I found this article a few years ago when I was looking at heuristics. I can't find the article text online anywhere anymore. I don't want the article to get lost. :( So here it is. I don't care if you upvote or downvote, just don't delete it. This article deserves to be read.
Eurisko, The Computer With A Mind Of Its Own
George Johnson
On the July 4 weekend of 1981, while many Americans were preoccupied with barbecues or fireworks displays, players of an immensely complex, futuristic war game called Traveller gathered in San Mateo, California, to pick a national champion. Guided by hundreds of pages of design rules and equipment specifications, players calculate how to build a fleet of ships that will defeat all enemies without exceeding an imaginary defense budget of one trillion credits.
To design just one vessel, some fifty factors must be taken into account: how thick to make the armor, how much fuel to carry, what type of weapons, engines, and computer guidance system to use. Each decision is a tradeoff: a powerful engine will make a ship faster, but it might require carrying more fuel; increased armor provides protection but adds weight and reduces maneuverability.
Since a fleet may have as many as 100 ships—exactly how many is one more question to decide—the number of ways that variables can be juxtaposed is overwhelming, even for a digital computer. Mechanically generating and testing every possible fleet configuration might, of course, eventually produce a winner, but most of the computer’s time would be spent blindly considering designs that are nonsense. Exploring Traveller’s vast “search space,” as mathematicians call it, require the ability to learn from experience, developing heuristics—rules of thumb—about which paths are most likely to yield reasonable solutions.
In 1981, Eurisko, a computer program that arguably displays the rudiments of such skills, easily won the Traveller tournament, becoming the top-ranked player in the United States and an honorary Admiral in the Traveller navy. Eurisko had designed its fleet according to principles it discovered itself—with some help from its inventor, Douglas B. Lenat, an assistant professor in Stanford University’s artificial-intelligence program.
“I never did actually play Traveller by hand,” Lenat said, three years later. “I don’t think I even watched anybody play it. I simply talked to people about it and then had the program go off and design a fleet…When I went into the tournament that was the first time that I had ever played the game.”
Eurisko’s fleet was so obviously superior to those of its human opponents that most of them surrendered after the first few minutes of battle; one resigned without firing a shot.
Eurisko makes its discoveries by starting with a set of elementary concepts, given to it by a human programmer. Then, through a process not unlike genetic evolution, it modifies and combines them into more complex ideas. As structures develop, the most useful and interesting ones-judged according to standards encoded in the program-survive.
At the time of the Traveller tournament, Lenat had already used a forerunner of Eurisko to grow mathematical concepts, getting the program to rediscover arithmetic and some theorems in elementary number theory. Now the structures Lenat wanted to see evolve were Traveller fleets. He provided the program with descriptions of 146 Traveller concepts, some of them as basic as Acceleration, Agility, Weapon, Damage, and even Game Playing and Game. Others were more specific: Beam Laser, Meson Gun, Meson Screen, and Computer Radiation Damage.
A Eurisko concept can be thought of as a box containing “slots” filled with information describing it. For example, the “Is A” slot in the box representing Energy Gun indicates that it is a Defensive Weapon Type and an Offensive Weapon Type—and a Physical Game Object, as well. These concepts are, in turn, described by other boxes. Another slot tells Eurisko that information on Energy Gun’s firing range will be found in a box called Energy Gun Attack Info.
Johnson01.jpg Douglas B. Lenat
With a network of these boxes interlinked in its memory, Eurisko began designing ships and simulating battles. After each altercation, it analyzed the results, made adjustments to the fleets and tried the battle again. In the process, Eurisko tested Traveller concepts by natural selection. For example, after a number of battles, Eurisko discovered how easy it was to provide ships with enough armor to protect them against energy guns. Thus the value in the Worth slot of Energy Gun, which was originally set at 500, was eventually lowered to 100. Weapons that proved more valuable would increase in worth, toward a maximum value of 1000.
Gradually an ever-more-invincible Traveller fleet evolved.
“At first,” Lenat later wrote, “mutations were random. Soon, patterns were perceived: more ships were better; more armor was better; smaller ships were better; etc. Gradually, as each fleet beat the previous one…its lessons were abstracted into new specific heuristics.”
When Eurisko began its experiments, the My Creator slot in each of its concepts all contained the name Lenat. But, as Eurisko played, an increasing number of the slots were filled with the name of the heuristic that had been used to synthesize them.
Eurisko was creating concepts on its own. It was distilling thousands of experiences into the judgmental, almost intuitional, knowledge that constitutes expertise—rules that can’t always be proved logically, that can’t guarantee a correct answer, but that are reliable guides to the way the world works, a means of cutting through complexity and chaos.
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