GENERATION
COMPUTERS
by Richard Grigonis
Richard Grigonis is a regular contributor of articles on artificial intelligence and future microcomputer designs for Dr. Dobb's Journal. He is currently employed by the Children's Television Workshop.
Even the most enthusiastic home computer owners have little idea of the link their machines represent in the historical chain of computer technology. It is a chain that runs from the ancient abacus and Charles Babbage's Analytical Engine of the nineteenth century, through the Apples and Commodores of the present, all the way to the awe-inspiring fifth-generation computers of the future.
Consider this: the "home computers" of the 1990s will surely have processing capabilities equivalent to those of the Cray-2, today's most powerful computer.
What kind of computing power are we talking about? As far as sheer processing speed is concerned, the present situation looks like this: A typical home computer, with microprocessor switches turning on and off at two to four million cycles per second and running a program written in a fast computer language like C or FORTH, can perform a few thousand arithmetic operations per second. The Cray-1, which costs about $10 million, performs between 160 and 200 million arithmetic operations per second. The Cray-2 handles over a billion arithmetic operations per second. To put it another way, a program that takes twelve minutes to run on an Apple will be executed on a Cray-1 in about three one-hundredths (0.03) of a second, and the same program will run on a Cray-2 in about six-thousandths (0.006) of a second.
Indeed, microcomputers have some catching up to do. But wait. The Apple Lisa and Macintosh, the Sage II and the Fortune 32:16 are microcomputers that all have a processor known as the Motorola 68000, which boosts the computational power of these $3,000 to $10,000 machines up to that of a superminicomputer costing hundreds of thousands of dollars. The next generation of microprocessors will be even faster.
Computer owners may well wonder what they're going to do with all this processing power. The answer: artificial intelligence. A sophisticated AI program would eliminate the need for users to write programs, since they could communicate their orders to the computer via ordinary English. Such a program, however, must do a large number of symbolic calculations on a huge amount of data or "real-world knowledge." AI is the ultimate programming challenge, both for the programmer in terms of design and for the computer in terms of execution time.
Structured Intelligence
This brings us to the Japanese Fifth Generation computer project. The Japanese have been working feverishly on a billion-dollar project, with a target date of 1989, to design and build a computer that is not only a hundred times faster than a Cray but contains AI software as well. This software would be capable of simulating experts in fields like medicine or geology, playing games like chess or Go at a grandmaster level, analyzing documents for factual errors as well as grammatical and spelling errors, and translating documents from one language into another. It all sounds great, but the Japanese are making a few blunders along the way. To understand how, we should take a look at programming languages in general and their relationship to AI.
Let's start by saying that computers are "universal Turing machines," which is a way of saying that computers are universal calculators. Any procedure (or algorithm, as it's called) that can be conceived of can be calculated or performed by a computer. If you believe that the human mind arises from the physical workings of the brain, then, since a computer can theoretically simulate anything in the physical world, you have automatically declared that a computer can simulate human thinking processes. The act of writing a program in the computer's own language (little 1s and 0s) is quite time-consuming, so high-level languages were developed that enable the programmer to instruct the machine by typing in commands like PRINT 2 + 2 instead of 10011101, 00000010, 01010011, 00000010 or whatever. Although there are many different programming languages designed with special attributes for special jobs (FORTRAN and APL for science/engineering, COBOL for business, BASIC for beginning programmers), any algorithm can be written in any language. The list processing language (LISP) developed by McCarthy in 1958 is considered by everyone to be the language for AI research, and yet, if the the need arose, we could look at a LISP program, figure out what the algorithm or procedure is, then rewrite the program in a different language such as BASIC or even COBOL. It would be a programmer's nightmare, of course, and the new program would be much larger in a more "inefficient" language, but it could be done.
Program Limits
We do not even need the full capabilities of a computer language to express any algorithm in a program. This idea had its origin in the Structure Theorem first presented in a classic mathematical paper by C. Bohm and G. Jacopini with the ominous title Flow Diagrams, Turing Machines, and Languages with Only Two Formation Rules. This paper introduced not a new computer language, but a style of programming called "structured programming" or, more technically, "programming by stepwise refinement," that could be used with any program.
To put it simply, Bohm and Jacopini discovered that all computer languages, large and small, come equipped with the following basic features:
1) Sequences of two or more operations (add A to B, then divide it by C, then print the result).
2) Decisions or choices (IF A THEN B ELSE C).
3) Repetitions of an operation until a certain condition is true. One of these is the Do-While loop (keep adding 1 to X While X is less than 10). The other is the Do-Until loop (keep adding 1 to X Until X equals 10).
The Structure Theorem mathematically proves that the expression of any algorithm in any language (i.e., any possible program, including one simulating human intelligence) can be written using only combinations of the three basic programming rules mentioned above!
At first glance, it looks as if tremendous restrictions are placed on the programmer, and yet by employing this "structured programming" method one actually shortens the time it takes to write, "debug" or modify any given program. This is because structured programming forces us to break a single complicated problem into several simple subproblems, then breaking these in turn into several more simple subsubproblems, until the programmer has reduced the original, highly complex problem into a large number of interlocking, very simple problems that are easily coded as a program. This technique is known as reductionism, decomposition or top-down design.
The Smart Set
What everyone seems to have forgotten is that artificial intelligence at the "grass roots" level is just another programming problem-like listing recipes or keeping track of one's stamp collection, only several orders of magnitude greater. Of course, no one in the AI field would dare suggest this in public. It all sounds too easy, as if writing the ultimate, ultra-intelligent program were more a matter of tenacity than of divinely inspired programming wizardry. And yet no strange languages or high priests of programming are necessary. The only special requirement is one of hardware, namely, a computer with immense storage capacity and a processor that can perform billions of calculations per second.
One final programming thought: the length of a program does not depend on the complexity of the algorithm to be executed; rather, it depends on the size of the computer language's vocabulary. Some languages (e.g., LISP and FORTH) have an advantage over others in that they are "extensible," enabling the programmer to add new words with corresponding new functions. A whole program could be as short as an ordinary English sentence if the language has been immensely extended (presumably with structured techniques) to include the English vocabulary, rules of grammar and semantics.
So, although any algorithm can be represented in any language, extensible languages are better to work with and produce much shorter, easier-to-read programs than do BASIC and COBOL, for example. The Japanese, however, have ignored LISP and chosen a rather strange language called PROLOG (PROgrammable LOGic) to run on their Fifth Generation computer. PROLOG forces the programmer to use pure logic, which means the computer must take the facts it knows about and calculate all their possible logical relationships, or inferences. If the computer knows a lot of facts, this process can lead to an unfortunate situation called a "combinatorial explosion" in which calculations take almost forever to complete. So, unless they radically change the language they are using, the Japanese may find that their much touted monster computer won't work at all. In fact, a number of AI problems are so tremendously complex (among them, playing a perfect game of chess) that it would take any computer many centuries to solve them.
Multi-Mentation
One answer to the problem of complex programming is to build the computer with more than one processor, then break up the program into pieces and assign each piece to a separate processor. With many processors working on a problem simultaneously, or "in parallel," the program in theory executes much faster.
In fact, fifty research projects in the United States are working on "parallel processing" or, as it is also called, "distributed array processing." These include:
• Tom McWilliams' 16-processor S-1 computer at the Lawrence Livermore National Laboratory, running at about two billion arithmetic operations per second.
• The Denelcor Company's mysterious HEP-2 computer, to be ready in 1986, capable of twelve billion operations per second.
• Salvatore Stolfo's 1,023-processor machine at Columbia University.
• David Elliot Shaw's computer, also at Columbia, being developed for the Defense Advanced Research Projects Agency (DARPA) and projected to have 256,000 processors by 1987, a million by 1990.
Another solution is that it might be possible one day to build a sixth-generation computer with a processor whose signals travel faster than the speed of light. This would improve the processing speed considerably, to say the least! Faster-than-light signals would seem an impossibility, but there are three ways we might achieve them: tachyons, the Einstein-Podolsky-Rosen (EPR) effect and the "advanced potentials" solution to the moving charge equations derived from Maxwell's electromagnetic theory. Whew! I'd love to try to explain it further, but I'd need another 8,600 words, the length of my original paper on the subject. Besides, it's not time yet to run over to ComputerLand and place your order: sixth-generation computers probably won't appear for decades.
In contrast to developing advanced hardware, creating the artificial intelligence software to go with it seems to be a wide-open field. Who will be the first to write the ultimate AI program? With the appearance of cheap supermicrocomputers over the next ten years, it could just as well be a fifteen-year-old in Montana as a thousand software engineers working together in Japan. Who knows? Perhaps you'll give it a try yourself ...
| A MICRO VISION The Hopewell family was first on their block to buy each new product. They had even brought home a robot-though Ed Hopewell got his money back when the Bulatron summoned the police every time he came home late from the office. Their latest acquisition was the Intelligent Processing Superluminal Integratron, billed as "the very last computer you'll ever want to own." The small black box now sat on the table next to an odd-looking helmet. Deciding not to wait for his wife to return from driving the kids to school, Ed flipped up the screenand donned the helmet. A small spot of laser light appeared. "Hey!" Ed exclaimed. "It actually works!" OF COURSE, intoned an androgynous voice. Ed stared at the machine. "Who said that?" I DID, answered IPSI. I AM DECODING YOUR BRAIN WAVES. A little nervous now, Ed glanced down at the box and noticed a small red button. He pushed it. AH, YOU HAVE ACTIVATED THE TEMPORAL RELEASE, IPSI recited. IN LIEU OF ORDINARY ELECTRICAL SIGNALS, MY SUPERLIMINAL PROCESSOR USES TACHYONS, OR PARTICLES THAT TRAVEL FASTER THAN THE SPEED OF LIGHT. WHATEVER TRAVELS FASTER THAN LIGHT ALSO TRAVELS BACK IN TIME. MY SP, THEREFORE, WILL ENABLE ME TO ANSWER QUESTIONS BEFORE YOU ASK THEM. "That's impossible," said Ed. "What if I want the answer to-" FOUR, the machine intoned. "-two plus two," Ed finished. "Well, if-" IF I AM SO INTELLIGENT, CAN I COMMENT ON THE COMMODITIES MARKET? CERTAINLY. YOUR INVESTMENT IN SOUTH AFRICAN OSTRICH FEATHERS WILL BRING MRS. HOPEWELL A TIDY PROFIT. "Mrs. Hope-" AS YOUR BENEFICIARY ... YOU SEE, MR. HOPEWELL, MY PROCESSOR HAS INFORMED ME OF YOUR IMMINENT DEMISE. Ed sat frozen in his chair. "My immi " THREE POINT EIGHT-OH MINUTES FROM NOW, YOU WILL PROCEED DOWN SYCAMORE AVENUE. YOU WILL DRIVE INTO THE PATH OF A LARGE TRUCK WITH FAULTY BRAKES. "But it doesn't have to be that way!" Ed cried. THE UNIVERSE MAY AT TIMES BE RATHER UNPREDICTABLE ON THE SUBATOMIC LEVEL, BUT IT IS QUITE FORESEEABLE ON THE LEVEL OF DIURNAL EXISTENCE. YOU WILL LEAVE SHORTLY. Tearing off the helmet, Ed got up and disconnected the machine. Why should he listen to the ravings of a pile of silicon? Still, it's never a good idea to tempt fate, he thought as he drifted out to the driveway to check for rain. He would not go into work today. No, he would spend the day tending to nice, safe chores. Settling himself behind the steering wheel, he began a mental list. "It's a good time to get those screens up," he said aloud. "Maybe paint the porch," he added as he turned the key in the ignition. RICHARD GRIGONIS |
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