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XXXPERT V11 Copyright 1987 Stephen Thurber 1926 Labrador Lane Vienna, VA 22180 All rights reserved INTRODUCTION XXXPERT is an expert system development facility which includes an editor, file manager and expert systems inference engine packaged together in one integrated environment. You can use XXXPERT to develop expert systems that use rules you write in an English language syntax. You can develop expert systems that will aid you and others in doing things that you would not be able to do consistently as well without XXXPERT. XXXPERT allows you to define expert knowledge just once then apply it repeatedly time after time as a stand-alone expert system or integrated with other applications software and other files. There is essentially no limit to the size and complexity of expert systems that may be constructed with XXXPERT. XXXPERT is very fast and allows rulebases (expertise) to be chained together into an arbitrarily large system of knowledge. XXXPERT is a product that is distributed under the 'shareware' concept. Please see the next chapter for further explanation. SHAREWARE XXXPERT is distributed under a concept commonly known as 'shareware'. This approach to software distribution allows you to receive and try software then pay for it according to the value you have received from it. If you feel that, after trying XXXPERT, it has given you some value, please contribute according to your conscience and level of satisfaction. Shareware operates largely on the honor system with a contribution being your vote for continued development of this product. If you contribute $49.00 or more, you will receive a copy of the current updated versions of XXXPERT and CONSULT, as well as a USER- ID that entitles you to future releases for a modest renewal royalty (currently $5.00 per release) and, in addition, you will receive a $10.00 rebate each time someone else makes a $49.00 or larger royalty contribution from a copy of your own paid copy of XXXPERT using the Form provided on your paid updated disk. (Rebates are limited to the amount of your contribution.) Continued commercial, non-profit and government organization use is prohibited unless a $49.00 royalty has been paid for each copy of XXXPERT in use (ie: according to the common analogy with books--one reader/user at a time per copy). Site licenses are available for a royalty of $2000.00, however, for large users. Please address correspondence and contributions to: XXXPERT,V11 c/o Stephen Thurber 1926 Labrador Lane Vienna, VA 22180 XXXPERT DESIGN PHILOSOPHY A few words on the design philosopy underlying XXXPERT will probably aid you gretly in using it well. Therefore I will digress a bit before returning you to a nuts and bolts discussion of product features. The following are the key points of XXXPERT's general design approach and the reasons for each: 1. XXXPERT and CONSULT are conceived to be complements to your existing stable of software. Therefore the product concentrates on delivering only those features which are uniquely an aspect of expert systems while providing links and tools to make the product cooperate with the rest of your PC software. This is helpful since you probably already know how to use an existing set of software (including DOS, batch files, a database, spreadsheet or whatever) and would like to spend a minimum amount of time on learning new quirks of other software. It would therefore be wasteful of your time (and mine) to duplicate commonly available software functions here in this product. For this reason, you will not find a new database, spreadsheet, or batch file syntax introduced here. Instead XXXPERT adds only the new features you need to quickly add expert systems capabilities to your overall PC applications environment. You will not need to learn new syntax for features duplicating those you already have on your PC. 2. There is a wide variety of other software out there, and any of it may interest you as a complement to this product. XXXPERT and CONSULT therefore are designed to link to other software through standard DOS files, DBASE 3 (r) files and LOTUS (r) .WKS spreadsheet files, allowing you to use them with virtually any other PC software. 3. You probably already know how to use DOS batch files, so this product does not introduce another 'script' language for you to use. Instead, we attempt to make it easy to build systems using DOS batch files to script together your application with this product and any other type of product (or user-written program) of your chosing. This approach is easy, familiar and frugal with PC memory. 4. This product has an integrated development approach that is similar to popular new programming language compilers in that coding, compilation, testing, debugging, and operating expert systems may be done without leaving XXXPERT. This greatly speeds the development process for expert systems. A CONSULT "run-time" system lets you build expert systems technology into your applications (with XXXPERT being essentially invisible to the user.) A MINICON run time system is included for situations wherein memory is tight. HARDWARE REQUIREMENTS XXXPERT requires an IBM (r) or closely compatible computer with DOS 2.1 or above, 256k RAM or more, and a monochrome or color monitor. Additional RAM may be needed to use the RUN@ feature that allows you to run other programs within XXXPERT and CONSULT (depending on the size of the program you intend to run.) MINICON can run in as little as 115k, however. THE XXXPERT DISK Please feel free to make as many copies of the XXXPERT disk as you wish, PROVIDED THAT ALL OF THE FILES ON THE DISK ARE COPIED WITHOUT MODIFICATION. You may give copies of the disk to anyone, and are encouraged to do so as long as you do not distribute any XXXPERT file without the others. XXXPERT files include: XXXPERT.COM the integrated expert system CONSULT.COM the consult-only system XXXPERT.DOC this document XXXPERT.FRM a correspondence form CAR.R car diagnosis rules sample CAR.K compiled car rules CAR.A car diagnosis asks sample CAR2.R another car rules sample CAR2.K compiled car2 rules CAR2.A another car asks sample CREDIT.R credit authorization rules CREDIT.K compiled credit rules CREDIT.A credit authorization asks CHEESE.R cheese selection rules CHEESE.K compiled cheese rules CHEESE.A cheese selection asks READ.ME introductory notes INSTALLING XXXPERT XXXPERT should be installed on a diskette along with a copy of your DOS system. The easiest way to do this is: 1: Insert your DOS diskette in drive A. 2: Insure that A is the default drive. 3: Insert a new floppy disk in drive B. 4: type: format b:/s 5: press return. 6: Insert the XXXPERT distribution disk in drive A. 7: type: copy a:*.* b: 8: press return. The new disk will then be ready to use as your expert system disk. Alternatively, XXXPERT may be installed on your hard disk. DEVELOPING RULES XXXPERT is a rule-driven system. Rules are simply statements of logic that you wish to have applied to the area of expertise your rules are to address. These statements are written in English and abbreviations thereof. The first rule statement in a rules file must be on a line by itself (and on the first line of the file). This statement must specify the name of the goal for the consultations to be performed with the set of accompanying rules. In the CAR rulebase the goal is PROBLEM since the purpose of the CAR consultation is to determine the probelm with the car. The goal in a rule file is always an identifier (a fieldname or variable) to name the object of the consultation process. XXXPERT will use all the subsequent rule statements to seek a value for the goal. Each rule statement after the first must be of the following general form: IF ==== EQ ---- AND ==== EQ ---- THEN ==== EQ ---- where ==== indicates an identifier (a fieldname or variable) and ---- indicates a state (a constant or value). For example, to express the knowledge that: baby's diaper should be changed when baby is crying and diaper is wet, the rule could be coded: IF DIAPER EQ WET AND BABYACT EQ CRY THEN ACTION EQ NEW.DIAPER The EQ in XXXPERT's rules syntax stands for equals. The keyword NE may be used to express an inequality (not equals) situation in otherwise similar syntax. For field values that are numeric, the GT (greater than), GE (greater than or equal to), LT (less than), and LE (less than or equal to) keywords may also be used as appropriate. The part of the rules statement format shown above as: AND ==== EQ ---- is optional as well as repeatable. Thus the following rule examples are all valid and meaningful (but different, of course!): IF DIAPER EQ WET THEN ACTION EQ NEW.DIAPER IF DIAPER EQ WET AND BABYACT EQ CRY AND HAD.NO.NAP EQ YES THEN ACTION EQ GETHELP A set of rules may be constructed in this way to handle an arbitrarily complex set of expertise. The CAR.R file contains an example set of rules for diagnosing an automobile that won't start. The CHEESE.R file contains an example set of rules for choosing cheese to go with a course of a meal. Other examples may be found in the CAR2.R and CREDIT.R files. You may use the DOS 'type' command to view these files or you may use the XXXPERT rules editor after doing a Getfile for CAR, CHEESE, CAR2 or CREDIT respectively. Identifiers (fields or variables) may be any name or other collection of letters, punctuation and numbers in a string up to 16 characters in length. Imbedded blanks are not allowed. Constants (values) are subject to these same restrictions. Constants may be words or numbers and if numeric they may be integer (ie: 1) or real (ie: 123.45). A single file of rules may consist of up to 400 rule elements in this version of XXXPERT. A rule element is generated by each IF and by each pair of ANDs. Rulebases with more than 400 rule elements can be effectively implemented through multiple related rulebases. Techniques for achieving this are discussed in the section on EPLIOGUE and in the section on extended input/output. Rules are coded in free format with multiple rules per line or multi-line rules as desired. XXXPERT supports sets of rules up to 300 lines per file in this version of XXXPERT. This limit is also easily circumvented through multiple related rulebase techniques. NOTE: Rules must be created in upper case, and this requirement is enforced by the XXXPERT editor. (The editor uses upper case regardless of the case you type.) DEVELOPING ASKS XXXPERT will need certain information from the user in the course of any given consultation session depending on the rules being used in that session. The "asks" define how XXXPERT should ask the user (consultee) for such information. In general you should code an ask for each identifier that appears in the left-hand-side of a rule (before the THEN) unless it also appears in the right-hand- side of another rule. XXXPERT asks consist of two lines each. The first line of each ask must contain the identifier to which it applies, and the identifier must begin at the beginning of the line. The second line of each ask must contain one of the following: 1) A text prompt that XXXPERT should use to request a value from the user for that identifier; or 2) A specification for a worksheet cell from which to retrieve the information; 3) A specification of a database .DBF file and record selection specification for a record containing a value for the ask; or 4) A specification for a program to run which will provide the necessary data to XXXPERT. Thus, odd-numbered lines of the asks (first, third, fifth, etc.) will contain identifiers while even-numbered lines will contain the associated text prompt for the user, a worksheet specification, a database specification or a program specification. To define a text prompt for an ASK you merely place the text of the desired prompt on the second line of the ASK. XXXPERT and CONSULT will automatically edit a user response to the prompt to insure that the response in consistent with at least one rule in the rulebase being used. In the event that the response is invalid there will be a warning message and the prompt will be repeated for the user. To define a worksheet reference you begin the second ASK line with the keyword: WKS@ followed by the name of the worksheet followed by the desired cell. To refer to the C25 cell of a worksheet named BUDGET.WKS for an ASK of the XXXPERT field named SALES you would use the following statements: SALES WKS@ BUDGET C25 Only standard .WKS format files are supported by this feature. If the attempt to retrieve worksheet data should fail, a value of NA will be returned for the field associated with the ASK. NA should therefore not be used as a value in RULES. To define a database reference you begin the second line of the ASK with the keyword: DB3@ followed by the database file name followed by a selector field followed by a value to search for in the selector field. The DB3 interface will look for a record which has the stated value in the specified selector field. Upon finding such a record, the value in that record for the ASKed field in the record will be given to the ASKed field in XXXPERT. To refer to the record containing 1987 in the YEAR field of a database named BUDGET.DBF for an ASK of the XXXPERT field named SALES you would use the following statements: SALES DB3@ BUDGET YEAR 1987 Only standard .DBF format dBASE 3 (r) files are supported by this feature. If the attempt to retrieve database record should fail, a value of NA will be returned for the field associated with the ASK. NA should therefore not be used as a value in RULES. To define a program to run under XXPERRT or CONSULT to provide the data needed for an ASK you must begin the second line of the ASK with the code: RUN@ followed by the name of the program to be run. To run GETDAT.COM you would use the following statement on the second line of the ASK: RUN@ GETDAT The program that you run must be a .COM format file and must not require more memory than is left available on your machine after XXXPERT or CONSULT has been loaded in. The program that you run must place a value for the AKSed field in a file named RUN.I (this is where XXXPERT and CONSULT will be looking for it). The program that you run must also be well-mannered enough to not disturb DOS, CONSULT or XXXPERT-owned parts of your computer. If your program is too large or ill-mannered your consultation will crash or behave unpredictably. If the attempt to retrieve the program's data should fail, a value of NA will be returned for the field associated with the ASK. NA should therefore not be used as a value in RULES. XXXPERT supports sets of asks of up to 600 lines per file. Once you create a set of asks you should save it under the same name as the rules that you intend to use them with. See CHEESE.A, CREDIT.A, CAR.A and CAR2.A for asks examples. NOTE: Asks must be created in upper case, and this requirement is enforced by the XXXPERT editor. PROLOGUE, INTERMISSION AND EPILOG It may be desirable for certain explanatory information to be displayed in the course of a consultation in the XXXPERT environment. The prologue feature, intermission feature and epilogue feature are all provided in XXXPERT to this purpose. Prologue provides the ability to define a screen of text to be displayed at the beginning of a consultation with a given set of rules. Intermission provides the ability to define a screen of text for any given set of rules that is to be displayed at the end of a consultation but just prior to the presentation of the XXXPERT conclusion. Epilogue provides the ability to define a screen of text for any given set of rules that is to be displayed after the presentation of the XXXPERT conclusion and that may vary depending on the specific conclusion that is reached by XXXPERT. You may use the prologue feature by entering the editor (as described in the next chapter) to create a prologue screen under the same file name as the rules you intend to use it with. The screen contents may be entirely of your chosing up to the 20 line limit provided for the prologue screen for any given file group (set of rules files.) You may use the intermis feature by entering the editor (as described in the next chapter) to create a intermis screen under the same file name as the rules you intend to use it with. The screen contents may be entirely of your chosing up to the 20 line limit provided for the intermis screen for any given file group (set of rules files.) You may use the epilogue feature by entering the editor (as described in the next chapter) to create an epilogue screen for each conclusion (value for the rules goal) that you want to have in your rules file. The format of the epilogue file is similar to that for asks in the sense that you must put a value on a line by itself (at the beginning of the line) to identify the start of the text associated with a given possible conclusion (goal value). The text to be displayed when that goal value is selected as the XXXPERT conslusion must be coded on the immediately subsequent lines (up to 20 lines). The end of the text associated with a given goal value (conclusion) is delimited by placing the same goal value on a line by itself at the beginning of the line. An epilogue file for 2 possible goal values (a conclusion of YES and a conclusion of NO) might look like this: (see next page) YES THIS IS THE TEXT I WANT TO DISPLAY FOR THE YES CONCLUSION FOR MY EPILOGUE YES NO THIS IS THE TEXT I WANT TO DISPLAY FOR THE NO CONCLUSION FOR MY EPILOGUE NO The EPILOGUE facility also allows you to link to another set of rules depending on the results of the current consultation. This feature (called chaining) is available only in the CONSULT program (see the chapter on CONSULT later in this manual) and it allows the construction of expert systems with essentially any number of rules. Chaining is the capability to link multiple rule files serially within a single CONSULTation run. This capability is implemented through the CHN@ command in the EPILOGUE facility. CHN@ allows you to name a rulebase to invoke and causes the results of the current consultation to be passed on to the consultation for the named rulebase. The EPILOGUE facility allows for an individual CHN@ rulebase specification for each possible consultation result, therefore the rulebase used for the next consultation may be varied according to the outcome of the current consultation. There is no limit to the number of levels rulebases that may be involved in this type of arrangement. To specify a set of rules to be chained-to after the current consultation is completed you include a CHN@ keyword as the first 4 characters in any of the epilogue lines for the value of the goal to which chaining is to apply in the chained-from consultation. CONSULT will recognize the keyword, suppress display of that epilogue line and use it as a specification for chaining. The CHN@ should be followed by at least one space, then the name of the rules file to use for the next stage of consultation. For example, to chain to the XYZ rules when the value for the current consultation goal is ABC an EPILOGUE with no other display lines would look like this: ABC CHN@ XYZ ABC Other lines of information could have been included in the EPILOGUE and would have been displayed normally. If more than one CHN@ line is included in the range of lines for one value of the goal then the last CHN@ line so included will prevail. The use of CHN@ overrides the usual convention on .O files inn the CONSULT program (see the section on extended input/output later in this manual). Instead of observing the .O file convention, a .I file is created under the name of the chained-to rules (ie: XYZ.I in the example above). This file contains the name and value of the goal field for the chained-from rules so that the chained-to consultation rules may be primed with data from the goal of the chained- from rules. Using this feature you can create a network of sets of rules that comprise a knowledge-base that may be as large as one wishes. USING XXXPERT You may start XXXPERT by booting your system with the XXXPERT disk in the default drive A. When the system has completed the boot process XXXPERT may be started by typing: xxxpert and pressing the return key. XXXPERT will start and a banner screen will appear welcoming you to the XXXPERT system environment. To continue you should press return once again. At this point XXXPERT's main menu will display, offering the following options: Getfile Editfile Consult Keep Trace Xref Output Quit You may select the option you need by typing the first letter of the name of the option. The letter may be typed in either upper or lower case. Alternatively, you may use the right-arrow and left-arrow keys to position the highlight box over a menu selection and press return to activate that selection. These are conventions that apply to all menu selection options throughtout the XXXPERT product. GETFILE The main menu's Getfile option brings up a prompt for a filename and loads the file group you specify into the file areas within XXXPERT. This allows you to retrieve a previously-created set of inference rules, asks and other information so that you may modify and/or consult with them. If you make a error in typing the filename you may use the backspace (or left-arrow) key to correct it. Once the file name has been typed press the return key to perform the get. Do not include an extension in the file name (ie: to retrieve the sample car rules and asks, CAR is correct, CAR.R is incorrect.) XXXPERT will retrive both the rules and all related files (including asks, prologue, intermission and epilog, if present) for the specified name. In the CAR example above, both CAR.R and CAR.A would be reteived by requesting CAR. EDITFILE The main menu's Editfile option brings up a menu of these suboptions: Rules Asks Prologue Intermis Epilogue Quit The rules option starts the rules editor subsystem and displays the first screen of rules from the current file group. If the current filegroup's set of rules is empty, the edit screen will be blank (this will be the case if Getfile has not been successfully performed and no previous rules edit has been performed since XXXPERT was started.) Once in the rules editor you may type in XXXPERT rules in free format. The editor always stores rule information in upper case except for numbers and punctuation which (for the ones that are allowed) are stored in the way they are typed. The home, up-arrow, left-arrow, right-arrow, end, down-arrow, pagedown, and pageup keys may be used to move the cursor position accordingly. The backspace key performs the same function as the left-arrow. The del key may be used to delete characters and the ins key may be used to switch to and from insert mode in the editor. (An indicator in the bottom line of the edit screen notes whether the editor is in insert mode or overtype mode.) A line may be deleted by pressing the D key while the ctrl key is being held down. The return key will advance the cursor to the start of the next line on the screen except while in insert mode, in which case the return key will insert a blank line in front of the line in which the cursor is currently positioned. The slash key (/) may be used to bring in a pop-up menu for other functions as described in the EDITOR POP-UP MENU section below. The asks option starts the asks editor subsystem and displays the first screenful of asks from the current file group in XXXPERT. Asks edit performs functions in the same manner as rules edit, except that the editing is with respect to asks rather than rules. The prologue option starts the prologue editor subsystem and displays the prologue screen for the current file group in XXXPERT. Prologue edit functions similarly to rules edit except that XXXPERT limits the prologue to 20 lines of text and the editor enforces this limit. The intermis option starts the intermis editor subsystem and displays the intermis screen for the current file group in XXXPERT. Intermis edit functions similarly to rules edit except that XXXPERT limits the intermis to 20 lines of text and the editor enforces this limit. The epilogue option starts the epilogue editor subsystem and displays the first epilogue screenful for the current file group in XXXPERT. Prologue edit functions similarly to rules edit. Quit returns you to the XXXPERT main menu. EDITOR POP-UP MENU In sny edit session, the slash key may be used to invoke a pop-up menu that contains the following options: Continue Save Zap Quit Continue removes the pop-up menu and continues the edit process. Save allows you to save edited material (rules or asks) to disk under a filename of your choosing. When specifying a filename do not include an extension. XXXPERT will add a .R extension for files saved during a rules edit, a .A extension for files saved during an asks edit a .P extension for files saved during a prologue edit, a .N extension for files saved during an intermis edit, and a .E extension for files saved during an epilogue edit. Files that you intend to use together as a file group (set of rules-realted information) should be saved under the same name (ie: I have created all the CHEESE consultation files under the name CHEESE, allowing XXXPERT to provide the extensions, resulting in DOS filenames of CHEESE.R, CHEESE.A and CHEESE.K for the CHEESE rules, CHEESE asks, and CHEESE keep respectively). The role of .K files is explained later. My CHEESE example does not use prologue, intermission or epilogue. Zap clears out the contents of the area currently being edited. Note that Zap has no impact on disk files by itself. Only the data inside XXXPERT is cleared unless you subsequently do a Save. Quit takes you back to the Editfile menu, terminating the current edit process. The edit data is retained in XXXPERT but is not saved to disk unless you do a save before the quit. CONSULT The main menu's Consult option uses the current set of asks and rules in XXXPERT to conduct a consultation with you on the basis of the logic you defined in those rules and asks. Based on your answers to the questions XXXPERT poses, a recommendation will be made according to the inference rules. You must press the return key with each reply you provide to XXXPERT's questions. You may correct any error in an answer prior to pressing return by using the backspace key or the left-arrow key. You may terminate the consultation at any prompt by pressing the escape key (ESC.) Please remember that XXXPERT's conclusion and recommendation will be based solely on the rules you provide. The quality of the recommendation is therefore directly dependent on the quality of inference rules you develop. Before using XXXPERT or CONSULT to make any important decision you should thoroughly test the expert system you have built to be sure that XXXPERT and CONSULT give you the results you intend. KEEP The keep command on XXXPERT's main menu may be used to create and store (on disk) a compiled form of the currently retrieved set of rules. This compiled form may later be used by the CONSULT program (CONSULT.COM) to immediately conduct a consultation session with that set of rules (and associated files) without the need to see the XXXPERT banner screen, use menus, perform getfiles, and wait for compilations. This greatly aids in the creation of applications involving multiple rulesbases, multiple consultations and/or other software (besides XXXPERT). See the CONSULT PROGRAM section later in this manual. TRACE The trace command is available on the main menu to switch trace mode on and off for XXXPERT. Requesting trace will turn the trace mode on if it is currently off, and vice- versa. Consultations that are run while trace is on will be accompanied by a trace-style debugging report on the inference rules being used by XXXPERT's reasoning process as the consultation progresses. This allows you to test the rules you develop in an easy and visible way. XREF The XREF command on XXXPERT's main menu may be used to display an analysis report on the currently reteived set of rules. This report consists of three parts: the listing, the cross reference and the warnings analysis. The listing shows the current set of rules in a stadard format labeled with line numbers to aid in use of the cross reference part of the report. The cross refernce shows each identifier in the rulebase along with the line numbers for each rule line in which that identifier is used. The warnings analysis reports instances in the current set of rules where a field value is created but never used or vice-versa. That is, a warning message will be issued for each field value that appears in a THEN but is not used in any IF and for each field value that is used in an IF but does not appear in any THEN. Certain instances of the above are screened out, however as follows: 1. A field value that appears in a THEN for the goal will not be subject to warnings (since goals are not normally used in IFs. 2. A field value that appears in an IF will be subject to warnings only if the field identifier appears in at least one THEN (with another value). (Field identifiers that never appear with any value in any THEN are assumed to be included in an ASK.) OUTPUT The output option on XXXPERT's main menu may be used to access a selection screen that controls whether TRACE and XREF output are directed to the screen (by default) or to the first parallel printer port (by option). CONSULT PROGRAM The CONSULT program allows you to conduct a consultation session using a set of rules for which a KEEP has previously been executed in XXXPERT. CONSULT goes directly into consultation without any intervening screens, menus, compilations or prompts. CONSULT may be started by typing CONSULT followed by the name of the 'kept' rules that are to be used. The example below would initiate a consultation for the CAR rules using the 'kept' car rulesfile: CAR.K and the CAR asksfile: CAR.A: consult car This type of command may be used at the DOS prompt or within a BATCH file on your DOS system. EXTENDED INPUT/OUTPUT The CONSULT program has a feature called extended input/output that greatly facilitates the linking of XXXPERT rulebases with each other and with information from other systems. Extended input/output allows data to be passed into a consultation session and it allows the conclusion of a consultation session to be passed out to another consultation session or another system. The two most likely uses for this feature are: 1- linking together multiple related expert systems that would be too large to be integrated into a single rulebase (either because of human limitations or XXPERT limitations) and 2- linking expert systems consultations in with other PC-based applications and data. You may pass data values into a consultation for any of the rule fields by arranging for the desired values to be in a file when CONSULT is started. The file name should match the rule file name except that the extension must be: .I instead of: .R. Thus to run a consultation passing data in to be used with the CAR rules you would create a file named CAR.I and start the session by issuing CONSULT CAR at the DOS prompt (or within a batch file). Within the .I file the data fields and corresponding data values should alternate lines in a manner similar to the ASKs files. The first line should contain the first field of interest, the second line a value for that field, and so on. Thus to inform the CAR consultation that it should use a value of 44 for TURNS you would create a CAR.I file that looks like this: TURNS 44 Turns is the field of interest and therefore is on the first (or any odd-numbered line) and 44 is the value for TURNS so it is on the line immediately after TURNS. At the end of any CONSULT session a value will be determined for the goal (assuming the rulebase contains sufficient knowledge). CONSULT always then creates a file (with a .O extension and a name matching the rule file name) that contains the goal field name on the first line and the value for the conclusion on the second line. This data may be used by other systems or by other CONSULT sessions if desired. Note that (not coincidentally) the .O file has a format consistent with .I file requirements. This allows you to rename a .O file to an appropriate .I name and use it as input to a consultation session (the renaming could be done in a batch file, for example). You can, therefore, use these files and the DOS batch file capability to link multiple rulebases through multiple consultations in combination with any other software of your choosing. This allows you to build arbitrarily complex expert systems and integrate them with non-XXXPERT appplications using familiar DOS facilities! A DOS batch file to link the CAR rulebase with another rulebase (CARFIX, for example) might look like this: ERASE CAR.O ERASE CARFIX.I CONSULT CAR RENAME CAR.O CARFIX.I CONSULT CARFIX Such a batch file would run a CAR consultation, pass the conclusion to CARFIX and run the CARFIX consultation with the conclusion of the CAR consultation as input (that otherwise would need to be obtained from the user with an ASK.) The ERASE commands have been included to prevent the possibility of using files left over from preious runs. The .O files are not created if CONSULT finds that its rulebase does not provide sufficient knowledge to make a recommendation, so the use of ERASE may be key to insuring the integrity of your overall batch job. With the above batch file as written, the first consult will report its results to the screen as well as to the CAR.O file. It may not always be desirable to report intermediate results in a series of CONSULTs and if this is the case, screen output may be suppressed by including a second parameter (X) in the CONSULT command after the rule file name. In the above example the output from the CAR consultation could have been suppressed by rewriting the CONSULT command in the following way: CONSULT CAR X Note that these various file sharing techniques could be used to share data with spreadsheets, databases, graphics packages or any other PC application. MINICON MINICON is a version of CONSULT that requires much less memory (RAM) to run but lacks the ability to perform any of the ASK functions. It is very useful if you want to integrate an expert system facility inside another application without taking much additional memory (about 115k or so). All data needed by MINICON to perform the consultation must already be in a .I file since ASKs are not available. MINICON may be used by most any application that has the ablility to run external programs.