Monthly Archives: February 2015

On tafl

While I attempt to dream up suitable procurement challenges for Parvusimperator, who is much harder to challenge than I am, I have some side projects in flight. One of those is a computer implementation of tafl.

Tafl is an Old Norse board game. The name means ‘table’, and the game and its variants are also known by some others: hnefatafl (King’s Table, to my best guess), brandubh, tablut, alea evangelii, ard ri, and likely some I’m forgetting. It is mainly notable for being the best-developed asymmetric abstract strategy game of which I am aware. Common across all the varians is the central goal: one side, the king’s side, starts in the center of the board. Its goal is to get its king to escape. The other side, the besieging side, plays to prevent the king from escaping. The king escapes on edge spaces in some variants, and on corner spaces in others.

Taflmen are moved like the rook in chess, orthogonally, any number of spaces. Captures are made by surrounding opposing taflmen on two sides, though some variants require that the king be surrounded by four opposing taflmen to be captured, and others do not allow the king to take part in captures.

Some modern variants introduce innovations aimed at a more balanced game, or one less likely to stalemate: pieces in a line on a board edge can be captured by lining up your own pieces opposite them and surrounding them to the sides, or the king can escape by means of a similar formation, if he is able to move inside the surrounding formation. Other modern variants go even further from the original rules, introducing pieces which can jump to move or jump to capture, and the ‘berserker rule’: a piece which makes a capture can move repeatedly, so long as each subsequent move also makes a capture. (That one is going to be a huge pain to implement. Just saying.)

Anyway, besides its obscurity and its Viking flavor, I find two other things to like about tafl games: first, the unchartedness of the territory. Tafl is still an enthusiast community, and although it seems to be growing, research into the game is still in its infancy. It’s a chance to break some new ground in human understanding, a compelling reason to work on it.

The second reason is the probable computational complexity of tafl games. Though the rules are simpler than those of chess, it’s my suspicion that, in terms of raw possible games and average branching factor, tafl is a harder game to model than chess. Consider: concretely, taflmen move as freely as the second tier of chess pieces (the rooks and bishops), and the tafl board is bigger (attested variants range from 7×7 to 17×17 or 19×19, depending on your interpretation of the rules). Qualitatively, it feels to me like tafl is a busier game: the capture rules mean that it’s more difficult to make captures while keeping strong positions, and the escape/surround duality in objectives means that material advantage is, to a certain point, less important. Pinning a piece in place so that a piece behind it can’t deliver an attack is fundamental to chess tactics, but two taflmen in the same vicinity build upon each other, and their interchangeability means that sacrificing one taflman so that another can move into a better position requires much less care than chess tactics do.

I suppose, speaking in the most general terms, chess between evenly-matched players is a game of materiel before a game of position: gains in material advantage are easily parlayed into gains in positional advantage, because it’s easier to fix an opponent’s powerful pieces in place relative to tafl. Tafl between evenly-matched players is a game of position before materiel. It isn’t uncommon to see high-level tafl players decline to take ‘freebie captures’—when the opponent places a piece into a position where it can be captured without retaliation—because a small material gain is not worth losing a turn in the race for position elsewhere on the board.

Anyway, that’s all I have for today. As I get OpenTafl more ready for a release, I intend to go into more specifics about its variations, its strategy, and my implementation of its more curious features and work toward a reasonable AI. I’ll see you then. (Or probably before then, when I tell you which things I’ve chosen for Parvusimperator’s unseemly gauntlet-throwing.)

2015 projects and series

Now that we’re a month into the New Year, it’s time to go on record with some plans and details for 2015. Below, in no particular order, are the major non-writing things I and Many Words collaborators and non-posting friends will be working on this year.

The Nivkh-Quechua cognate hunt
A friend of mine has been looking for and finding a surprising number of cognates between Nivkh, a Siberian language, and Quechua, a South American language. Since his dictionary source material for Nivkh is primarily in Russian, I’m lending him my Russian experience to help out.

Tafl, the Old Norse board game, has long been an object of fascination to me. It’s also a very poorly understood game. One of my projects this year is to finish a computer representation of several variants of the game, so that I and a friend of mine can investigate it more deeply than has been done to date. Also because it’s cool and there isn’t a good way to play with friends and I need to fix that.

Skypirates theme
Parvusimperator and I enjoy our shared Skypirates universe a lot, but we’d like to do some more world design in places we haven’t looked at much. We’ll have some details for you on China, Imperial Japan, and Nazi Germany, for sure, since Parvusimperator is doing most of the work there, along with Corregidor (the Tortuga of the Far East). I’ll probably be tackling the Australian Colonies, the American West Coast nation of Pacifica, and Tortuga (the Corregidor of the West).

The Casino Job
Parvusimperator is also planning on actually putting out a story in the Skypirates universe, featuring his own crew and his own zep. I won’t spoil anything besides the title.

An unspecified app project
Since my friend and I are slow workers, I’m not going to say anything about this until it’s nearly ready for prime time.

Projekt Archangel
I’m planning on modernizing a Mosin-Nagant rifle (don’t worry, collectors, there are tens of millions of them, and I have one to keep original) toward the end of this year. Pictures and build details when they happen.

Picking up the gauntlet
I guess I have to answer the challenges Parvusimperator threw down. Let no man say I am a poltroon.

Throwing down the gauntlet
The other half of the above.

On the Throwing of Gauntlets


Come out, Fishbreath!

I expect and demand to see procurement postings for the following four big-ticket items:
–An Infantry Carbine, complete with reasoning on choice of caliber and overall configuration (conventional or bullpup)
–A Sidearm
–A General Purpose, Medium-sized Utility Helicopter
–An Attack Helicopter

Pick up the gauntlet and respond if you dare, or be forever known as a poltroon and lazy shirker!

Procurement 4D: Lightning Squalls

Richard Bong’s Ghost, I appear to have left out the F-35A from my procurement discussions. How could I have?

To be honest, I came into this not liking the Lightning II at all. It’s heavy, ugly, has relatively poor handling characteristics on paper, and is riding a massive hype machine. Oh, and it’s really, really expensive. It’s just not what I would have considered. But, I can’t have a discussion of modern fighter procurement without at least touching on it. And that means admitting that the F-35A is about as desirable as an independently-wealthy supermodel in a dating show. Which is to say, unfathomably desirable. I have great respect for the Israeli air force, and they’re on The List. I also respect the South Korean Air Force, which is also in a threatening location, and they cheated on the requirements (no really, they rewrote the requirements) just so they could get a piece of that Joint Strike Action. Neither of these air forces were part of the original partnership group, so they’re not trying to preserve local jobs. And despite the sticker price, Singapore calls it ‘economical.’ So, what am I missing? Well, a classified-level briefing and some fancy mathematical models of air combat, certainly. But beyond that, it’s probably important to figure out why the F-35A is so desirable to the world’s air forces. So let’s take a closer look at the Pride of Fair Columbia.

The F-35A is stealthy, and it’s in production now. Where else can you get both of those? Go ahead, look around, make a few calls. I’ll wait.
Yeah, that’s what I thought. Right there is something that you can get nowhere else without violating our rules. Stealth is cool. Is it as stealthy as a B-2A Spirit? No, but the Lightning II isn’t a big heavy bomber either. Its stealth is X-band optimized, and with internal weapons carriage its radar signature can’t be beat in its class, unless you want to look at prototypes or things that the US Congress says You Can’t Have. And unlike some people, I’ll hold myself to those rules. If you want stealth this is the only game in town. And you know the stealth is going to work, because Lockheed Martin has plenty of experience with those materials and that design. Which reminds me, just in case you’re not sold on this whole ‘stealth’ thing, go blow the dust off your VCR and put in your CNN Archive tapes from Gulf War I. Pretty cool. Operating with impunity over the heart of one of the premier air defense systems at the time. Stealth is a massive gain for survivability in the face of modern, integrated air defense systems.

I know what you’re thinking though. First, you’re going to gripe about the F-117A shot down over Serbia. And yeah, okay, you got me. Stealth isn’t perfect, and I never claimed that it was. This is not a cloaking device. It just makes it a lot harder to detect on radar. And in Serbia we’re talking about a really clever piece of surface to air missile operation, plus somewhat sloppy route planning package on an aircraft that had no systems to warn it of an incoming missile. Credit where it’s due, that was a hell of a shot. But it’s not really an indictment of stealth technology as worthless. We still have a phenomenal sortie:loss ratio here. The next obvious gripe is that the F-35A can only carry two JDAMs internally (with two AMRAAMs, or six AMRAAMs without the bombs). And it’s true, that’s not the greatest loadout ever. But we need to be precise–that’s the sneaky loadout. Two 2,000-lbs-class precision guided munitions is exactly what the F-117A carried. It can carry more in low-threat environments, when we’re less worried about our radar signature. But, unlike an F-16 (say), the F-35 can also sneak in and blow stuff up like an F-117. Which was pretty freaking useful despite its smallish loadout. And the Lightning II has really good range performance with only internal stores too.

But there’s more to the F-35 than just the stealth option. Even if we load up all of the external stores, we still have all of the electrics. And the electrics and sensors on the F-35 are second to none. On the front aspect, the F-35’s IRST is basically a built-in Sniper XR targeting pod, and that model is top of the line. So it’s got all of those features without needing to blow a hardpoint on a TGP. That’s not all though. There are six IR sensors around the airframe, arranged for all-around, always-on coverage. You read that right. Always-on. The computers integrate all this for the pilot to identify and track things all around him. When he turns his head, he sees what the appropriate sensor sees, right in his helmet, but the rest of the sensors are still feeding the computer data. No sensor panning. With the computer’s sensor fusion, this gives him the best situational awareness anywhere. Infrared and radar data is combined for identification and tracking purposes. The distributed IR system gives not only awesome infrared searching and tracking, but also missile approach warning, all in one system. But that’s not all. The F-35A has one of the top radars in the world, the AN/APG-81. It may not have the raw power of the IRBIS-E, but it’s cleverer, with fancy LPI modes and built-in electronic warfare capabilities. It’s got everything you’d want for reconnaissance too, with multiple ground moving target detection and tracking, high resolution mapping, and combat identification modes. But wait, it gets better. The F-35A has an integrated electronic warfare suite. It can provide all the SAM radar ranging data and jamming support that it might need, no bulky pods or separate EW aircraft needed. The F-35A has a datalink as well. While it’s not the first fighter to have one (cf. Fishbreath’s post on the Gripen), it has a particularly good one with some compelling features. Specifically, it can datalink to things that aren’t aircraft, such as long range surface to air missiles in order to provide guidance data. It’s like having an extra wingman when you’re fighting near friendly ground forces. Call it a home-field advantage.

Okay, so the F-35 has a lot of really compelling features that you can’t get in any other fighter. Awesome. But what about handling? Well, it gets some help from the internal stores. Anything inside clearly creates no drag. According to many sources, the F-35A with internal stores handles about like an F-16 with a similar weapons load. Now, there are a whole bunch of caveats here, but since I’m not about to try to make a fancy 3D comparative graph of performance data on these two planes, so I’ll take them at their word of “Roughly F-16-grade handling”, and it ought to be good enough for the purposes of this argument. Is ‘Roughly F-16-grade handling” enough? While the F-16’s handling is pretty darn good, the Rafale’s is better, as is that of the Sukhoi Su-35S, the most likely near-term opponent (anything more advanced isn’t in production yet, so it’s a lot harder to predict what the production version will be capable of). So what does that better handling get you? To know this, it helps to know why we bothered going for handling in the first place. At the start of the “Fourth Generation” of jet fighter design, a missile could reliably engage a bogey regardless of its aspect. But the missile had a limited envelope, which is to say the zone in which it could see a target to engage it. Call this envelope a roughly 60-degree cone with the apex at the nose of the launching fighter. Better maneuverability meant that you could get your cone on the other guy first, and so you got first shot. Does this ensure a kill? No, because PK is never one. But it helps, because it usually gets the other guy to go defensive, which meant he had something better to do than try to kill you. Getting first shot is always better. Now, the F-35’s designers say that given the fancy sensor fusion and all-aspect sensors, as well as missiles that can engage a target on any relative bearing, we don’t really need all that agility. You’ve got first shot if you can see him and if he’s close enough. You also get the stealth on your side, to reduce your radar signature, and thus the range at which the other guy can lock you up and get his shot off. All points in the Lightning II’s favor. And there’s the aforementioned integrated electronic warfare, to make an opponent’s life worse.

But what if we’re wrong? What if the Pentagon and Lockheed got their vision of the future wrong? Well, we’d still have all the nifty strike and EW support aspects that I mentioned previously. As for the dogfights, let’s look at some history. The F-4 Phantom II is, on paper, rather a poor dogfighter. It’s big and doesn’t have the handling of it’s Russian contemporaries. In Viet Nam, we saw that it’s vaunted AIM-7 Sparrow missiles weren’t very good at their jobs. And, since the USAF and USN didn’t train pilots in dogfighting, they weren’t very good at it. So the Americans got their butts handed to them by the Vietnamese. But then, the Americans decided that something had to change. So the TOPGUN program and the Red Flag exercises were created, to train pilots in dogfighting. Even dogfighting with opponents who flew different planes, with different strengths and weaknesses than a pilot’s own. And the pilot training emphasis meant that afterwards the Americans gained a favorable kill ratio against their Vietnamese opponents. Similar results happened in the Arab-Israeli wars, where superior training on the part of the Israeli Air Force made up for any shortcomings in their fighters. Looking even further back, General Chennault’s Flying Tigers had an impressive kill:loss ratio against Japanese pilots in China, despite flying aircraft that looked terribly inferior on paper. So, if we do our part with a good training program, we can make up for any shortcomings that a fighter might have. But to be fair, we don’t know these shortcomings yet.

With all that said, the advantages of the Lightning II outweigh the disadvantages of lower payload and less agility when compared to the Rafale. We’ll suck up “good enough” 4th gen fighter handling (or better depending on which reports you read) for the avionics, situational awareness aids, and stealth features. Stealth provides an extra option for the Lightning II; if we choose not to use it on a given mission we get a F-16/F/A-18 with stupidly good avionics and integrated ECM. That’s a fine package. Also, being American, the F-35 is dominant in the 4th dimension of aircraft design (i.e. the political one) as well.

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