Edited: MJS May 3, 1983 10:06 AM File: {indigo}loopsmoviescript.bravox12(635)\f1 Loops Movie Script x12e24c\f9b The Loops Design Teamx12e12c\f6 Copyright c 1983 by Xerox Corporationx12e12\10f3 1f0 Special effects: Title slide white on blue background. Music and increasing crescendo of sound from Knowledge competition in Background.d3648x12e12j\f1bi15I d3648x12e12j\u58U Knowledge Programming in Loops: Highlights from an Experimental Coursed3648x12e12c\b70B Mark Stefikd3648x12e12c\b Daniel G. Bobrowd3648x12c\b Sanjay Mittald3648x12c\b d3648x12e12j\u59U Special effects: Fade To A white title on a blue background.d3648x12e12j\f1bi15I d3648x12e12j\u58U Knowledge Systems Aread3648x12e12c\b Xerox Palo Alto Research Centerd3648x12e12c\b Copyright c 1983 by Xerox Corporationd3648x12e12c\f1 10f3 1f1 26f0 d3648x12j\u58U x12e12\f1b Sound: Music fades. Crowd noise remains low. Stefik speaks over the crowd noise.x12e12\f1b Script for Stefik: d3648x12e12j\f1bi18I View: Display of game board. d3648x12e12j\f1bi4I Film Clip: xx-xx-xx to xx-xx-xx Fade to closeup of the gameboard showing a truck going to a stop where it is robbed by Bonnie or Clyde. Remark in crowd about being robbed. Pull back, getting a brief view of full game board on the screen.d3648x2e12j\i10I2b8B4b8B2f1 207f0 This may appear to be a typical a video game.d3648x12e12j Actually, something much more unusual is happening.d3648x12e12j You are watching a knowledge competition.d3648x12e12j\19i21I What looks like a competition between people is actually a competition between knowledge systems -- knowledge-based computer programs.d3648x12e12j View: Crowd shot. d3648x12e12j\f1bi4I Film Clip: xx-xx-xx to xx-xx-xx Fade to view of crowd gathered around screen. Watch for 5-10 seconds. Sound fade though view remains. d3648x2e12j\i10I2b8B4b8B1f1 102b2f0B These people have just spent three days taking a course about Loops -- a knowledge programming system.d3648x12e12j The final problem in the course was to program a knowledge based player.d3648x12e12j Instead of playing the game with a joystick, each team created a computer program -- a sort of independent trucker -- to play the game for them.d3648x12e12j\95i19I They had to write rules to guide their players in the situations that arise in the simulation world. d3648x12e12j View: of Stefik in his office. The following slide appears momentarily underneath Stefik. d3648x12e12j\f1bi4I d3648x12e12j\u58U Mark Stefik Knowledge Systems Area Xerox PARC Loops Logod3648x12e12c\b45i14f1B10f0b d3648x12j\u58U Knowledge programming is part of Artificial Intelligence.d3648x12e12j It is concerned with the techniques for representing knowledge in computer programs.d3648x12e12j Knowledge programming is important in many applications of AI -- where the problems are messy.d3648x12e12j\88i5I Like many things in real life -- pat solutions, or simple mathematical solutions just aren't good enough.d3648x12e12j Things break. Information is missing. Assumptions fail.d3648x12e12j To cope with messiness, AI researchers have found that large amounts of problem-specific knowledge are usually needed.d3648x12e12j This places a premium on advanced techniques for representing and testing such knowledge in computer programs.d3648x12e12j Very few people have been trained to build knowledge systems.d3648x12e12j "Training" today usually requires several years of study at one of a handful of universities.d3648x12e12j A group of us in the Knowledge Systems Area at Xerox PARC are trying to shorten this training time.d3648x12e12j We are developing new tools and methods.d3648x12e12j Our goal is to increase the impact and scale of Artificial Intelligence by simplifying methods of Knowledge Programming -- and making those methods more widely accessible.d3648x12e12j View: Move to Closeup of Loops Logo. MJS pointing to it with a pointer.d3648x12e12j\f1bi5I d3648x12e12j\u58U In doing this, we have created a knowledge programming system called Loops.d3648x12e12j We use this icon as an aid in explaining Loops.d3648x12e12j Loops is a a programming system that integrates several programming paradigms.d3648x12e12j (point) The first paradigm is procedure-oriented programming of Interlisp. In this paradigm, big programs are built up from little ones by making subroutines. Data and programs are kept separate. Most computer languages in the world are like this.d3648x12e12j\f1b9f0B (point) The second paradigm is object-oriented programming. In this paradigm, the world is made up of objects -- combining both procedures and data. Objects communicate via by sending messages to each other. Standardized protocols enable different kinds of objects to respond to the same kinds of messages. Big objects are built out of smaller objects.d3648x12e12j\f1b9f0B (point) A third paradigm is data-oriented programming -- used for programs that monitor other programs. You can think of this as a way of connecting probes into the variables of a program. The probes can trigger additional computations when they sense changes in the data. In this paradigm, as in the others, Loops provides appropriate methods of composition. d3648x12e12j\f1b9f0B Loops currently provides one other paradigm -- called rule-oriented programming. This paradigm is specialized for representing decision-making knowledge in the form of rules.d3648x12e12j In Loops integrates (point at ring) these paradigms are all integrated -- to be used together in building a complete program.d3648x12e12j\20f1b15f0B View: Fade Back to Mark Talkingd3648x12e12j\f1b To test the effectiveness of the our methods for building knowledge systems, we taught an experimental course. In the two versions of the 3-day course that have been run so far, the results have been very encouraging. d3648x12e12j Everyone in the course was able to learn enough of the Loops programming environment to formulate the knowledge for their system, and interact with Loops to modify and debug their systems. d3648x12e12j The problem setting used in the course is a simulated economic model called Truckin -- brought to life in the video display that you saw.d3648x12e12j\76i7I The knowledge systems built by the students had to plan routes for buying and selling commodities, and avoiding hazards of the simulation world.d3648x12e12j At the end of the course, we had a knowledge competition, in which all of the programs competed with each other. d3648x12e12j\35i21I This is the story of the experimental course, told from the viewpoint of one of the participants.d3648x12e12j Time 02:10x12e12\f1b10f5B View: Course participant in hallway outside the Loops class room (AH). d3648x12e12j\f1bi4I Special Effects: Austin's name overlays near bottom of screen for a few seconds.d3648x12e12j\f1bi16I d3648x12e12j\u58U Austin Henderson Cognitive and Instructional Sciences Area Xerox PARCd3648x12e12c\69i d3648x12e12j\u58U Script for Austin: d3648x12e12j\f1bi18I In February, I took the Loops course offered by my colleagues. I was curious about how the ideas in Loops would apply to both the art of programming, and to Trillium. Trillium is an internal Xerox project for designers who are not programmers. It helps them to develop interactive interfaces to copiers. d3648x12e12j Twenty two people were in my course. Since I am from Xerox, I was a somewhat atypical participant. -- Most of the people came from research laboratories such as SRI International or Lawrence Livermore or Stanford University, or startup AI companies like Applied Expert Systems and Teknowledge. d3648x12e12j Also -- I already had experience with the exploratory programming languages Interlisp and Smalltalk, and with knowledge representation languages like Klone. Loops integrates several different programming paradigms -- that is, styles for organizing information. It was being touted as combining the best features of many of the systems that I already knew about. I wanted to see this for myself.d3648x12e12j View: Camera follows Austin walking towards the classroom door. Focuses momentarily on the wall sign, and then back to Austin.d3648x12e12j\f1bi5I d3648x12e12j\u58U The Loops Coursed3648x12e12c d3648x12e12j\u58U d3648x12e12j The course was a combination of lectures and exercises using Loops on Xerox computers. The first lecture was about object-oriented programming in Loops.d3648x12e12j Time 03:10x12e12\f1b10f5B Special Effects: Fade to Loops Color Saturn Logo with subtitle as follows:d3648x12e12j\f1bi16I d3648x12e12j\u58U Lecture 1d3648x12e12c Object-oriented Programmingd3648x12e12c d3648x12e12j\u58U Film Clip: 01-03-24 to 01-04-16. DGB. "Good Morning. please ask questions."d3648x12e12j\i10I2b8B4b9B1f1 42f0 Special Effects: Subtitle appears for a few seconds.d3648x12e12j\f1bi16I d3648x12e12j\u58U Daniel G. Bobrowd3648x12e12c Knowledge Systems Aread3648x12e12c Xerox PARCd3648x12e12c d3648x12e12j\u58U Film Clip: 01-06-00 to 01-07-31. DGB. Outline of talk.d3648x12e12j\i10I2b8B4b9B2f1 22f0 Film Clip: 01-25-23 to 01-25-59. DGB. Bob Blum question and answer.d3648x12e12j\i10I2b8B4b9B2f1 35f0 Film Clip: 02-17-47 to 02-18-27. MJS. "Pick partners for exercises."d3648x12e12j\i10I2b8B4b9B2f1 36f0 Time 07:00x12e12\f1b10f5B View: Fade to Austin sitting at a workstation. A course notebook is at hand, open to the pages of the first set of exercises. Interlisp-D manuals are also at hand.d3648x12e12j\f1bi5I The workstation screen shows the standard set-up for the Loops Demo. Second camera is on the screen (or a slave screen). d3648x12e12j\f1b Script for Austin.d3648x12e12j\f1bi18I After the first lecture, we were grouped into teams of 2-3 people to do the exercises on the computer. Our first set of exercises was about the Loops programming environment and object-oriented programming.d3648x12e12j The Loops user interface makes extensive use of interactive graphics. One of the standard ways of accessing objects in Loops is to use a browser. A browser is a program that enables a user to "browse" through information in a knowledge base. A particular kind of browser -- a class browser -- shows the inheritance relationships between classes.d3648x12e12j\277i18I View. Fade to second camera on a slave screen. The workstation screen shows the standard set-up for the Loops Demo. Perhaps a split-screen with one camera on the mouse and keyboard and another on the screen. d3648x12e12j\f1bi5I For example, here is a class browser for a set of everyday commodities. From the lattice drawn in the Browser window, we can see that (point at each item with the cursor using the small hand browser) a Tomato is a Vegetable, and also a FragileCommodity. A Vegetable is a Grocery, and also a PerishableCommodity. Similarly, Apple can be seen to be a Fruit which is also a Grocery.d3648x12e12j\135f1 1b65f0B2i6I6i9I13i16I5i9I6i7I13i19I13i5I21i6I By pointing at a class in the browser, we can ask Loops to print out more information about a class. For example, (click Apple holding down Leftshift) here is a printout of the class Apple. The information in bold font shows information that is defined locally in the class Apple itself. We see that Apple has Fruit as a super class. This corresponds to the visual display in the browser window. Going back to the printout, we can look at the class variables for the class Apple, the descriptions of the instance variables, and the methods. d3648x12e12j\115f1 1b36f0B Apple also inherits information through the class lattice. The nonbold information about Apple shows variables and methods that are inherited from Apples's super classes. (point at pieces of information which is inherited). For example, we see that the variable lifeTime must be inherited.d3648x12e12j\172f1b52B1f0 40i8I (camera shifts back to browser lattice)d3648x12e12j\f1b Going back to the browser, we find out where the pieces come from using the WHEREIS option. Here we see that the instance variable lifetime comes from PerishableCommodity, and quantity (qty) comes from Commodity, and price is defined locally. We also see that the methods SetPrice and Display are defined locally in the class Apple itself. The method TransferOwner comes from Commodity, and SetPrice is defined locally.d3648x12e12j\132i8I12i19I6i8I18i9I62i8I5i7I60i14I12i9I6i8I View: Fade back to Austin sitting at a workstation.d3648x12e12j\f1bi5I Message sending is a central idea in object-oriented programming. This is the way that objects communicate; it corresponds roughly to procedure call in more traditional languages -- one object causes another object to do something by sending it a message. An important difference from procedure call is that the sender of a message need not know the name of the procedure used by the receiver of the message -- the sender only needs to know a selector for the method. This is a key feature behind the idea of protocols. Two different objects can obey the same set of protocols, that is, carry out the same kinds of operations even though their implementations are completely different. For example, an object for displaying text and an object for displaying pictures may both use a display protocol, but have completely different ways of carrying it out. This makes it possible to define uniform interfaces to different classes of objects. d3648x12e12j\788i7I View: Fade back display at workstation.d3648x12e12j\f1bi5I In Loops, a $ comes before Loops names. A left arrow is used for sending a message to an object. (start typing (_ $Apple New 'App1)) For example, to create an instance of a the class Apple, and name it "App1", we send a New message to the class Apple like this:d3648x12e12j\99f1b37f0B87i3I (_ $Apple New 'App1).d3648x12e12j By sending a Display message to App1, (camera moves out to where it can see typing and mouse postion -- which should be on clear area of screen) d3008x12e12j\13i7I17f1 1b106f0B (_ $App1 Display)d3648x12e12j we cause a picture of an apple to appear on the display. (move App1 to position and click down) using the specialized display method of Apples. d3008x12e12j\58f1b38f0B To see the variables of App1 send an Inspect message.d3648x12e12j\37i7I (_ $App1 Inspect)d3648x12e12j This creates an inspector window which shows the instance variables and their values. From this window we can inspect and change these variables directly by selecting them with the mouse. (click mouse Local in title area of inspect window) We have just moved from showing the values for all of the instance variables of App1, including the ones that are inherited to showing only those which are local. The question marks indicate where no values have been set locally yet. (click mouse Local in title area of inspect window) So far, all of the values in the instance App1 are being inherited from the class Apple. d3008x12e12j\190b52B236b52B We can set a value in App1 using the syntaxd3648x12e12j @(app1 price)_90d3648x12e12j Then if we redisplay the inspector, we see that new price, and also the indication that it has been set locally in the instance, although the values of the other variables are still being inherited.d3008x12e12j The next part of the exercise anticipates the data-oriented paradigm of the afternoon lecture. We were told to create a gauge and attach it to the price of App1. This can be done in a single step as follows (click mouse in demo Menu on Monitoring ...):d3648x12e12j\208f1 1b44f0B (_New $VerticalScale Attach $App1 'price)d3648x12e12j and placing the gauge on the screen. Now if we change the price of $App1, asd3008x12e12j (_@ $App1 price 45)d3648x12e12j the gauge immediate shows the change on the display. This also works if we use a program -- say a method to change the price -- as ind3008x12e12j (_ $App1 SetPrice 85)d3648x12e12j View. Fade back to Austin at the terminal. d3648x12e12j\f1bi5I In most programming systems, one would have to incorporate both functions -- price calculation and display updating -- into the same program. In Loops, the active value mechanism separates these functions -- making it possible to attach gauges to variables without changing the programs at all. This makes it easy to "gauge" up a program. d3648x12e12j Gauges are an interesting tool for monitoring the behavior of a program. They are much better than trace statements, which disappear as they scroll off a "glass teletype". Loops comes with a collection of gauges, and new ones are being invented all the time. Part of our afternoon exercises was to implement a new kind of gauge.d3648x12e12j The rest of the first set of exercises was about facilities for editing and debugging programs. These facilities in Loops make extensive use of the Interlisp-D environment on which Loops stands. An example of this is the integration with the Loops Break Package -- an interactive facility for debugging programs. Loops extends the Break Package to work with objects. d3648x12e12j For example, suppose that I am working on a large program, possibly with parts of it written by other people. Suppose also that some unidentified part of the program is clobbering the value of some variable -- such as the price of App1. Using the Loops extension of the Break Package, we can ask the system to Break -- that is, stop -- whenever any program tries to change that variable. Like this: ...d3648x12e12j\347i3I View. Fade back to the display terminal. d3648x12e12j\f1bi5I I can ask the system to Break when the price of Apple1 is changed as followsd3648x12e12j (BreakIt $App1 'price)d3648x12e12j Now if we invoke the SetPrice method as before ...d3008x12e12j (_ $App1 SetPrice 25)d3648x12e12j a Break Window appears on the screen (camera has panned over to midscreen where the break window has come up). This window shows that a program is trying to change the value of the price of Apple1 from 85 to 25. By selecting the BT option, we can get a back trace of the calling stack. Here we see that the PutValue was called from inside Apple.SetPrice. We can look at the calling arguments by selecting the item in the stack like this -- and we can inspect those arguments (which may be objects like apple1) like this.d3008x12e12j\36f1 2b71f0B201i8I These debugging features enable us to to find the spot in the program that is attempting to set the price. To resume the computation, we can just select the OK option, and the Break window will go away, the computation will procede, and the gauge on the screen will be updated.d3648x12e12j Time 13:00x12e12\f1b10f5B View: Hallway. Austin near the classroom door.d3648x12e12j\f1bi5I Script for Austin: d3648x12e12j\f1bi18I Data-oriented programming was the main subject for the afternoon lecture. d3648x12e12j Time 13:20x12e12\f1b10f5B Special Effects: Fade to Loops Color Saturn Logo with subtitle as follows:d3648x12e12j\f1bi16I d3648x12e12j\u58U Lecture 2d3648x12e12c Data-oriented Programmingd3648x12e12c d3648x12e12j\u58U Film Clip: 03-00-34 to 03-01-06. DGB. Welcome back.d3648x12e12j\i10I2b8B4b9f1B21f0 Special Effects: Subtitle appears for a few seconds.d3648x12e12j\f1bi16I d3648x12e12j\u58U Daniel G. Bobrowd3648x12e12c Knowledge Systems Aread3648x12e12c Xerox PARCd3648x12e12c d3648x12e12j\u58U d3648x12e12j Film Clip: 03-03-24 to 03-04-22. Dual of object-oriented pgming.d3648x12e12j\i10I2b8B4b9B2f1 31f0 Film Clip: 03-14-27 to 03-14-50. One mechanism, many applications.d3648x12e12j\i10I2b8B4b9f1B35f0 Film Clip: 03-17-04 to 03-18-30. Nesting.d3648x12e12j\i10I2b8B4b9B2f1 8f0 Film Clip: 03-19-26 to 03-19-49. In KRL, ....d3648x12e12j\i10I2b8B4b9B2f1 12f0 Film Clip: 03-27-08 to 03-28-20. Arbitrary msgs.d3648x12e12j\i10I2b8B4b9B2f1 15f0 Film Clip: 03-35-16 to 03-37-23. Gauges.d3648x12e12j\i10I2b8B4b9B2f1 7f0 Film Clip: 04-03-32 to 04-03-47. Thank you.d3648x12e12j\i10I2b8B4b9B2f1 10f0 Time 19:30x12e12\f1b10f5B View: Camera on Austin seated at workstation, ready to work on exercises.d3648x12e12j\f1bi5I The next set of exercises was about defining and specializing classes. The examples for these exercises were drawn from the Loops gauges.d3648x12e12j The first exercise was to make an accumulating gauge, that is, a gauge that indicates the arithmetic sum of all of the values that have been set so far.d3648x12e12j View: Workstation screen.d3648x12e12j\f1bi5I The course material suggests that we create a class for Accumulator by specializing the class LCD. We begin by creating a class browser for the gauges.d3648x12e12j (Browse GAUGESCLASSES)d3648x12e12j Using the Browser -- we can use the Specialize option, and type in the name of the new class. Note that the new Accumulator class now appears in the browser window.d3648x12e12j View: Zoom in on Browser window for gauges.d3648x12e12j\f1bi5I We can take a look at the Accumulator class. After selecting the PrintSummary option, we see that Accumulator has several methods. The exercise instructions suggest that we specialize the Set method -- listed here. To look at that method, we can use the EM option to examine the method function from the lisp editor.d3648x12e12j\190i3I We wait for a moment while Lisp fetches the source code from a file server, and now we see that the method for Set takes two arguments -- self, the instance of the accumulator class -- and the new reading. To define a new Set message for Accumulator, we typed3648x12e12j DM (Accumulator d3648x12e12j -- let's see, what arguments does DM take? We can use ?= facility to find out. -- d3008x12e12j DM( Accumulator ?=d3648x12e12j -- ah -- we just need to name the selector and arguments. Of course. We're defining a method for Set. -- sod3008x12e12j DM (Accumulator Set (self reading) )d3648x12e12j So now we're in the Interlisp editor again. We should put in a comment ---d3008x12e12j (* Method for accumulating readings in order to Set an Accumulator.)d3648x12e12j -- And we want to just specialize the code for the LCD by adding the new reading to the existing reading in the Accumulator. We can use SendSuper to activate the inherited code for Set. So all we need to do is to add the new reading. Like this: d3008x12e12j (_Super self Set (IPLUS reading @reading]d3648x12e12j -- and make sure that the method returns that reading as its value.d3008x12e12j Austin deletes the self Lisp variable at the end of the Method.d3648x12e12j\f1 63f0 and we can exit the Editor.d3008x12e12j Now let's build an accumulator, and test it out. First we create an instance of the Accumulator class and save it in the Lisp variable ac1.d3648x12e12j (SETQ ac1 (_ $Accumulator New)) d3648x12e12j Then the exercise instructions say to set the scale and tell the Accumulator to Update. Okay --d3648x12e12j (_ ac1 SetScale 0 100) (_ ac1 Update)l3648x12e12j -- Ah -- now the picture of the Accumulator-LCD appears on the screen. So we can send it Set messages. We'll set it to ten.d3648x12e12j (_ ac1 Set 10)d3648x12e12j We'll try it again and again. d3648x12e12j redo redo redol3648x12e12j It's accumulating! It works! d3648x12e12j View: Austin in office.d3648x12e12j\f1bi5I Script for Austin: d3648x12e12j\f1bi18I There were several more parts to the exercise -- each part more challenging and requiring more initiative than the previous. The last part of the exercise was about creating new classes by combining existing classes. Several of the gauges that come with Loops are made in this way -- by combining parts of simpler gauges. d3648x12e12j View: Workstation display view. d3648x12e12j\f1bi5I27f0 Special effect: WIPE!!! d3648x12e12j\f1bi16I For example, the DigiMeter is made by combining a Meter with an LCD and the DigiScale is made by combining a HorizontalScale with an LCD. The last problem was to define a DigiDial, by combining a Dial with an LCD. I was surprised. Along with almost everybody else in the class, we were actually able to do this. In most programming languages this would be a very difficult thing to do. Even in object-oriented systems lacking a multiple inheritance capability, this would be hard . In Loops it was easy. Facilities for combining classes are an important part of Loops.d3008x12e12j\17i9I50i9I87bi8BI253b20B View: Camera focuses on Austin in the hallway. d3648x12e12j\f1bi5I42f0 At this point in the course, we all had had a pretty intensive first day. We had learned a lot about object-oriented programming and data-oriented programming, and had all become acquainted with the user interface in Loops. The last session of the day was to introduce the Truckin game.d3648x12e12j\276i7I We hadn't heard much about Truckin yet. We all knew that it was part of a scheme to teach us to build a small expert system, but we didn't really know how that was going to work. This lecture was to be a brief introduction, so we could think about the ideas over night.d3648x12e12j\27i7I Time xx:xxx12e12\f1b10f5B Special Effects: Fade to Loops Color Saturn Logo with subtitle as follows:d3648x12e12j\f1bi16I d3648x12e12j\u58U Lecture 3d3648x12e12c Introduction to Truckind3648x12e12c\16i7I d3648x12e12j\u58U Film Clip: 05-02-51 to 05-05-25. Sanjay -- introductory fragments.d3648x12e12j\i10I2b8B4b9f1B35f0 Special Effects: Subtitle appears for a few seconds.d3648x12e12j\f1bi16I d3648x12e12j\u58U Sanjay Mittald3648x12e12c Knowledge Systems Aread3648x12e12c Xerox PARCd3648x12e12c d3648x12e12j\u58U Time xx:xxx12e12\f1b10f5B View: Sanjay in front of Truckin printout. Wearing same clothing as on the previously-recorded video tape. Sanjay will be pointing at the game board. d3648x12e12j\f1bi4I22i7I Script for Sanjay.d3648x12e12j\f1b Teaching about expert systems is usually quite time-consuming. In order to study an example expert system, the first several weeks are usually spent learning the vocabulary and concepts of the domain -- be it medical diagnosis, experiment planning, or whatever.d3648x12e12j However, this course on knowledge programming in Loops is only three days long. To give you experience with an expert system, we had to find a problem area that you already know about -- something from common experience.d3648x12e12j The domain we picked is about planning a truck route -- buying and selling goods to make a profit. Buying goods and going places is something that we all know something about.d3648x12e12j Truckin is a simulation world for this domain. It comes to life as a sort of video game, except that it is not played by people. Behind each truck is a small expert system, that makes the decisions about where to go, and what to buy and sell. d3648x12e12j\i7I124b112B Your job, starting tomorrow afternoon, is to build an automated player. Your player will act as an independent trucker, trying to make a profit in the simulation worldd3648x12e12j\54i16I30bi19BI This is a game board for the Truckin game. This is a highway, this is a road stop, this is a truck going down the highway. d3648x12e12j\29i7I Truckin provides an interactive environment in Loops for developing your player. Trucks go back and forth. They take turns running. They buy and sell.d3008x12e12j\i7I Road stops with the icons are called producers. Trucks can buy goods there. Roadstops with a commodity name -- like groceries -- are consumers. Trucks can sell goods there. Some Roadstops sell gas; some levy taxes -- like the weigh stations, some correspond to rough spots in the road. If a truck goes too fast over a rough road it may damage some fragile cargo.d3008x12e12j\37i9I89i9I A pedagogical goal in the design of Truckin is that the simulation is intended to be complex enough to preclude trivial solutions -- such as linear programming solutions. It is meant to be like the kinds of domains in which expert systems are usually applied -- messy real-world problems that need expertise, not just mathematical formulas.d3648x12e12j\36i7I Film Clip: 05-12-48 to 05-13-35. SM: An assortment of trucks.d3648x12e12j\i10I2b8B4b9f1B30f0 Film Clip: 05-15-55 to 05-16-58. SM: Bandits, conflicting constraintsd3648x12e12j\i10I2b8B4b9f1B38f0i Film Clip: 05-17-28 to 05-18-00. SM: Austin question.d3648x12e12j\i10I2b8B4b9f1B22f0 Film Clip: 05-19-08 to 05-20-40. SM: Starting with Peddler.d3648x12e12j\i10I2b8B4b9f1B28f0 Film Clip: 05-24-17 to 05-24-47. SM: What can you do in a move?d3648x12e12j\i10I2b8B4b9f1B32f0 Film Clip: 05-27-09 to 05-28-04. SM: Gauges.d3648x12e12j\i10I2b8B4b9f1B13f0 Time xx:xxx12e12\f1b10f5B View: Display screen showing collection of Loops Gauges all counting down from 5 to 0. Ticking sound in background ala 60 minutes. d3648x12e12j\f1bi4I Time xx:xxx12e12\f1b10f5B Special effects: A white title on a blue background.d3648x12e12j\f1bi15I d3648x12e12j\u58U Knowledge Programming in Loops:d3648x12e12c\b Second Day of the Experimental Coursed3648x12e12c\b d3648x12e12j\u58U Time xx:xxd3648x12e12j\f1b10f5B Camera focuses on Austin in the hallway. d3648x12e12j\f1b42f0 Script for Austin.d3648x12e12j\f1bi On the first day, several people worked until late in the evening just to get ahead in the exercises of the course. Others went home to read the manuals. Pretty much everybody had started thinking about Truckin -- proposing strategies that they wanted to build into their expert systems.d3648x12e12j\205i7I The first item on the agenda for the second day was a lecture on rule-oriented programming. I was curious about rules, because although everybody in AI has heard a lot about using rules, rule languages have not been widely accepted or available. I had never built a big program using rules, and I expected to learn something about how to do this. Also, we had been told that rules would be an important part of the mini-expert systems that we would be building for Truckin.d3648x12e12j\468i7I Time 03:10x12e12\f1b10f5B Special Effects: Fade to Loops Color Saturn Logo with subtitle as follows:d3648x12e12j\f1bi16I d3648x12e12j\u58U Lecture 4d3648x12e12c Rule-oriented Programmingd3648x12e12c d3648x12e12j\u58U Film Clip: 06-03-28 to 06-05-49. MJS. What's special about rules.d3648x12e12j\i10I2b8B4b9B2f1 33f0 Special Effects: Subtitle appears for a few seconds.d3648x12e12j\f1bi16I d3648x12e12j\u58U Mark Stefikd3648x12e12c Knowledge Systems Aread3648x12e12c Xerox PARCd3648x12e12c d3648x12e12j\u58U Film Clip: 06-09-10 to 06-11-54. MJS. Wash Machine, 1-shots.d3648x12e12j\i10I2b8B4b9B2f1 28f0 Film Clip: 06-17-36 to 06-19-09. MJS. Explanation ...d3648x12e12j\i10I2b8B4b9B2f1 21f0 Film Clip: 06-20-37 to 06-21-55. MJS. Austin .. how auditing works.d3648x12e12j\i10I2b8B4b9B2f1 35f0 Film Clip: 06-34-21 to 06-36-00. MJS. Peddler ...d3648x12e12j\i10I2b8B4b9B2f1 17f0 Film Clip: 06-54-02 to 06-55-34. MJS. In the exercises.d3648x12e12j\i10I2b8B4b9B2f1 23f0 Time 07:00x12e12\f1b10f5B View: Fade to Austin sitting at a workstation. A course notebook is at hand, open to the pages of the first set of exercises. Interlisp-D manuals are also at hand.d3648x12e12j\f1bi5I The workstation screen shows the standard set-up for Truckin. Second camera is on the screen (or a slave screen).d3648x12e12j\f1b53i7I Set Up. Truckin should be initialized, and the Traveler player should be compiled with auditing turned on except for FindStoppingPlace. Truckin is running, but has been interrupted by a CNTRL-SHIFT break. d3648x12e12j\f1b9i7I32i8I82i7I Script for Austin.d3648x12e12j\f1bi18I The next set of exercises emphasized debugging in rules. We started with an existing player called Traveler. d3648x12e12j\100i8I View. Fade to second camera on a slave screen. The workstation screen shows the standard set-up for the Loops Demo. Perhaps a split-screen with one camera on the mouse and keyboard and another on the screen - SmallTalk style. d3648x12e12j\f1bi5I A convenient way to access the rules of a player is through a browser. So ...d3648x12e12j (Browse $Player)d3648x12e12j Here is the Traveler. By selecting the EM option, we can edit one of the methods -- which happens to be implemented as a Loops RuleSet. Now the rules appear on the screen. We will edit the rules in the Traveler that are used to determine a stoppingPlace -- that is, a RoadStop on the route to a final destination. So here are the rules. The instructions say that we should turn on auditing -- that is, the saving of dependency trail -- so we change the compiler options for auditing.d3648x12e12j\12i8I186i8I30i13I Compiler Options: A;d3648x12e12j One of the first things that we did was to practise using the dependency trail mechanism for debugging. So we can type OK to start Truckin going again, and we see the various trucks running. The gauges at the right hand side have been attached to monitor fuel consumption, and the weight of cargo, and such things. d3648x12e12j\132i7I Pause for 5 seconds or so to let people watch and understand the game in action.d3648x12e12j\f1 80f0 Now my truck is going, and I'll interrupt it with the Rule Exec by typing a CTRL-F. That new window is the Rule Exec. I can get the value of variable by typing its name. So, for exampled3648x12e12j re: stoppingPlaced3648x12e12j\4b13B That tells me the next place that my player has decided to stop. To see what rule was behind that decision, I type can ask "why" as follows:d3008x12e12j re: why stoppingPlaced3648x12e12j\4b17B and now the text of the rule comes up. If we type OK, to the Rule Exec, the simulation just continues. Another debugging technique is to attach additional gauges to things. So to attach a gauge to my stoppingPlace, I could interrupt Truckin again. (Use CTRL-SHIFT.) For example, we can attach an LCD to the stoppingPlace of my trucker as follows:d3008x12e12j\236i8I8f1 17f0 43i13I (_New $LCD Attach $Austin 'stoppingPlace)d3648x12e12j and we can place gauge next to the other ones. Now when we run Truckin some more, we see that the new gauge shows the changes to my trucker's stoppingPlace as they are computed. d3008x12e12j\64i7I72i13I Another technique is stepping through the rules. To do this, we stop Truckin again (Use CTRL-SHIFT) and change the compiler options. We go up to the class browser for Players, and edit the method for FindStoppingPlace. Now we change the compiler options d3648x12e12j\70i7I7f1 16f0 Compiler Options: BT PR;d3648x12e12j Now we type OK to start Truckin again, and ah. Now the my RuleSet has started running. We can see a printout of the rule in the top window. In the Rule Exec, I can now ask any question as before. To go to the next rule, I just type OK. And the next rule appears. This technique can be useful in determining why a particular rule does not fire in a RuleSet.d3648x12e12j\24i7I View: Fade to Austin sitting at a workstation. A course notebook is at hand, open to the pages of the first set of exercises. Interlisp-D manuals are also at hand.d3648x12e12j\f1bi5I The last part of this exercise was to specialize the Traveler to create a new player, with slightly altered structure and behavior. At the end of this exercise, we knew enough about rules to start expressing our own strategy ideas in a personalized Truckin player. d3648x12e12j\53i8I189i7I Next we had a lecture about the Truckin knowledge base and simulation. d3648x12e12j\32i7I Time 03:10x12e12\f1b10f5B Special Effects: Fade to Loops Color Saturn Logo with subtitle as follows:d3648x12e12j\f1bi16I d3648x12e12j\u58U Lecture 5d3648x12e12c The Truckin Knowledge Based3648x12e12c\4i7I d3648x12e12j\u58U Film Clip: 07-06-20 to 07-07-35. SM. Truckin RoadMapd3648x12e12j\i10I2b8B4b9B1f1 19f0 Special Effects: Subtitle appears for a few seconds.d3648x12e12j\f1bi16I d3648x12e12j\u58U Sanjay Mittald3648x12e12c Knowledge Systems Aread3648x12e12c Xerox PARCd3648x12e12c d3648x12e12j\u58U Film Clip: 07-08-02 to 07-08-28. SM. Cheating ...d3648x12e12j\i10I2b8B4b9B2f1 17f0 Film Clip: 07-13-04 to 07-14-35. SM. Austin on browsers.d3648x12e12j\i10I2b8B4b9B2f1 24f0 Film Clip: 07-08-02 to 07-08-28. SM. Cheating ...d3648x12e12j\i10I2b8B4b9B2f1 17f0 Film Clip: 07-30-27 to 07-31-49. SM. 3 msgs to gameMaster.d3648x12e12j\i10I2b8B4b9B2f1 26f0 Film Clip: 08-00-32 to 08-01-00. SM. One more hint. Crowd leaving.d3648x12e12j\i10I2b8B4b9B2f1 35f0 View: Austin sitting at a workstation. A course notebook is at hand, open to the pages of the first set of exercises. Interlisp-D manuals are also at hand.d3648x12e12j\f1bi5I The workstation screen shows the standard set-up for Truckin. Second camera is on the screen (or a slave screen).d3648x12e12j\f1b53i7I Script for Austin.d3648x12e12j\f1bi18I We worked for the rest of the afternoon on our independent truckers. People discussed strategy and even shared rules. Some people worked late into the evening, others came early in the morning. Just before lunch we had a lecture on advanced features. d3648x12e12j\47i21I Special effects: Show sequence of slides from 1st course, of people working on their players, puzzling at their workstations. Maybe with music background.d3648x12e12j\f1bi15I View: Display screen showing collection of Loops Gauges all counting down from 5 to 0. Ticking sound in background ala 60 minutes. d3648x12e12j\f1bi4I Special effects: A white title on a blue background.d3648x12e12j\f1bi15I d3648x12e12j\u58U Knowledge Programming in Loops:d3648x12e12c\b Third Day of the Experimental Coursed3648x12e12c\b d3648x12e12j\u58U Special effects: Show more of the sequence of slides from 1st course, of people working on their players, puzzling at their workstations. Maybe with music background.d3648x12e12j\f1bi15I Time 03:10x12e12\f1b10f5B Special Effects: Fade to Loops Color Saturn Logo with subtitle as follows:d3648x12e12j\f1bi16I d3648x12e12j\u58U Lecture 6d3648x12e12c Advanced Featuresd3648x12e12c d3648x12e12j\u58U Film Clip: 08-01-13 to 08-01-50. DGB. This lecture has the property ...d3648x12e12j\i10I2b8B4b9B2f1 39f0 Special Effects: Subtitle appears for a few seconds.d3648x12e12j\f1bi16I d3648x12e12j\u58U Mark Stefikd3648x12e12c Knowledge Systems Aread3648x12e12c Xerox PARCd3648x12e12c d3648x12e12j\u58U Film Clip: 08-02-41 to 08-03-44. MJS. Advanced features means ...d3648x12e12j\i10I2b8B4b9B2f1 33f0 Film Clip: 08-16-41 to 08-17-27 MJS. Composite Objects.d3648x12e12j\i10I2b8B4b8B2f1 24f0 Film Clip: 08-23-52 to 08-24-50 MJS. Perspectives.d3648x12e12j\i10I2b8B4b8B2f1 19f0 Film Clip: 08-27-50 to 08-30-15 MJS. Mixins vs. perspectives.d3648x12e12j\i10I2b8B4b8B2f1 30f0 Film Clip: 08-33-00 to 08-33-31 MJS. Knowledge bases.d3648x12e12j\i10I2b8B4b8B2f1 22f0 d3648x12e12j\f5b View: Austin in lounge area.d3648x12e12j\f1bi7I Script for Austin.d3648x12e12j\f1bi18I During an afternoon break, Sanjay Mittal gave us a demo of the Loops tester. We learned that the tester is an expert system, written in Loops, used to certify new releases of Loops.d3648x12e12j Special Effects: Fade to Loops Color Saturn Logo with subtitle as follows:d3648x12e12j\f1bi16I d3648x12e12j\u58U Demod3648x12e12c The Loops Testerd3648x12e12c d3648x12e12j\u58U Special Effects: Subtitle appears for a few seconds.d3648x12e12j\f1bi16I d3648x12e12j\u58U Sanjay Mittald3648x12e12c Knowledge Systems Aread3648x12e12c Xerox PARCd3648x12e12c d3648x12e12j\u58U View: Sanjay seated at workstation. (Second camera is set-up on computer screen).d3648x12e12j\f1bi7I Script for Sanjay.d3648x12e12j\f1bi18I Until last fall, we had no systemmatic way of certifying new releases of Loops. Whenever someone on the Loops development team changed the system, he was responsible for verifying that the code worked before putting it into a new release. However, Loops had grown to about three hundred thousand bytes of source code, and sometimes changes to one part of the system had unexpected interactions with another part of the system.d3648x12e12j Last fall I started building an expert system that would automatically, and systemmatically put Loops through its paces. It was an expert system about Loops itself, designed to uncover bugs in new releases. Metaphorically, it harnesses Loops specifications -- that is, a knowledge base about what Loops is supposed to do -- to a tireless computer. Now the Loops development team does not have to depend only on its human resources -- three people -- to spot bugs in a new release of Loops. We could call on the services of an expert system to check things out.d3648x12e12j\238i20I Here is an example of the tester in action:d3648x12e12j View: Switch to camera on Workstation display.d3648x12e12j\f1bi7I In Loops, like any system that is built in layers, the more sophisticated features depend on the correctness of the lower level features. Similarly, the tester must first certify the most primitive features of Loops, and then go on to the higher level features.d3648x12e12j On the screen the tester has brought up a browser to show the relationships between the tests in its knowledge base. In contrast with a class browser, the lines in the tester browser show dependencies between subtests. The tests on the right depend on the ones in the left.d3648x12e12j The current set of tests covers most of Loops functionality, and all of the low level operations -- such as message sending, value putting and getting for various cases. The tester provides a framework for defining new tests. Using this framework, the tests are entered manually. Let's take a look at one of the tests in the knowledge base.d3648x12e12j If we just want to display a test without making any changes, we select the PP option on the middle-button menu for the selected test. However, by selecting the EditTEST option in the left-button menu, we enter a mode where the tests can be created, edited, including the manipulation of various links between tests.d3648x12e12j\76bi2BI83bi8BI Now we're ready to run the tester. If we select the AllTests option in the menu, the tester starts. As a test is started, its name is outlined in the browser and a message appears in the typescript window. When a test completes correctly, it is blackened.d3648x12e12j\53b8B This mode of running the tester steps through the entire knowledge base without user interaction -- unless there is an error. Interactive modes of running specific tests are also available -- for situations where bugs have been discovered. d3648x12e12j View: Austin in lounge area.d3648x12e12j\f1bi7I Script for Austin.d3648x12e12j\f1bi18I Suddenly it was mid afternoon of the last day and time for the knowledge competition. People were quickly putting the finishing touches on their players -- adding that one last rule, saving their knowledge bases.d3648x12e12j Before the competition actually started, people were asked to explain the ideas behind their expert systems. d3648x12e12j Special Effects: Fade to Loops Color Saturn Logo with subtitle as follows:d3648x12e12j\f1bi16I d3648x12e12j\u58U The Knowledge Competitiond3648x12e12c d3648x12e12j\u58U Note: Tapes 9 & 11 are people shots. Tapes 10 & 12 are Truckin display:d3648x12e12j\f1bi5I52i7I Film Clip: 09-00-53 to 09-01-30. Steve Gadol.d3648x12e12j\i10I2b8B4b9B2f1 12f0 Film Clip: 09-02-27 to 09-03-00. Chris Tong.d3648x12e12j\i10I2b8B4b9B2f1 11f0 Film Clip: 09-04-16 to 09-05-15 Martin Kay.d3648x12e12j\i10I2b8B4b8B2f1 11f0 Film Clip: 09-10-06 to 09-11-50. Lee Erman and Steve Reis.d3648x12e12j\i10I2b8B4b9B2f1 25f0 Film Clip: 09-12-56 to 09-13-02 SM: Here's the gameboard.d3648x12e12j\i10I2b8B4b8B2f1 25f0 Film Clip: 09-21-39 to 09-22-04 MJS: Do we run a Peddler?d3648x12e12j\i10I2b8B4b8B2f1 25f0 Film Clip: 09-10-06 to 09-11-50. Lee Erman and Steve Reis.d3648x12e12j\i10I2b8B4b9B2f1 25f0 Film Clip: 09-12-56 to 09-13-02 SM: Here's the gameboard.d3648x12e12j\i10I2b8B4b8B2f1 25f0 ****d3648x12e12j\f1b Film Clip: 10-12-09 to 10-12-52 SM: Here's the game board!d3648x12e12j\i10I2b8B4b8B2f1 26f0 Film Clip: 10-16-47 to 10-17-08. Gauges for Gadol.d3648x12e12j\i10I2b8B4b9B2f1 17f0 Film Clip: 10-22-56 to 09-23-00 Game starts.d3648x12e12j\i10I2b8B4b8B2f1 12f0 Film Clip: 10-28-42 to 10-29-05 Sell that gold!d3648x12e12j\i10I2b8B4b8B2f1 15f0 ****d3648x12e12j\f1b Film Clip: 09-42-01 to 09-42-22. We're going back to get gas.d3648x12e12j\i10I2b8B4b9B2f1 28f0 Film Clip: 11-06-37 to 11-06-51. Luey got robbed. Go Tek!d3648x12e12j\i10I2b8B4b9B2f1 25f0 ****d3648x12e12j\f1b Film Clip: 12-02-56 to 12-04-09. SM: To summarize ... tomatoes.d3648x12e12j\i10I2b8B4b9B2f1 30f0 Film Clip: 12-04-50 to 12-05-15. Getting into endgame!d3648x12e12j\i10I2b8B4b9B2f1 21f0 ****d3648x12e12j\f1b Film Clip: 11-08-04 to 11-08-43 Mav broke. last ditch strategy.d3648x12e12j\i10I2b8B4b8B2f1 33f0 Film Clip: 12-10-04 to 12-10-43 Very end.d3648x12e12j\i10I2b8B4b8B2f1 9f0 Film Clip: 11-10-04 to 11-10-28 Let's hear it for the turtle!d3648x12e12j\i10I2b8B4b8B2f1 29f0 View: Austin in hallway.d3648x12e12j\f1bi7I Script for Austin.d3648x12e12j\f1bi18I After the knowledge competition, we gathered for a wrap-up session.d3648x12e12j Special Effects: Fade to Loops Color Saturn Logo with subtitle as follows:d3648x12e12j\f1bi16I d3648x12e12j\u58U Lecture 7d3648x12e12c Wrap-Upd3648x12e12c d3648x12e12j\u58U Film Clip: 13-02-21 to 13-02-52. DGB. The coin we are paid in ...d3648x12e12j\i10I2b8B4b9B2f1 33f0 Special Effects: Subtitle appears for a few seconds.d3648x12e12j\f1bi16I d3648x12e12j\u58U Daniel G. Bobrowd3648x12e12c Knowledge Systems Aread3648x12e12c Xerox PARCd3648x12e12c d3648x12e12j\u58U Film Clip: 13-06-59 to 13-07-35 DGB. Outline of topics. d3648x12e12j\i10I2b8B4b8B2f1 25f0 Film Clip: 13-15-00 to 13-15-22 Ideas and feedback.d3648x12e12j\i10I2b8B4b8B2f1 19f0 Film Clip: 13-17-26 to 13-17-34 How do you know when to use ...d3648x12e12j\i10I2b8B4b8B2f1 31f0 Film Clip: 13-21-01 to 13-21-27 Objects.d3648x12e12j\i10I2b8B4b8B2f1 8f0 Film Clip: 13-23-05 to 13-23-35 Rules.d3648x12e12j\i10I2b8B4b8B2f1 6f0 Film Clip: 13-26-50 to 13-28-20 Combination methods for ...d3648x12e12j\i10I2b8B4b8B2f1 27f0 Film Clip: 13-33-57 to 13-34-10 Demons - Erman, MJS, DGB.d3648x12e12j\i10I2b8B4b8B2f1 25f0 Film Clip: 13-50-00 to 13-51-43 Research objectives ...d3648x12e12j\i10I2b8B4b8B2f1 23f0 Film Clip: 13-52-00 to 13-52-37 Thank you very much!d3648x12e12j\i10I2b8B4b8B2f1 20f0 View: A sequence of stills selected from the video tape, with a 3-second pause between each:d3648x12e12j\f1bi Still Shot: Mark doing introduction.d3648x12e12j\i11I2f1 24f0 Still Shot: Danny at lecture.d3648x12e12j\i11I2f1 17f0 Still Shot: Austin beckoning at workstation.d3648x12e12j\i11I2f1 32f0 Still Shot: Sanjay at lecture.d3648x12e12j\i11I2f1 18f0 Still Shot: Crowd scene from the knowledge competition.d3648x12e12j\i11I2f1 43f0 Special Effect: Starts with a still shot of the Truckin gameboard with a truck about to pull into Alice's Restaurant. This shot becomes animated as a game truck (labeled Xerox) is shown slowing down to park. Fades to a scene filmed in "registration" of a REAL Xerox truck, pulling into a parking place. The doors open, and Danny and Sanjay start running into a building, with Mark racing along behind. Camera pans upward and it is the REAL Alice's Restaurant in La Honda! Picture freezes and the following credits overlay on the screen or scroll up from below:d3648x12e12j\f1bi56I1i d3648x12e12j\u58U Slide:d3648x12e12j\b Script Engineer: Mark Stefikl4269d4918x12e12j\b Production Engineer: Ken Beckmanl4269d4918x12e12j\b Music Engineer: Blue Jeansl4269d4918x12e12j\b Knowledge Engineer: Lynn Conwayl4269d4918x12e12j\b Loops Course Engineers: Mark Stefik, Daniel Bobrow, and Sanjay Mittall4269d4918x12e12j\b d3648x12e12j\u58U View: White letters on a blue background.d3648x12e12j\f1b42f0B d3648x12e12j\u58U The experimental course "Knowledge Programming in Loops" is offered periodically by the Knowledge Systems Area at Xerox PARC. d3648x12e12j\88i22I The Loops Knowledge Programming System is currently available to selected Xerox customers that have been designated as Loops beta-test sites.d3648x12e12j\125i9I d3648x12e12j\u58U d3648x12e12j\b3B THE ENDd3648x12e12c\f9 d3648x12e12j\f9