Japan's Fifth Generation Computer Systems: Success or Failure?

(1982-1984) Initial Stage

During the initial stage, research was conducted on the basic technologies for FGCS. The technologies developed included:

1. ESP (extended self-contained Prolog), a sequential logic-programming language based on Prolog.

2. PSI (personal sequential inference machine), the world's first sequential inference computer to incorporate a hardware inference engine.

3. SIMPOS (sequential inference machine programming and operating system), the world's first logic-programming-language-based operating system written with ESP for the PSI.

4. GHC (guarded horn clauses), a new parallel-logic language for the implementation of parallel inference.

(1985-1988) Intermediate Stage

During the intermediate stage, research was done on the algorithms needed for implementation of the subsystems that would form the basis of FGCS and on the basic architecture of the new computer.

Furthermore, on the basis of this research, small and medium-sized subsystems were developed. The technologies developed included:

1. KL1, a logic language for parallel inference.

2. PIMOS (parallel inference machine operating system), a parallel-machine operating system based on the use of KL1 (kernel horn clauses 1).

3. KAPPA (knowledge application oriented advanced database and knowledge base management system), a knowledge-base management system capable of handling large amounts of complex knowledge.

4. MultiPSI, an experimental parallel inference machine consisting of 64 element processors linked together in the form of a two-dimensional lattice.

(1989-1992) Final Stage

During the final stage, the object was to put together a prototype fifth generation computer based on the technologies developed during the two preceding stages. The project team developed a number of additional features including:

1. PIM (parallel inference machine), a parallel inference computer consisting of 1000 linked element processors.

2. Improvement of PIMOS.

3. KAPPA-p, a parallel data-management system. For the knowledge programming system the team also developed.

4. Interactive interface technology.

5. Problem-solving programming technology.

6. Knowledge-base creation technology.

7. To test the prototype system, the team also carried out research into the integration and application of parallel programming technology.

8. several application software programs were developed to run on the PIM.

(1993-1994) Wrap Up

The project continued on a more limited scale during 1993 and 1994.

In addition to follow-up research on, say, a new KL1 programming environment (called KL1C) on sequential and parallel UNIX-based machines, many efforts were made to disseminate FGCS technologies, for instance, to distribute free ICOT software and to disclose technical data on the Internet.

Overreaction

Some people overreacted and spoke even of a technological war. Today some people again overreact. As they see that their fears have not materialized, they regard the project as a failure.

Evaluation

Scientific:

• ✅ Hardware: use of parallelism

• ✅ Software: use of logic programming

• ✅ Applications

  • ❌ No natural language, no pattern recognition

• ❌ Break-through in architecture

• ❌ Break-through in software

Economic:

• ✅ Impact on Japanese researchers

• ❌ Impact on Japanese hardware makers

Social:

• ✅ International scientific reputation

  • ❌ But no solution to social problems in Japan

Positive

• ICOT has shown the ability of Japan to innovate in computer architectures.

• The ICOT architectures' peak parallel performance is within the range of the original performance goals.

• The PIMs represent an opportunity to study tradeoffs in parallel symbolic computing which does not exist elsewhere.

• KL1 is an interesting model for parallel symbolic computation, but one which is unlikely to capture the imagination of US researchers.

• PIMOS has interesting ideas on control of distribution and communication which US researchers should evaluate seriously.

• ICOT has been one of the few research centers pursuing parallel symbolic computations.

• ICOT has been the only center with a sustained effort in this area.

• ICOT has shown significant (i.e. nearly linear) acceleration of non regular computations (i.e. those not suitable for data parallelism of vectorized pipelining).

• ICOT created a positive aura for AI, Knowledge Based Systems, and innovative computer architectures. Some of the best young researchers have entered these fields because of the existence of ICOT.

Negative

• ICOT has done little to advance the state of knowledge based systems, or Artificial Intelligence per se.

• ICOT's goals in the area of natural language were either dropped or spun out to EDR.

• Other areas of advanced man machine interfacing were dropped.

• Research on Very Large Knowledge bases were substantially dropped.

• ICOT's efforts have had little to do with commercial application of AI technology. Choice of language was critical.

• ICOT's architectures have been commercial failures. Required both a switch in programming model and the purchase of cost ineffective hardware.

• ICOT hardware has lagged behind US hardware innovation (e.g. the MIT Lisp Machine and its descendants and the MIT Connection Machine and its descendants).

• Application systems of the scale described in the original goals have not been developed (yet).

• Very little work on knowledge acquisition.

The early documents discuss the management of very large knowledge bases, of large scale natural language understanding and image understanding with a strong emphasis on knowledge acquisition and learning. Each of these directions seems to have been either dropped, relegated to secondary status, absorbed into the work on parallelism or transferred to other research initiatives.

The ICOT work has tended to be a world closed in upon itself. In both the sequential and parallel phases of their research, there has been a new language developed which is only available on the ICOT hardware. Furthermore, the ICOT hardware has been experimental and not cost effective. This has prevented the ICOT technology from having any impact on or enrichment from the practical work.

Changes

It is remarkable how little attention is given to the notion of parallel processing, while this notion turned out to be of such great importance for the whole project.

First, in my opinion the original goal of the FGCS project changed its emphasis from what has been described above as primarily a knowledge information processing system, KIPS, with very strong capabilities in man-machine interaction, such as natural language processing, into the following:

A computer system which is:

• Easy to use intellectually

• Fast in solving complex problems

In combining the two ideals:

• Efficient for the mind

• Efficient for the machine

The intellectual process of translating a problem into the solution of that problem should be simple. By exploiting sophisticated (parallel processing) techniques the computer should be fast.

Research Impact

Japan has indeed proved that it has the vision to take a lead for the rest of the world.

They acted wisely and offered the results to the international public for free use, thus acting as a leader to the benefit of mankind and not only for its own self-interest.

One of the major results and successes of the FGCS project is its effect on the infrastructure of Japanese research and development in information technology.

The technical achievements of ICOT are impressive. Given the novelty of the approaches, the lack of background, the difficulties to be solved, the amount of work done which has delivered something of interest is purely amazing; this is true in hardware as well as in software.

The fulfillment of the vision, should I say working on the "grand plan" and bringing benefits to the society, is definitely not at the level that some people anticipated when the project was launched. This is not, to me, a surprise at all, i.e. I have never believed that very significant parts of this grand plan could be successfully tackled.

Overall, the project has had a major scientific impact, in furthering knowledge throughout the world of how to build advanced computing systems.

I agree that the international impact of the project was not as large as one hoped for in the beginning. I think all of us who believed in the direction taken by the project, i.e. developing integrated parallel computer systems based on logic programming, hoped that by the end of the 10 years' period the superiority of the logic programming approach will be demonstrated beyond doubt, and that commercial applications of this technology will be well on their way. Unfortunately, this has not been the case. Although ICOT has reached its technological goals, the applications it has developed were sufficient to demonstrate the practicality of the approach, but not its conclusive superiority.

Lessons Learned

1. Be aware that government-supported industrial consortia may not be able to 'read the market', particularly over the long term.

2. Do not confuse basic research and advanced development.

3. Expect negative results but hope for positive. Mid-course corrections are a good thing.

4. Have vision. The vision is critical: people need a big dream to make it worthwhile to get up in the morning.

Logic Programming

It certainly provided a tremendous boost to research in logic programming.

I was expecting however to see 'actual use' of some of the technology at the end of the project. There are three ways in which this could have happened.

The first way would have been to have real world applications, in user terms; only little of that can be seen at this stage, even though the efforts to develop demonstrations are not be underestimated.

The second would have been to the benefit of computer systems themselves. This does not appear to be directly happening, at least not now and this is disappointing if only because the Japanese manufacturers have been involved in the FGCS project, at least as providers of human resources and as subcontractors.

The third way would have been to impact computer science outside of the direct field in which this research takes place: for example to impact AI, to impact software engineering, etc.; not a lot can yet be seen, but there are promising signs.

I am genuinely impressed by the scientific achievements of this remarkable project. For the first time in our field, there is a uniform approach to both hardware and software design through a single language, viz. KL1.

It is nearly unbelievable how much software was produced in about two and a half years written directly or indirectly in KL1.

There are at least three aspects to what has been achieved in KLI:

First the language itself is an interesting parallel programming language. KL1 bridges the abstraction gap between parallel hardware and knowledge based application programs. Also it is a language designed to support symbolic (as opposed to strictly numeric) parallel processing. It is an extended logic programming language which includes features needed for realistic programming (such as arrays).

However, it should also be pointed out that like many other logic programming languages, KL1 will seem awkward to some and impoverished to others.

Second is the development of a body of optimization technology for such languages. Efficient implementation of a language such as KL1 required a whole new body of compiler optimization technology.

The third achievement is noticing where hardware can play a significant role in supporting the language implementation.

By Companies

The main Companies involved in the project were Fujitsu, Hitachi, Mitsubishi Electric, NEC, Oki, Toshiba, Matsushita Electric Industrial and Sharp.

Almost all companies we interviewed said that ICOT's work had little direct relevance to them.

The reasons most frequently cited were: The high cost of the ICOT hardware, the choice of Prolog as a language and the concentration on parallelism.

However, nearly as often our hosts cited the indirect effect of ICOT: the establishment of a national project with a focus on 'fifth generation technology' had attracted a great deal of attention for Artificial Intelligence and knowledge based technology.

Several sites commented on the fact that this had attracted better people into the field and lent an aura of respectability to what had been previously regarded as esoteric.

Hardware

During the first 3 year phase of the project, the Personal Sequential Inference machine (PSI 1) was built and a reasonably rich programming environment was developed for it.

Like the MIT machine, PSI was a microprogrammed processor designed to support a symbolic processing language. The symbolic processing language played the role of a broad spectrum 'Kernel language' for the machine, spanning the range from low level operating system details up to application software. The hardware and its microcode were designed to execute the kernel language with high efficiency. The machine was a reasonably high performance work station with good graphics, networking and a sophisticated programming environment. What made PSI different was the choice of language family. Unlike more conventional machines which are oriented toward numeric processing or the MIT machine which was oriented towards LISP the language chosen for PSI was Prolog.

The choice of a logic programming framework for the kernel language was a radical one since there had been essentially no experience anywhere with using logic programming as a framework for the implementation of core system functions.

Several hundred PSI machines were built and installed at ICOT and collaborating facilities; and the machine was also sold commercially. However, even compared to specialized Lisp hardware in the US, the PSI machines were impractically expensive. The PSI (and other ICOT) machines had many features whose purpose was to support experimentation and whose cost/benefit tradeoff had not been evaluated as part of the design; the machines were inherently non-commercial.

The second 3 year phase saw the development of the PSI 2 machine which provided a significant speedup over PSI 1. Towards the end of Phase 2 a parallel machine (the Multi-PSI) was constructed to allow experimentation with the FGHC paradigm. This consisted of an 8 × 8 mesh of PSI 2 processors, running the ICOT Flat Guarded Horn Clause language KL1.

The abstract model of all PIMs consists of a loosely coupled network connecting clusters of tightly coupled processors. Each cluster is, in effect, a shared memory multiprocessor; the processors in the cluster share a memory bus and implement a cache coherency protocol. Three of the PIMs are massively parallel machines.

Multi-Psi is a medium scale machine built by connecting 64 Psi's in a mesh architecture.

Even granting that special architectural features of the PIM processor chips may lead to a significant speedup (say a factor of 3 to be very generous), these chips are disappointing compared to the commercial state of the art.

Specialized Hardware

Another most important issue, of a completely different nature, is the question of whether ICOT was wise to concentrate so much effort on building specialised hardware for logic programming, as opposed to building, or using off the shelf, more general purpose hardware not targeted at any particular language or programming paradigm. The problems with designing specialised experimental hardware is that any performance advantage that can be gained is likely to be rapidly overtaken by the ever-continuing rapid advance of commercially available machines, both sequential and parallel. ICOT's PSI machines are now equalled if not bettered for Prolog and CCL performance by advanced RISC processors.

Many are skeptical about the need for special purpose processors and language dedicated machines. The LISP machines failed because LISP was as fast, or nearly as fast, implemented via a good compiler on a general purpose machine. The PSI machines surely do not have a market because the latest Prolog compilers, compiling down to RISC instructions and using abstract interpretation to help optimize the code, deliver comparable performance.

It is interesting to compare the PIMs to Thinking Machines Inc.'s CM-5; this is a massively parallel machine which is a descendant of the MIT Connection Machine project. The CM-5 is the third commercial machine in this line of development.

Although the Connection Machine project and ICOT started at about the same time, the CM-5 is commercially available and has found a market within which it is cost effective.

Demo Applications

I think that this was the result of the applications being developed in an artificial set-up. I believe applications should be developed by people who need them, and in the context where they are needed.

In general, I believe that too little emphasis was placed on building the best versions of applications on the machines (as opposed to demonstration versions).

In a nutshell, the following has been achieved: for a number of complicated applications in quite diverse areas, ranging from Molecular Biology to Law it has been shown that it is indeed possible to exploit the techniques of (adapted) logic programming, LP, to formulate the problems and to use the FGCS machines to solve them in a scalable way; that is parallelism could indeed profitably be used.

The demonstrations involved:

1. A Diagnostic and control expert system based on a plant model

2. Experimental adaptive model-based diagnostic system

3. Case-based circuit design support system

4. Co-HLEX: Experimental parallel hierarchical recursive layout system

5. Parallel cell placement experimental system

6. High level synthesis system

7. Co-LODEX: A cooperative logic design expert system

8. Parallel LSI router

9. Parallel logic simulator

10. Protein sequence analysis program

11. Model generation theorem prover: MGTP

12. Parallel database management system: Kappa-P

13. Knowledge representation language: QUIXOTE

14. A parallel legal reasoning system: HELIC-II

15. Experimental motif extraction system

16. MENDELS ZONE: A concurrent program development system

17. Parallel constraint logic programming system: GDCC

18. Experimental system for argument text generation: Dulcinea

19. A parallel cooperative natural language processing system: Laputa

20. An experimental discourse structure analyzers

They have some real success on a technical level, but haven't produced applications that will make a difference (on the world market).

Programming Languages

Two extended Prolog-like languages (ESP and KL0) were developed for PSI-1. ESP (Extended Self Contained Prolog) included a variety of features such as coroutining constructs, non-local cuts, etc. necessary to support system programming tasks as well as more advanced Logic Programming. SIMPOS, the operating system for the PSI machines, was written in ESP.

Phase 3 has been centered around the refinement of the KL1 model and the development of massively parallel hardware systems to execute it.

KL1 had been refined into a three level language:

• KLI-b is the machine level language underlying the other layers

• KLI-c is the core language used to write most software; it extends the basic FGHC paradigm with a variety of useful features such as a macro language

• KLI-p includes the 'pragmas' for controlling the implementation of the parallelism

Much of the current software is written in higher level languages embedded in KL1, particularly languages which establish an object orientation. Two such languages have been designed: A'UM and AYA. Objects are modeled as processes communicating with one another through message streams.

Two languages of this type developed at ICOT are CAL (Constraint Avec Logique) which is a sequential constraint logic programming language which includes algebraic, Boolean, set and linear constraint solvers.

A second language, GDCC (Guarded Definite Clauses with Constraints) is a parallel constraint logic programming language with algebraic, Boolean, linear and integer parallel constraint solvers.

OS

Multi-PSI supported the development of the ICOT parallel operating system (PIMOS) and some initial small scale parallel application development. PIMOS is a parallel operating system written in KL1; it provides parallel garbage collection algorithms, algorithms to control task distribution and communication, a parallel file system, etc.

AI

Interest in AI (artificial intelligence) boomed around the time and companies started to realize the potential value of FGCS research as a complement to their own AI research.

Databases

In the area of databases, ICOT has developed a parallel database system called Kappa-P. This is a 'nested relational' database system based on an earlier ICOT system called Kappa. Kappa-P is a parallel version of Kappa, re-implemented in KL1.

It also adopts a distributed database framework to take advantage of the ability of the PIM machines to attach disk drives to many of the processing elements. Quixote is a Knowledge Representation language built on top of Kappa-P.

It is a constraint logic programming language with object-orientation features such as object identity, complex objects described by the decomposition into attributes and values, encapsulation, type hierarchy and methods. ICOT also describes Quixote as a Deductive Object Oriented Database (DOOD).

Theorem Proving

Another area explored is that of Automatic Theorem Proving. ICOT has developed a parallel theorem prover called MGTP (Model Generation Theorem Prover).