Programmer 7500

home *** CD-ROM | disk | FTP | other *** search

/ Programmer 7500 / MAX_PROGRAMMERS.iso / CLIPPER / MISC / AIDEMO.ZIP / MANUAL.ESI < prev next >

Wrap

Text File | 1986-12-06 | 51.6 KB | 1,376 lines

ESIE The Expert System Inference Engine Knowledge Engineer's Manual Lightwave August 1985 P.O. Box 16858 Tampa, FL 33617 Copyright 1985, All Rights Reserved. The ESIE distribution diskette, of which this manual is one file, may be freely copied and distributed. Printed copies of this manual, or this manual without the rest of the files on the distribution diskette, may not be copied or reproduced in any form. Page 2 Table of Contents Introduction . . . . . . . . . . . . . . . . . . . . . . 3 What is Shareware? . . . . . . . . . . . . . . . . . . . 4 What is ESIE? . . . . . . . . . . . . . . . . . . . . . . 5 Why ESIE? . . . . . . . . . . . . . . . . . . . . . . . . 6 ESIE Requirements . . . . . . . . . . . . . . . . . . . . 9 The ESIE Distribution Diskette . . . . . . . . . . . . . 11 Starting ESIE . . . . . . . . . . . . . . . . . . . . . . 12 The ESIE Top Level . . . . . . . . . . . . . . . . . . . 13 The ESIE Rule Structure . . . . . . . . . . . . . . . . . 14 Some Example Knowledge Bases . . . . . . . . . . . . . . 18 Building Your Own Knowledge Base . . . . . . . . . . . . 20 What Happens During a Consultation . . . . . . . . . . . 22 Paying For and Obtaining the Next Version of ESIE . . . . 23 Planned Enhancements to ESIE . . . . . . . . . . . . . . 24 Bibliography . . . . . . . . . . . . . . . . . . . . . . 25 Page 3 Introduction ESIE (pronounced "easy") is the acronym for Expert System Inference Engine. ESIE is an "expert system shell." With ESIE you can put some "smarts" into your personal computer. You can build custom "knowledge bases" (KBs) that can be used to aid people, like you and me, in doing things that we would not be capable of doing, or doing as well, without the system. ESIE knowledge bases can be built to help us make decisions or make our computers "more human." This manual is designed for the person who already has some experience in the field of Artificial Intelligence (AI). If this applies to you - then hi! - we probably met somewhere. If not we urge you to print and read the files TUTOR and HISTORY which will give you: a small history and working knowledge of AI, help you learn about ESIE, give you enough information to build your own knowledge bases, and provide some tips for building better knowledge bases in the future. If you only intend on using ESIE with a knowledge base written for you, then you need only print and read the file USER. For those for whom this manual was intended we expect that you will have done some work, or at least some reading, in knowledge based applications. We can only assume that you know something about rule structures, knowledge representation, and inferencing. If you need to bone up on this information, might we suggest that you scan over the file TUTOR? In any case, welcome to ESIE! Page 4 What Is Shareware? Shareware is a software distribution concept. In shareware, it is believed: that people will pay for something they find useful, that most software costs too much, that copy protection schemes can sometimes be frustrating even to the most honest user, and that software users want to support software authors while not necessarily supporting the software middle men. Shareware is a marketing concept. The term was probably originally coined by Bob Wallace of Quicksoft, Inc. Mr. Wallace wrote PC-Write (c), a shareware full-feature text editor. We personally like PC-Write and prefer it as our editor-of-choice. We believe you will find PC-Write useful and to that end we will send you a copy of it if you "pay" for ESIE at $145. ESIE is distributed under the Shareware concept. You receive the software first, from whatever source that may be, and pay only what you think the software is worth. You are free, and encouraged, to share copies of the distribution diskette with others. ESIE is marketed under the shareware concept. We prefer to think of ESIE as living software: software that continues to develop and get better, more powerful. We believe ESIE is a useful tool as it is, but can be improved. However, support for living software must come from somebody. Even software authors and AI researchers cannot live on discovery and love alone. In shareware this support comes from you - the user. If you feel that ESIE is useful to you, send what your conscience dictates. ESIE is paid for on the honor system. However, if you send at least $75 you will receive the most recent version of ESIE, free. If you send at least $145 you will receive: the most recent version of ESIE, fully commented source code for ESIE (ESIE was written in Pascal), our sincere thanks for your support, a copy of PC-Write (c) - a shareware full-feature text editor fully compatible with ESIE, and access to the ESIE technical support line, all free. Your comments towards ESIE are solicited even if you do not desire support. For this, please print and fill out the file FORM and send it in. Mail and money for ESIE can be sent to: Lightwave; P.O. Box 16858; Tampa, FL 33617. P.O. Box 290539 is also a Lightwave address. Page 5 What Is ESIE? ESIE is the acronym for Expert System Inference Engine, and that is exactly what it is. ESIE loads in a knowledge base, and builds inferences out of the rules contained therein, to act like an Advisor. It is an Artificial Intelligence expert system shell. An infinite multitude of knowledge bases can be used by ESIE. The normal gamut of expert systems (ES) can be built for and used by ESIE. Tools such as system configurators, medical experts, oil and gas exploration, etc, can all be done in ESIE. ESIE is a rule-based backward chaining inference engine. The acronym was also selected because ESIE is easy to use. If you are like we are, then you have pulled out more than a few hairs trying to work with the complexity of most ES shells (ESS) available today. We can vividly remember thinking, "They've got to be kidding" with six different ESSs. Further, we are sure that if we uncovered one more "undiscovered" bug in an ESS that we would be a permanent residents at Bellevue. ESIE is not like that. It is easy to use and easy to learn. It is a fairly simple system so that we feel good about the testing and debugging that went into ESIE. Since ESIE was written in Pascal, and not a pirated version of something hard to debug, like Prolog, it should hold you in good stead. If you were, or are, currently working for a corporation or university then you are also aware of the difficulty in getting management approval for a very expensive piece of equipment. ESIE is built to put some competitiveness into the ESS market. ESIE is very inexpensive and rivals many ESSs in power and it beats nearly all in speed. The shareware distribution concept fits that definition well. Knowledge based inference engines have a rather small market at present, but that soon may change. The advent of low cost and readily available software might help the spread and acceptance of AI. Page 6 Why ESIE? Why did we build ESIE? Well, there are lots of reasons, and one of the most important is cost. Since you are a qualified AI person you are well aware of how much systems can cost. The best LISP processor in existence today will cost you more than $100,000.00 per person. Software and development time to build any expert system can jack the price up substantially. Now say you have targeted an area that looks pretty applicable to be "AIed." You know that when the system is complete you will want to install it in, say, fifty locations. You take six months to develop the first working model and spend $450,000.00 doing it. After you install your fifty stations you realize you have just spent $6,700,000.00. Your Vice President, in charge of new technology, unhooks his Thomson Automatic from the showcase wall and commits a most unnatural form of suicide. You would have to be working in some very high stakes game in order to recoup 6.7 million dollars through an expert system. Do you think the fifty installation points was to small? The numbers only get worse if you add more stations. The real cost to you comes in the form of specialized processors and software to run them. Many AI departments that we know of realize the problems inherent in a high stakes game of specialized processors, especially when the field is a new one to the company and the department. Therefore, many groups are turning towards existing hardware to meet their processing needs. Wisely, many are choosing micro computers because cost of installation is drastically reduced, and in many cases micros already exist at the target. This makes the cost of installation equal to development cost plus software cost. Great. So lets look at personal computer software cost. Believe it or not, there is quite a bit of AI software out there for personal computers. We have some kind of problem with most of it. Cost is still the biggest factor. Let us pick a popular price for an ESS in the marketplace: $12,000.00. Now your installation cost is way down, and because the package is a little more personal and available to your researchers, you are able to complete initial development in five months and spend $350,000.00. Now you install the system in your fifty locations, and you are lucky: every one of them has a personal computer available. You step back to admire your handiwork and realize you have just spent $950,000.00. The head of your department leaves work early and takes a long swim in the cooling tower of Unit 2 at Three Mile Island. Page 7 Obviously, cost is one of the great advantages of ESIE - its free. So lets say you decide to use ESIE on your target project, and that you take five months and $300,000 to build Release One. Let us also assume that, for whatever reason, you decide to pay for support for all fifty+ copies of ESIE that you need. (That would certainly make our day!) After your fifty station installation you realize you have only spent $307,250. The president of your corporation hands you the highest company award, and you get your picture on the cover of your company magazine - you are a hero. In addition to cost, availability is also key to your success as an AI department. You may freely make as many copies of the distribution diskette of ESIE as you like. Try that with another ESS, and, if you get past the copy protection, do it while staying out of jail. ESIE is instantly available to everyone in your group as well as everyone in your company. We personally have waited four months for a diskette to arrive - AFTER the check had been mailed from our accounting department. You can use ESIE now and forever with ease. Some of the other available packages that look really good to you may be difficult or impossible to obtain. Many colleges and universities will be more than happy to discuss their latest and greatest at conventions but ask for a copy? Forget it. Also, some systems will only run on certain machines - machines you may not have and certainly do not want to buy. ESIE will run on any MS/PC DOS computer with color or monochrome monitor and only 128 KB of RAM. ESIE is also easy to use and to learn. Of the knowledge bases distributed with ESIE, both DOCTOR and ANIMAL took less than eight hours apiece to build. We admit a little bias here, after all, we did build ESIE. So, it may take you ten hours, but you probably are better than we are, so it may only take you six. Another super advantage of ESIE is that you can obtain the source code. If you want to see the insides of an inference engine this is one of the best ways to do it. Most other system vendors get very edgy if you ask them how their system works. Also, if you decide that there is a feature that you simply MUST have in an ESS then you can change ESIE to fit your needs. However, if you print and fill out the file called FORM, with your requests for additional features, we might be persuaded to add them for you. We certainly want to keep improving ESIE. Last, but not least, is speed. This is one of our pet peeves concerning many ESSs today - they are just too slow. Many departments have switched to more powerful micros, such as the IBM PC AT (r), to offset slow software. Well, ESIE will run on those, too, but it does not have to. ESIE is fast, - very fast - compared to most ESSs in existence today. Spend Page 8 some time to do a benchmark of ESIE against any other system. We think you will be pleasantly surprised. All of the above are benefits to be gained from using ESIE: you drastically cut your costs (a hero maker in many a department), better availability to your software, easy to learn and use - cutting training time and costs and increasing productivity, obtainable source code, and much improved speed. Page 9 ESIE Requirements In order to use ESIE you do not need much at all. For hardware you will need: an MS-DOS (r) or IBM (r) computer with at least 128 KB of RAM, and a monitor. ESIE should run on any MS-DOS (r) computer, (it has been tested on several), but we just cannot guarantee that it will run on your particular machine. ESIE will run on the IBM PC jr, PC, XT, and AT (r). ESIE uses colors to make the whole system more user friendly. Therefore, a color monitor is recommended, but not required. We prefer to work with colors, especially in something that may be hard to follow - like AI. With a color monitor, ESIE: works with a blue background, has a top level with white text, asks questions in light cyan, gathers responses in light magenta, reports invalid responses in light red, performs trace functions in yellow, reports a completed session in yellow, and reports KB errors in light red. For software you only need DOS version 2.0 or higher, (including 3.0 and 3.1), and a word processor. Any word processor will do, but the word processor needs to be capable of producing flat or ASCII, files. You probably already have all the software you need. If you are not sure if your word processor produces flat ASCII files there are two tests: 1) try to build a short program with your word processor and run it through any compiler - if the compiler gets an upset stomach there is a good chance you need a different word processor, 2) take any text file you created with your editor, and at the DOS command level enter TYPE <fn>, where <fn> is the file you edited. If your file looks like a video game then you need a different editor. If it TYPEd your file as you had entered it then you are probably OK. If your editor does not produce flat files then do not panic. If you pay for a copy of ESIE at the $145 price we will send you one. The editor is called PC-Write (c) and it is a full-screen full-feature text editor. Of all the editors we have we prefer PC-Write. It just seems to "feel" the best for us. PC-Write is also a shareware product. We did not create PC-Write - it is a product of Quicksoft, Incorporated, and was written in whole or in part by Bob Wallace. If you can not stand waiting then you might check with your local PC User's Group - there is a good possibility they have PC-Write. Many word processors produce flat files as a matter of course. Nearly any text editor that is designed to be used by programmers, and therefore produce compilable source code, Page 10 generally produce flat files. Those word processors that are designed to be used primarily by office personnel, for the creation of correspondence, sometimes do not. They use a compression scheme, and often a coding scheme to control paging, in order to save disk and RAM space. We think it is a silly idea, but they never did listen to us. If you are hell bent on using your current text editor, and it is one of those that do not produce flat files, then you still may be in luck. In many of these editors you have an option of producing a flat file from your edited file through a process usually labeled exportation. By selecting that option through a menu you can produce a flat file that compilers, and ESIE, can read. One word of caution: make a copy of your file FIRST before attempting exportation. It seems that many companies did not bother to do much testing of this function and we have trashed many a file trying to export. Importing the file, or getting it back into editor format, is usually much worse. We would not even attempt it if we were you, but good luck if you do. In whatever editor you choose, the margins and spacing can be set to whatever you choose. ESIE reads from the file in free format. That means that your file can look pretty strange if you want it to. As long as the syntax is in the correct order the file will load properly. If it does not then ESIE will report an error in the knowledge base and return you to DOS. Page 11 The ESIE Distribution Diskette The first thing you should do is make a backup copy of the ESIE distribution diskette. This will protect you in case your working diskette gets damaged and will make it easier for you to pass along ESIE to your friends and associates. You can make a backup copy of ESIE using the DOS COPY or DISKCOPY command. You are free, and encouraged, to distribute copies of the distribution diskette to friends and associates. The definition of the distribution diskette is one that contains the following ten files in their original condition. You may not distribute any file without the others. Everything you need except hardware, DOS and an editor, is on the ESIE distribution diskette. These are the ten files found there: ESIE.COM - the ESIE system. MANUAL - this manual. READ.ME - a quick start guide. FORM - form to use for correspondence on ESIE. ANIMAL - an animal KB. GLASS - a glass KB. DOCTOR - a doctor KB. TUTOR - AI tutor. USER - manual for the end users. HISTORY - short history of AI. Page 12 Starting ESIE Getting ESIE fired up will probably be one of the easiest things you do today. The only two files you need in the computer to use ESIE are the ESIE.COM file and the file where the KB is. Of course, you may have as many files out there as you wish. For purposes of example, it will be assumed that you are using the ANIMAL example KB provided with the distribution diskette. When you start to build your own KBs, simply substitute that file for ANIMAL. ESIE will run in any drive and directory, including hard disks, as long as the ESIE.COM and KB files are present. When you have at least the above two files where you want them, simply type in ESIE at the DOS prompt. The ESIE introductory screen will appear. It contains information about the Shareware concept and some benefits you will receive if you pay for your copy of ESIE. At the top of the introductory screen is a prompt asking you to supply the file name where the knowledge base may be found. You may enter any name you please. If the file exists, then ESIE will attempt to load that file. If no loading errors are found, then ESIE will take you to the top level. If there are errors in loading the KB, then ESIE will list where it found the errors and return you to DOS. If the file does not exist, then you have the option of trying again. Just hitting the 'Y' or the 'N' key will answer this prompt. ESIE loads files faster than most, if not all, other ESSs, but be patient if you are loading a very large KB, especially from floppy diskette. Page 13 The ESIE Top Level You will know when you have reached the top level by the distinctive ESIE prompt. It looks like this: "==>". At the top level you have four different command options: TRACE ON, TRACE OFF, GO, and EXIT. While you can have as many leading and trailing blanks as you wish, ESIE is not quite free form on the command line; you must have one and only one space between the TRACE and YES/NO options. Other than that, ESIE is free form. Importantly, ESIE is case insensitive. Caps look just the same as smalls to ESIE. This is also true in the KB and in end user responses. ESIE is case insensitive everywhere. We like this feature. We hate building rules to take care of the same idea but duplicated everywhere to take care of case, and the idea that a variable means something different because the first letter is capitalized drives us up the wall. When you first enter the top level, trace is off by default. You can turn trace on using the TRACE ON command. Use trace when you are building your own KB and want to follow execution in order to debug the KB. Turning trace on will tell the system to constantly keep you informed of what it is currently looking for and what information it has learned. You can turn the trace back off again by entering the TRACE OFF command. The GO command is the command to tell ESIE to begin a consultation with the KB that was loaded. ESIE will continue with this consultation until it is complete or until an error is found in the logic of the KB. You may not turn trace on or off once a consultation has begun. If the user types in TRACE ON, TRACE OFF, GO or EXIT in response to a question, then ESIE will treat that as the response to the question. Once ESIE has completed the consultation, or found an error in the logic of the KB, it will return you to the top level for additional commands. Use the EXIT command in order to leave ESIE and return to DOS. After a consultation is complete, you have the option of entering ANY of the four commands, including GO, again. Page 14 The ESIE Rule Structure There are five types of rules in ESIE. That is all. Two of the rule types must be included once and only once, one may be included once or not at all, and the other two may be included from zero up to the maximum number of times, which, you will find, is quite large for a system like this. If you are familiar with IBM (r) manuals, then you will probably be able to read the following; then again, those never were our favorite manuals. Below is the syntax for the five types of rules in ESIE: [legalanswers is/are <variable> [<variable>]... *] goal is <variable> [if <variable> is/are <value> [and <variable> is/are <value>]... then <variable> is/are <value>]... [question <variable> is/are "<text>"]... answer is/are "<text>" <variable> First, let us list some specifics, then we will go into what each rule does. First and foremost: BLANKS are the only recognized delimiter in ESIE. There must be at least one blank between any two tokens in the KB. End-of-line and end-of-file are treated like blanks. This may seem a little cumbersome at first, especially to those of you who are used to special characters, such as quotation marks, also being considered as delimiters. ESIE is built this way primarily for speed. If blanks are the only recognized delimiter, then file loading can occur at a much greater clip. Anyway, we believe you will soon get used to tapping the space bar if you are not currently doing so. In the syntax above the '/' means "either or" you must choose between 'is' and 'are' for that one spot. This capability was added basically to enhance the readability of your new knowledge bases. The definition of <variable> and <value> might be a little different to what you are used to. In ESIE a <variable> or <value> can be ANY string of non-blank characters, including special and extended ASCII characters, up to 40 characters Page 15 long. Blanks may not appear in a <variable> or <value>. ESIE will treat small and capital letters identically. Therefore, all the following are valid <variables> and <values>: 1234567890()*&^%$#@!+_=[]{} .......................... wow!.i.can.type.in.anything WOW!.I.can.TYPE.in.ANYTHING The last two of the above are identical as far as ESIE is concerned. Although special characters are valid in <variables> and <values>, and may even lead such items, it would be a good idea to stay away from the mathematical symbols. Although ESIE does not currently do math, (it currently is designed for ideas, symbols, and other uses), that capability will probably be added in the future. Therefore, if your KB is loaded full of math symbols, it may not be compatible from one version of ESIE to the next. In this regard, especially look out for the minus sign - it habitually gets used in multi-word <variables>. A better alternative would be to use the period. The symbol "..." in the rule definition above means "repeat as often as desired", and that is exactly what you may do, as long as you are not exceeding some maximum. The brackets mean that the item is optional. You will note that LEGALANSWERS, IF, and QUESTION type rules may not even be included in the KB, although a KB without rules is not going to be of much use. The GOAL and ANSWER rule types must be included, and must be in the KB only once. If the LEGALANSWERS rule type is included, it can only be included once. Although the above way of listing rules is the order we prefer in a KB, there is absolutely no requirement that rules be placed in the KB in any order. In a fully-structured KB, in fact, the order of the rules is totally inconsequential, any rule or any rule type may come before or after any other rule or rule type. In some KBs the structure is not complete, so it may be wise to place some rules before others. We will make this more clear in the Building Your Own Knowledge Base section. The <text> parts of the above rule types may be any of the 256 characters of the extended ASCII character set except for the quotation mark. The quotation mark terminates <text>. Spaces are allowed in <text>, but double quotation marks - to indicate a single - are not. <text> may be up to 80 Page 16 characters long and may include end-of-line characters, page feeds, or whatever you wish to improve the appearance of your output. Enough of the specifics, now we will try to let you know what these rules do. The LEGALANSWERS rule is used to constrict what the end user of your KB can use as responses. This is very useful to keep the end user on track, and to correct him in case of typos or misunderstandings. Using LEGALANSWERS can make testing your KB much easier and more complete. If LEGALANSWERS is omitted, then anything the end user types in is a valid response. The splat, (*), is used to terminate the LEGALANSWERS rule. Although the splat, by itself, is a totally valid <variable> or <value> we did not think many of you would want that as a valid response, so we use it as a terminator. In the ANIMAL sample KB, for example, we restrict responses to YES and NO. The GOAL rule specifies what you are looking for, that is, it determines what this consultation and KB are all about. The IF rules and the QUESTION rules are used by ESIE to try and find out what the <variable> of the GOAL should be set to. In the ANIMAL KB the GOAL IS TYPE.ANIMAL. The IF rules are the real meat of any KB. Here is how they work: the <variable> right after the IF is evaluated, and the evaluated value is compared to the <value> if the two are identical, then any AND parts are compared the same way. Comparison stops on any rule were an IF part or an AND part do not compare identically. However, if they are all identical then the rule succeeds and the <variable> immediately after the THEN is set to the last <value> specified in the rule. For example: if age is over.18 and status is alive then type.person is living.adult Let us assume that age has already been set to 'over.18', that status has been set to 'alive', and GOAL is TYPE.PERSON. ESIE begins looking through the KB, starting at the top, for IF rules that could satisfy the type.person goal. When it finds the above rule it determines that yes, age is over.18 and status is alive, so the rule succeeds and type.person is set to living.adult. At this point evaluation stops and ESIE makes its report and returns you to the top level. The QUESTION rules are evoked by ESIE when it has gone through the entire KB and can find no IF rule that satisfies what it is currently looking for. It then checks to see if it has a question that it can ask the end user so that it may determine what a <variable> should be. The <text> part of Page 17 the question is displayed and whatever the end user types in is what <variable> is set to, if the response is legal. If LEGALANSWERS has been specified, then the response is checked to see if it is one of legal ones. If it is not a legal response, then ESIE will list the possible responses, and ask the question again. This will continue until the end user has selected one of the legal answers. If it is legal, then the <variable> specified in the QUESTION rule will be set to the response. If LEGALANSWERS has not been specified, then whatever the user types in is legal. The ANSWER rule is used only when ESIE is done. After ESIE has found the <variable> in the goal statement he will display the <text> in the answer statement followed by the <value> evaluated from the <variable> in the ANSWER rule. You will note that you do not have to display the same <variable> as in the GOAL statement, but that you will often want to. Now for some limits. Just how much of this can you enter? Lots: Up to 50 <variables> for LEGALANSWERS. 1 and only 1 GOAL. Up to 400 IF rule lines. Up to 100 QUESTION rules. 1 and only 1 ANSWER. An IF rule line is a <variable> <value> pair. For example: if age is under.10 then type.person is child has two rule lines, while: if age is over.18 and status is alive then type.person is living.adult has three. Page 18 Some Sample Knowledge Bases In order to get you used to the ESIE rule structure, three sample KBs have been included on the distribution diskette. ANIMAL is a KB that plays "twenty questions" with you in order to find out what type of animal you are thinking about. Before typing in 'GO' to ESIE, after loading the ANIMAL KB, think of an animal you want ESIE to try and find. Answer the questions put to you about the animal and ESIE will find out what animal it is in far less than twenty questions. ANIMAL is a decision tree KB that is fully structured. This is what a session with ANIMAL looks like. The splats indicate output from ESIE: go Does your animal have a backbone? * yes Is the animal warm blooded? * yes Normally, does the female of your animal nurse * its young with milk? * yes Does your animal eat red meat? * yes Does your animal have finger wings? * no Does your animal have an opposing thumb? * yes Does your animal have a prehensile tail? * no Is your animal nearly hairless? * yes * I think you animal is a MAN * * I have completed this analysis. * * ==> * DOCTOR is a KB that is used to diagnose diseases in children. Do not take DOCTOR too literally, please. We are not physicians, and the information in the KB came out of a single book. The KB was built in about 8 hours. The DOCTOR KB is there just to show off ESIE and is not meant to replace your physician. DOCTOR is a decision tree KB also and is not fully structured. We coded DOCTOR and ANIMAL in two distinct styles in order to Page 19 demonstrate ESIE's capabilities. Take a minute to review them and learn how they operate. GLASS is rather special for us. First, we did not write it. We asked a friend to be one of our beta testers for ESIE and she came up with GLASS. She has no experience in AI whatsoever. GLASS demonstrates ESIE's ease of use. GLASS is used to give an evaluation of antique or depression era glass, which has gathered quite a following from what we understand. Page 20 Building Your Own Knowledge Base We assume that you have done all the necessary front work and are prepared with all the information you need. One thing that we can tell you about rule positioning. When you have a KB that is not fully structured, rule positioning can be important. You need only worry about rule positioning if the <variables> in the conclusions are identical, and the comparators are similar. This becomes obvious in the following two rule example: if has.fever is yes then type.disease is roseola if has.fever is yes and has.inflammed.ears is yes then type.disease is serious.ear.infection As ESIE is searching for 'type.disease' he comes across the first rule and invokes a QUESTION for has.fever. The end user specifies yes so ESIE concludes that type.disease is roseola and terminates this consultation. However, the child really had a serious ear infection, but ESIE never got that far. A better way to arrange the rules would be: if has.fever is yes and has.inflammed.ears is yes then type.disease is serious.ear.infection if has.fever is yes then type.disease is roseola Now, when ESIE encounters the first rule he invokes a question to find has.fever. Since the answer is yes he invokes the QUESTION to determine if the child has inflammed ears. Since the answer is yes, ESIE reaches the correct conclusion that the type.disease is a serious ear infection. In general, you only need to worry about rule placement in the IF catagory, when the <variables> in the conclusion are identical, and the comparators are similar. To build your own KB simply use your chosen text editor to edit a file and start filling the file with rules. We might suggest, dear reader, that you make a couple of "play" KBs just to get used to ESIE, before you really dig in with the real world ones. Follow the guidelines for ESIE outlined in The ESIE Rule Structure, and we are sure you will have no problem. Although we would love to help everyone out there who is trying to debug a KB, we will offer telephone support Page 21 only to the individuals who have paid the $145 price for ESIE. When you have enough rules in a KB to test what you have, simply start ESIE the way you would ANIMAL. When you get to the top level we suggest you turn trace on until you have the KB fully debugged. Then run through it, testing paths, using the GO command. Good luck! (we know, you are not superstitious, but it cannot hurt, can it?) Page 22 What Happens During A Consultation After ESIE has loaded the KB into internal structures, and the GO command has been issued, ESIE then pushes the GOAL onto a stack. The stack contains items to be searched for, currently looking for the one at the top of the stack. Then ESIE looks through the IF rules for a conclusion that matches the current stack. When one is found then ESIE looks through the comparators, one at a time, until one is found to be not equal to its value, or they are all found to be equal. ESIE checks each comparator by pushing it on the stack and continuing in this fashion. When ESIE can not find an IF rule in the KB with a conclusion identical to what is on the stack then ESIE turns to the QUESTIONs and LEGALANSWERS to get information from the end user. Any legal response is what the <variable> is set to. Often ESIE does not need to push anything on the stack as the comparator already has a value and it is equal to the value specified in the KB. In this case the rule succeeds and the conclusion <variable> is set to the <value>. In this way ESIE continues to get information and pop search items off the stack until it learns what the GOAL variable is, or until ESIE has searched the entire KB and found nothing that determines what the GOAL <variable> is. In the later case ESIE reports an error in the knowledge base and returns you to top level. In the former, ESIE reports the ANSWER <text> and <variable> and then returns you to top level. Page 23 Paying For and Obtaining the Next Version of ESIE Now comes the part we all hate to discuss. What is ESIE going to cost? Well, that is totally up to you. We happen to believe that most people are honest and will pay for something they find useful. We also believe that most software costs too much, and that all AI software costs way too much. We dislike copy protection schemes and there are none in ESIE. And we believe that you will want to see ESIE grow and be supported. If you feel that ESIE is useful to you, send what your conscience dictates. However, if you send at least $75 you will receive the most recent version of ESIE, free. If you send at least $145 you will receive: the most recent version of ESIE, fully commented source code for ESIE (ESIE was written in Pascal), our sincere thanks for your support, a copy of PC-Write (c) - a shareware full-feature text editor fully compatible with ESIE, and access to the help line, all free. Regardless of how you feel towards ESIE, we ask that you do two things: 1) Print, fill out and mail the file FORM so that we may keep improving ESIE, and 2) share copies of the distribution diskette with at least two people, preferably one of them outside your organization. We think of ESIE as living software: software that continues to develop and get better, more powerful. We believe ESIE is a useful tool as it is, but can be improved. However, support for living software must come from somebody. Even software authors and AI researchers cannot live on discovery and love alone. In shareware this support comes from you - the user. Mail and money for ESIE can be sent to: Lightwave; P.O. Box 16858; Tampa, FL 33617. Page 24 Planned Enhancements to ESIE As the current version of ESIE is being wrapped up and taken out of beta test, a few additional capabilities for ESIE have been suggested. Some of these sound like good ideas and are listed below. They will be part of ESIE version 2.0. 1. Adding the capability for introductory text to explain the KB. 2. Adding the capability for more terminating text, to explain the conclusion more fully. 3. Designating legal responses on a question by question as well as global basis. 4. Performing some type of automatic completion of responses, so the end user does not have to key in the entire response every time. A. We are not so sure about this one. Why not just include those as part of the LEGALANSWERS? 5. Numerical computations. 6. A 256 KB RAM ESIE. 7. A 512 KB RAM ESIE. 8. A 1 MB RAM ESIE. Page 25 Bibliography Classification of the Animal Kingdom, An Introduction of Evolution; by Kenneth Jon Rose; David McKay Company, Inc., New York, 1980. The Common Sense Book of Baby and Child Care; by Benjamin Spock, M.D.; Duell, Sloan, & Pearce, New York; 1957.