculous, how can different people measure the same thing and get different results? But -- we've measured light in all sorts of ways, and whatever we do we ALWAYS see it going at c, just like maxwell's equations say it should. (Well, slower in atmosphere, but a known amount.) I think if relativity were explained like this, "we measure light going at the same speed everywhere, how come?" it would make more sense than explaining the historical order.

4. Light travels at c relative to the nearest large planet, slowing down or speeding up as it moves from the neighbourhood of one planet to another.

Well, which makes sense? #1 sounds plausible. But we receive the light from stars, and can measure its speed. Stars go VERY fast, so those light beams should be at very different speeds depending what star it came from. But no, they all go at c.

#2 also sounds plausible to start with. But where is this invisible stationary air or water or something? The earth orbits the sun, and the sun orbits the galaxy, etc, etc, at very very high speeds, so we should never be stationary relative to the medium. Which means if you measure the speed of light in the direction of the earth's orbit, and perpendicular to that, you should get very very different answers. But no, the speed is always measured at c.

Alternatively, this medium is always exactly aligned with the Earth specifically. That should sound dodgy. From an orbital mechanics perspective the earth doesn't look at all special. It's hard to disprove this until you get to the fancier experiments in the footnotes, but it should sound like "a bodge", not "the answer".Ironically, of the three wrong explanations, this comes really close -- it works perfectly, it's just that in the real world, it's not just the Earth that has a special "stationary" aether, every point/velocity in the universe does.

What about #4? Again, this should sound dodgy, but is hard to actually disprove. Until relativity was accepted, this was a good theory, that the earth "dragged" the invisible aether with it, so it was always moving at the same speed. I can't remember what disproves this, but it shouldn't sound good. You'd also expect weird effects different to relativity as light moves near other planets and stars. And maybe weird red/blue shift as light moves from one speed of aether to another.

That leaves #3. Which is very counter-intuitive, but actually predicts something very like what we see -- both "at everyday speeds, everything acts like newtonian mechanics" and "but for everyone wherever they are, maxwells equations and the speed of light work exactly the same." It wasn't obvious that those would conflict, but they do, unless you accept relativity.


I can't remember all the relevant experiments. A big one is https://en.wikipedia.org/wiki/Michelson%E2%80%93Morley_experiment which measures the speed of light in the direction of the Earth's orbit, and perpendicular to that, and discovers they're the same. It doesn't "measure the speed", by waiting until the light gets from A to B, rather, it sends light down the two paths and then adjusts the path lengths until you get an interference pattern showing they're exactly in sync. Which is when the paths are exactly the same. Every other "measure the speed" is similar.

If there's holes in the above, are there *other* experiments that suggest the universe isn't straight-forwardly Newtonian? Yes, lots, wikipedia has a big list, although not all easy to understand. My favourites are:

* Produce light of a specific frequency (with some crystal that has a very precise frequency response?) Check that's it's re-absorbed by that same crystal. Yes, if the apparatus is horizontal. No, if its vertical. Why does that make a difference? In a non-relativity world, Newtonian gravity and Maxwell's electromagnetism should be completely separate. But relativity says, moving to a different height in a gravitational field will change the energy, and hence frequency, in the light -- which is does.

* The incredibly precise times from GPS satellites needing to be tuned to account for general relativity.

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Jan. 27th, 2016 @ 03:21 pm Things to see in Amsterdam
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Last minute suggestions for things to see in Amsterdam?

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Jan. 27th, 2016 @ 02:48 pm Threes speed dating algorithm
My latest thought is, I expect to be able to get a close-to-optimal matching for N=2n or 2n+1 people in n rounds of N/3 groups of 3, when N is a multiple of 3.

But if we have exactly enough groups that each person meets each other, that relies on each group of 3 in each round, all 3 pairs not having met before. So maybe the right algorithm is for each round, "randomly generate groups of three where all 3 pairs haven't met before, made of people not already placed this round". And as soon as you can't, back up a round or more and try again. That guarantees permuting when we need to, as soon as we need to. And I sort of hope that when things work in the middle, they'll "just work" for the last few rounds but I don't know if they will.

However, I'm away until Sunday so I probably won't have a chance to try it. Anyone else interested enough to have a go?

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Jan. 25th, 2016 @ 06:10 pm Gay speed dating algorithm, the next-biggest hammer
Having failed to use the biggest hammer ("ask the internet if anyone can think of a general mathematical solution"), I tried the next-biggest, brute-force.

I wrote a program which divides people into random matchings, and then switches matches which are over- or -under represented. I'm not quite sure what sort of "random switching" is best, I hoped to just get lucky.

The first effort found a version for 9 people easily, but didn't find one any larger than that. The second was about the same. That's where I am now. I can describe the shuffling in detail if anyone is interested or thinks they might have any suggestions.

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Jan. 25th, 2016 @ 05:58 pm Dwarf University v2.0

OK, after mulling over comments several people made at games evening, I made several changes to my dice game.

I changed the somewhat nebulous "two pairs of dice" concept to be that, on your turn, you roll four dice, and then may spend a pair of dice, either for 1 money, or to do an action square at the sum of the dice once for each meeple you have. And you may repeat as long as you have dice. So to start with, you have two dice, but some abilities let you roll another dice as well, or reclaim an already-spent dice. One extra dice means more choice, two extra dice mean another action.

It also removes a lot of the ambiguity, because now you can clearly say "a spent dice" or whatever.

I rewrote all the abilities to work in that way, and increased costs slightly to match the fact you get $1 per pair of dice, not $1 per turn.

And as you see, I wrote up a .pdf so other people can see, and can print out and play it if they want. I think the turn order is enough info to play in theory, although I think it'd be confusing to try without having seen it played first.

The new abilities are COMPLETELY untested. One of the first things I want to do is simply test the "spending dice" concept at all and see, does it give more choice in the right ways, is it intuitive, and does it maintain balance between actions?

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Jan. 25th, 2016 @ 01:39 pm Hudson Hawk, Steven Universe
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Hudson Hawk

A film with Bruce Willis as a once-famous cat burglar just getting out of jail, blackmailed into taking several Leonardo Da Vinci related heists. I once played a very good 8-bit platform game based on it, which captured the feel of catburgling quite well for the time. It was one of the first games I actually finished, which was really exciting.

A few bits are really fun, when they sing the same song to time themselves and keep themselves in sync as they go around different parts of the building. And the introduction of the gang with candy-bar codenames. But then it descends from heist movie into slapstick action movie and I mostly lose interest.

Steven Universe

One of the animated children's TV shows which lots and lots of people have been very excited by recently. The crystal gems are three gemstone-themed alien people who protect the earth from various monsters, aided by half-human half-gem Steven.

A lot of people praise the handling of emotional themes, eg. Greta Christina on episode 5: http://freethoughtblogs.com/greta/2015/12/10/steven-universe-episode-5-frybo/ on how one of Steven's friends disappoints his father. It's generally a good role model, having lots of examples of flawed people who are not all good or bad and easily-accessible examples of complicated emotional stuff.

The episodes mostly about some of the humans don't hit my emotions as hard as they do other people, but I also liked a lot else about it.

The gems are all aliens who, it seems, don't have two different sexes, but are all coded as "female" in the show, whatever their role in society. Which I think works very well, considering the number shows which have used "male" as if it were equivalent to "default, no marked gender".

Steven's emotional maturity and skill with his gem powers are shown growing really realistically. It's not always a straightforward "he learns how to do this, and then can do it henceforth", but there's a clear sequence of "he can't do this", "he can do this some of the time and is excited when it works", "he makes a lot of effort and isn't sure if he'll succeed", and finally "he does this fairly reliably". I think, if you watched episodes slightly out of order, it would still work nearly as well, but there's a definite benefit to watching the whole series mostly in order.

And in many ways, the "struggling to learn how to do it" is more realistic than having a "one episode where he learns it". It's very moving to watch Steven progress from automatically being left at home during missions, to being automatically included in the team.

The worldbuilding is great. The early episodes do a very good job of painting the general situation, the gems, raising Steven, protecting the world, etc. But as we slowly learn more, learning about the gems original homeworld, and where the monsters come from, and the history of Steven's mother, we learn a richer story that doesn't contradict what we learned. And it's all sufficiently consistent, it's possible to speculate and be correct, and things introduced in later episodes don't make nonsense of the earlier episodes where they weren't established yet.

I'd rather have MORE of that, but then, it's not aimed primarily at me.

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Jan. 21st, 2016 @ 06:12 pm Speed-dating algorithm update
Ah! After some more introspecting on the right terms to google for, I found: https://en.wikipedia.org/wiki/Round-robin_tournament#Scheduling_algorithm

That describes a simple algorithm which works for pairing any number of people into 2s, making sure each meets each other. I hoped there must be one but hadn't realised how simple it was. AFAICT that's minimal (inserting an extra empty place if you start with an odd number, which is unavoidable), making 2x or 2x-1 people meet in 2x-1 rounds, with x pairs per round.

There are a lot of more complicated systems which aim to do things like make an even balance of "home" and "away" games which don't apply here.

However, that doesn't yet obviously generalise to meeting in groups of three (with the aim of meeting each person once, not each possible combination of three). I wonder if there's something to be learned from bridge rotations, which aim to pair each team with each other team, and also with a unique board?

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