Tuesday, March 27, 2007

Prometheus finalists announced

This year's Prometheus finalists have been announced. The links from the titles are to my reviews.

The finalists for Best Novel are: * Empire, by Orson Scott Card * The Ghost Brigades, by John Scalzi * Glasshouse, Charles Stross * Rainbows End, by Vernor Vinge * Harbingers, by F. Paul Wilson

And the finalists for Hall of Fame are: * A Clockwork Orange, a novel (1963) by Anthony Burgess * "As Easy as A.B.C.," short story (1912) by Rudyard Kipling * It Can't Happen Here, a novel (1936) by Sinclair Lewis * Animal Farm, a novel (1946) by George Orwell * The Lord of the Rings, a trilogy of novels (1954) by J.R.R. Tolkien * "True Names," a novella (1981) by Vernor Vinge

I haven't written reviews of any of the hall of fame nominees, though I've read them all. Perhaps that's a sign that I should read them again.

Saturday, March 24, 2007

Robert A. Heinlein and Spider Robinson: Variable Star

The author of Variable Star is listed as Robert Heinlein and Spider Robinson, but it's really a recently discovered outline by Heinlein that Robinson has turned into a novel. The story has a very anachronistic feel to it, with many heinleinian plot points (it appears to be set in Hienlein's Future History) but references to recent events and relatively modern mores.

I don't much care for stories with a reluctant hero, and Joel Johnston has to be dragged, kicking and screaming, through each of his life transitions. He's actually a fairly decent character in between, but the switch-overs are wrenching.

The story was a nominee for the Prometheus award, but wasn't chosen as a finalist. It doesn't have much to say about freedom or self-direction; it's not a cautionary tale; the governments are benign and consensual or required by circumstances (a 500 person starship has to have a captain and someone to keep the peace) and minimal, but in either case, neither something to fight against or to hold out as a model. The characters are pushed around by fate and circumstance.

The story takes so many hairpin turns that there's not much else I can say without spoiling the plot. Talking about anything after the first 50 pages would tell way too much about the most surprising development, and after that, things are pretty much pre-ordained other than the details. I'd rather read a real Heinlein juvenile, and make allowances for Heinlein's atavatistic viewpoint or a modern story by Robinson (with all the puns) than this mishmash.

Thursday, March 15, 2007

Would you Trade your Sense of Smell for a Longer Life?

Recent experiments on fruit flies undergoing Caloric Restriction seem to show that the effect of CR is reduced or eliminated if the flies are exposed to the odor of food (yeast in their case). That led to experiments in which the experimenters genetically eliminated the flies' ability to smell. They found a stronger contribution to lifespan from smelling the food than from how much the flies ate.

Would you give up your sense of smell if it meant living 50% longer? The question is only hypothetical at this point: replications in other species haven't been reported yet.

Saturday, March 10, 2007

F. Paul Wilson, Harbingers

F. Paul Wilson's Harbingers is a nominee for the Prometheus award. I understand the impulse to nominate the Repairman Jack novels for the Prometheus: Jack is a strong character who fights evil and eschews all contact with the government while living in New York City. His attitude toward self-help and antipathy to gun control also help his case. It's probably the fact that it's horror, and that both the cosmic bad guys and the cosmic okay guys are inscrutable that drives me away.

With this installment, I realized that there was another aspect that was bugging me. In the past 9 novels, little has changed about Jack's relationship to the two warring factions that are thoughtlessly interfering with Jack's life. Harbingers, on the other hand, contains several significant developments in that relationship. In fact, it reads like the second volume of a trilogy. Too bad it took Wilson 9 books (plus 6 others set in the Adversary world) to get us here.

But overall, I don't find the libertarian themes to predominate over the standard horror tropes. And inscrutable powers for whom we barely even qualify as pawns aren't much of a recommendation for a libertarian point of view.

In its defense, this book does have Jack standing up to the Ally after it attempts to take away what he most cherishes. But the negotiation ends with the Ally seeming to hint it won't hurt Jack's family for as long as he does what it wants. Not much of a recommendation.

Wednesday, March 07, 2007

Orson Scott Card: Empire

Orson Scott Card's Empire has been nominated for the Prometheus award. It stands a chance as a cautionary tale like Sinclair Lewis's It Can't Happen Here. The story covers a plot (with tentacles in the White House) to overthrow the government and bring about a left-wing coup. The action is intense, but the politics is strained. Like Lewis' novel, the point (as Card explains in an afterward) is to convince us that it wouldn't take much to turn our current heavily factionalized politics to open warfare.

The story reveals that far-left and far-right groups have been preparing plans in secret for years to take control of the government violently if it should become necessary (because the other side has gotten too much control.) The leftist radicals apparently have the advantage, since they have an extremely wealthy fanatical backer who has been funding the development of new high-tech weapons and staffing and training an army to use them. This part unfortunately reflects the fact that the backers of Card's project are game developers; the new weapons are several steps ahead of what the uniformed military has access to, but would play well on the video game consoles.

The viewpoint characters are sympathetic, well-trained special ops soldiers, and are patriotic to a fault. Their loyalty is to the nation and its legitimate leaders. The action is intense. But ultimately, the story falls short of being a cautionary tale. The motives of extremists on both side are hard to fathom; they want control of the levers of power to prevent the other sides extremists from doing something bad, but it's not clear what. After the conspirators take control of New York City and get sympathetic resolutions from a few state legislatures, they don't make any visible changes in anyone's lives.

At least Sinclair Lewis showed that the fascists who took over would have to suppress dissent brutally and ruthlessly in order to maintain control. In Card's novel, life goes on as before. At the end of the novel the viewpoint characters suspect the newly elected president of having helped orchestrate the entire coup in order to ensure popular support for his own election as a peacemaker. But they can't find any indication that he has dastardly designs to justify the conspiracy they are looking for.

The attempt at a coup and rebellion were short-lived, caused only a handful of deaths and a moderate amount of damage, and didn't have any impact on everyday life. As a cautionary tale, it's not much to worry about. If the protagonists hadn't done such a good job of protecting the nation, an extremist megalomaniac might have taken over the government, but Card's novel doesn't explain why that was something to worry about.

Tuesday, March 06, 2007

Conditional and Combinatorial Betting

After people have used Prediction Markets for a while and have gotten used to their ability to provide forecasts, they start thinking about different scenarios. Who would be the best Republican to face Clinton? How are the prospects for a market boom or crash effected by the winner of the election? How will poverty be affected by a proposed World Bank program? These kinds of questions can be posed in a number of ways using Prediction Markets. Markets can allow betting on conditional (if) or conjunctive (and) questions. Either one can be used to answer the what if questions, but they provide different choices to the bettors, and some make it easier for observers to decode the answers.

The easiest compound question to pose is a simple conjunction of two others. InTrade had separate markets in whether Bush would be reelected in 2004 ("BUSH"), and whether Osama bin Laden ("OSAMA") would be captured before the election. Justin Wolfers and Eric Zitzewitz asked InTrade to add a single combined contract that would pay off if both came true. Their paper, Experimental Political Betting Markets and the 2004 Election shows how the prices on these three contracts can be combined to show how one event would be likely to effect the other.

InTrade created three separate claims to cover combinations of the two base questions. They were "Bush wins election" (BUSH), "Osama is captured before the election" (OSAMA), and the combination: BUSH&OSAMA which would have paid out if both the others came true. Wolfers and Zitzewitz estimated the market's conditional probability by comparing the price of OSAMA with the price of BUSH&OSAMA. If the price levels were rational, the difference between the two prices had to equal the chance that Osama would be captured and Bush would not be reelected. Since the market price of BUSH&OSAMA was 91% as high as the price of Osama, they concluded that that represented the conditional probability. A weakness of this conclusion is that while investors and arbitrageurs have an incentive to ensure that the price of BUSH is correct relative to ~BUSH, (and OSAMA with respect to ~OSAMA), there's no bet that lets an arbitrageur exploit superior knowledge of the conditional probabilities.

Sometimes investors believe they know how one outcome will effect another, and want to bet directly on that linkage. If you were confident before the election that Osama's capture would raise the probability of Bush's reelection to 95% (above the level the the market prices implied), having the conjunctive bets didn't provide a bet that would have looked beneficial to you. You might think you could buy Bush&Osama (because you believe Bush's chances are improved if Osama is captured) and sell ~Bush&Osama (because this is the outcome your view says is least likely), but you'd lose both bets if Osama wasn't captured (which is an outcome your prediction doesn't specify.)

Conjunctive claims allow observers to deduce connections between claims, but since the investors aren't directly rewarded based on the conditional probabilities, they have little incentive to ensure that the implicit conditional probabilities reflect their understanding of the connections between the outcomes. In order to evaluate different proposals we have to look at what investors would spend up-front, and then compare the possible outcomes and how the investor's earnings change in each situation.

If Bush is a 60% favorite to be re-elected, and the market thinks there's only a 10% chance Osama will be captured before the election, the odds on the conjunctions might be:

 Bush reelectedBush defeated
Osama captured .09 .009
Osama free .5 .4

If you think Osama's capture would improve Bush's prospects to 95%, what should you buy or sell? Your prediction says that the ratio of Bush&Osama to ~Bush&Osama should be 19:1, but doesn't have anything to say about Bush&~Osama or ~Bush&~Osama. If you buy Bush&Osama and sell ~Bush&Osama, you can make the prices match your beliefs better, but you'll lose money if Osama isn't captured. In order to support conditional bets directly, market operators have to find ways to allow traders to buy positions without exposing themselves to risks due to the independent cases.

A contract that acts like a conditional bet directly (written as BUSH|OSAMA, pronounced as "Bush given Osama" or "Bush conditional on Osama") would pay off if Bush is elected, and return your investment if Osama bin Laden isn't captured. That gives investors the right incentive.

 Bush reelectedBush defeated
Osama capturedGain $1 Lose investment
Osama free Return investmentReturn investment

In order to support betting on conditional probabilities, the bets have to be able to return the investors' money in particular cases. I know of three detailed proposals that have this property. They are: betting on arbitrary boolean expressions, representing the complete cross-product of possible outcomes (providing a complete set of Arrow-Debreu securities), and using the independent claim as currency for purchasing the dependent claim. There are two additional suggestions that might work, but haven't been written down in sufficient detail to be sure.

Robin described and implemented Combinatorial Information Markets which represent probabilities and traders assets explicitly for all possible combinations of outcomes. Fortnow, Kilian, Pennock, and Wellman described how you might try to support bets on arbitrary boolean combinations of conditions. Their conclusion seemed to be that solving the general problem would be computationally infeasible. They didn't describe how to address the problems they found, but I think it's possible that a market that supported only binary combinations could be designed. And finally, Peter McCluskey built (and released as open source) USIFEX in 1999. It allows the user to use the coupons of the independent event as the currency. This combination allows traders to express conditionals directly. Unfortunately, that system didn't attract a user base quickly enough, and Peter stopped development soon after the initial release.

For an article on Decision Markets written in 1999, Robin Hanson suggested creating markets using assets that pay off in "units of A if B passes" (and "... if B doesn't pass."), and allow traders to trade the assets for each other. The price of A|B in terms of B (which can be built from component assets) expresses the conditional bet. Robin didn't explain how to set up a market in which people trade assets for assets and didn't describe how to let the users see how various combination bets would express the conditional claims they might have been interested in. (This is the first of the two incomplete suggestions.)

Robin's Combinatorial Information Market design uses a complex internal representation and can support arbitrary conditional bets. He built a prototype implementation that allows the user to explore these conditionals by choosing assumptions, and then adjusting probabilities in the resulting hypothetical situations. I wrote a prototype of my own in E. Neither prototype is more than a proof-of-concept that the institution works, and neither has been operated for any general market. The strength of this approach is that users can express conditional connections between arbitrary claims; this aspect has been shown to be effective in a laboratory experiment. Robin ran tests of this market after he proposed its use for PAM, and there were apparently no problems in running it with 6 traders estimating all outcome combinations for 8 events. The glaring weakness is that it doesn't scale well. It's not clear how to build a version that would work even with a market with dozens of questions and hundreds of users. I'll describe this market in more detail in a future post in this series.

Peter McCluskey built USIFEX in 1999. It works quite differently and doesn't seem to have the performance problems of the other proposals. The primary idea for supporting conditional trading is that you buy units of A|B using units of B as currency when betting on a conditional question. The effect is that when buying A|B, you end up with coupons of ~B as part of the purchase, and that's what ensures you'll be repaid if the independent event doesn't occur. USIFEX is open source, but it hasn't been maintained since it was released in 2000. The code was resurrected for use in the Swiss MarMix exchange, (AFAICT without making any use of the conditional betting features). The biggest weakness of Peter's approach, as I recall, was that it would have taken a lot of users to ensure that the conditional markets weren't extremely thin. A longer description of USIFEX is also in the works.

Todd Proebsting built an implementation of the Hanson design that works without conditionals. Dave Pennock wrote up a description of Todd's approach, focused on the Market maker. I intend to describe the implications of Todd's approach for betting on conditionals in a future post. (This is the second incomplete suggestion.) I think it might be straightforward to extend Todd's approach to support conditional betting without running into the exponential growth of Robin's solution. The drawback is that the market operator has to separately capitalize and enable every conditional question that you want the system to support, while Robin's approach enables all of them by default. It's also possible that Zocalo Open Source Prediction Market software would be compatible with this approach, where it's clear that Zocalo would require substantial modification to support the Hanson proposal.

Other Articles in this series

Thursday, March 01, 2007

Robert Pape: Dying to Win

Dying To Win , by Robert Pape, makes a reasonable case that suicide terrorism is primarily used by groups that perceive themselves to be oppressed in their home country by a powerful democratically governed foreign invader (usually with a different religion). The goals and intentions of the occupier don't actually matter very much, as long as the defenders feel that they don't have control, and can use the religious difference to demonize the invader. Pape marshals a considerable body of evidence to show that conventional wisdom is wrong: the terrorists play up religious differences, but aren't motivated by religion; the individual terrorists aren't poor or suicidal; and suicide terrorism is used against democratic countries (the goal is to convince the voters that the occupation isn't worth the cost.)

The book's thesis only explains a portion of what is going on in Iraq today. As far as I can tell, suicide terrorism aimed at the occupying powers is less than half of the violence currently occurring in that country; the rest is sectarian. Pape's thesis doesn't explain why roughly equal factions would use suicide terror against one another in an internal conflict. But I think the explanation of the attacks against foreigners holds up well. Unfortunately, only part of the terrorists' message to America is getting through to the American public.

The public understands that American soldiers are being targeted, but all the internecine violence obscures the message about foreign occupiers. Since some of the local factions are clearly more interested in a battle for control of the country after we leave, the violence against foreign troops looks like part of a strategy to maintain disorder. Major media haven't help Al Queda spread the message that all they want is for the foreigners to leave. Even if they had, the internal violence gives some Americans a reason to want to persevere, so we can help stabilize the country we destabilized.

Pape argues that the only responses to suicide terrorism that have stopped it in the past have been acceding to their demands (withdrawal) and ruthless violence against the terrorists and their community. He argues that one of the reasons this strategy is only used against democracies is that they are seldom willing to be sufficiently ruthless.

I wonder whether it wouldn't have been useful in this context if we had spent some effort ensuring that the history of the American occupation of Germany and Japan after WWII was heard in the Middle East. Those countries didn't lose their national identity; they got a lot of help rebuilding; and they came out of it much stronger than they went in. It may be too late for this message to be spread in the Arab world, where everything we say now is treated as propaganda.

Pape's policy recommendation is to remove active troops from the Middle East, while leaving enough deployed in nearby positions so that we could respond rapidly to new threats. This, unfortunately doesn't address the current situation in Iraq; leaving the country now would give the violent local factions unfettered ability to continue their mutual pogroms. If that isn't the kind of event we would expect to respond to from the off-shore position he recommends, what would be?

For the most part, the book was reasonably even-handed, given Pape's apparent prejudices, which he showed once or twice. He speaks of an American "Policy [...] to conquer Muslim countries" on pages 6 and 241, but otherwise sticks to analysis based on an extensive database of all known suicide terror incidents he has compiled at the University of Chicago. The last, short, chapter giving his policy recommendations is clearly separate, and readers can individually evaluate its merits.