nan LIBRARY OF THE UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN 510. &4 cop * 2 Digitized by the Internet Archive in 2013 http://archive.org/details/platolessononinf615ches UIUCDCS-R-7If-6l5 /Sl4u44t A PLATO LESSON ON INFORMATION STRUCTURES by Michel Jean Chesnel January, 197^ DEPARTMENT OF COMPUTER SCIENCE UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN URBANA, ILLINOIS JHE LIBRARY OF THE FEB 1 5 1974 tINIVERSllY OH ILLINOIS UIUCDCS-R-71+-615 A PLATO LESSON ON INFORMATION STRUCTURES by Michel Jean Chesnel January, 197^ Department of Computer Science University of Illinois at Urbana-Champaign Urbana, Illinois 61801 This work was supported in part by the Department of Computer Science, University of Illinois at Urbana-Champaign, and was submitted in partial fulfillment for the Master of Science degree in Computer Science, 197^. Ill ACKNOWLEDGMENT The author wishes to express special gratitude to his thesis advisor Professor Edward M. Reingold for his supervision and helpful discussions during the research for this thesis. Special thanks also goes to Professor Marshall Mickunas, Alan Davis, and Ervin Wilson whose students cooperated in making valuable comments. The helpful work of Ms. Lynn Waverly and Ms. Sharon Phillips in preparing this manuscript is gratefully acknowledged. Finally, I give my thanks to my parents, for their support and continuous faith in me, without which I know I could not have even started this thesis. IV TABLE OF CONTENTS Page 1. INTRODUCTION 1 1.1 Nature of the Problem 1 1.2 Computer-Based Education 1 1.2.1 Drill and Practice 3 1.2.2 Tutorial Teaching Mode 4 1.2.3 Inquiry Teaching Mode 5 .1.3 The PLATO IV System 5 2. DEFINITION OF A STRATEGY 7 2.1 Four Basic Principles 7 2.2 Frame Contents and Presentation 8 2.3 Choice of a Mode 9 2.4 Branching 11 3. THE LESSON 12 3.1 Purpose and Scope 12 3.2 Description 12 4. EVALUATION OF THE LESSON 15 4.1 Choice of the Students 15 4.2 Procedure 16 4.3 Students' Comments 17 4.4 Conclusion 19 LIST OF REFERENCES 20 APPENDIX 21 1. INTRODUCTION 1. 1 Nature of the Problem The purpose of the study was to write a lesson in the TUTOR language for the PLATO IV computer assisted instruction system of the University of Illinois. The lesson STR1 written by the author deals with information structures and will be one of the PLATO lessons for the introductory computer science courses. To provide background, a brief description of computer assisted instruction is given, followed by a description of the PLATO IV system. 1. 2 Computer-Based Education Computer-based education is a flexible approach to edu- cational problems. The traditional approach, i.e., the teacher and printing press, made mass education possible. Nowadays, with the greater need of mass and individualized education, another approach is necessary. Computer-based education could be the answer to this problem. For more than a decade now numerous efforts have been made to use computer technology to get a highly individualized education. Various computer-based education systems are in use throughout the United States, 85 such systems are listed in Helen A. Lekan ' s Index to Computer Assisted Instruction (1970). 2 The main characteristic of a computer assisted instruc- tion system is, of course, the use of a computer. This com- puter provides two significant capabilities: memory and logic. The memory feature is also provided by other teaching aids, such as books, films, and tapes, but no aid provides the memory of students ' responses in a form which is directly use- ful for automatic processing. Furthermore, only computer as- sisted instruction takes care of the communication problem on an individualized basis; only computer assisted instruction is adaptative and these last characteristics exist because of the powerful logic of the computer used in each computer assisted instruction system. Any computer assisted instruction system can be divided into two main parts: the hardware and the software. The com- puter is only one component of the hardware, generally the less visible to the student. Each student interacts with the com- puter via a console. An interface is generally needed between the computer and the consoles. A console typically consists of a graphic display device, such as a television monitor display, a C.R.T. or a plasma display panel, and a keyset. The student or the author can read in the computer through the graphic dis- play, and the keyset is used to make requests and responses for the student and to compose and edit lessons for the author. Other devices can be available such as a light pen, an image projector, an audio-tape for playback and recording capability. 3 The software consists of the normal software which is implemented on every computer running in time sharing, so that more than one console can be connected to the computer and operate simultaneously. Each student has the impression that he is the only individual who is interacting with the system. Any computer assisted instruction system must have at least three features: 1) computer assisted instruction must be able to evaluate a student's response by comparing it to various answers predicted by the teacher or author (this eval- uation must occur immediately after the student's answer), 2) computer assisted instruction must provide the teacher or the author with detailed data on student performance, 3) com- puter assisted instruction must make creation and modification of lessons easy for the author. The principal aim of a computer assisted instruction system is to achieve an efficient individualization of instruc- tion. The way of a computer assisted instruction adjusts a learning environment according to students' responses and re- quests can be seen as a "mode." There are three main student modes: drill and practice, the tutorial teaching mode, and the inquiry teaching mode. An ideal computer assisted instruc- tion system would combine all of these student modes. 1.2.1 Drill and Practice Drill and practice consists of presenting to the stu- dent a set of small exercises or problems to solve without 4 having previously shown him the material with which he is supposed to know how to solve these drills. In this mode the student does not learn much new material; he is simply checking how well he knows the material. The computer assisted instruc- tion system prints questions to the student, reads his answer, evaluates its validity, returns appropriate messages, and loads in its memory all the necessary data reflecting the per- formance of the student. In this mode the student is involved rather intensively in the use of the console; nevertheless he needs to know very little about the way the computer assisted instruction system works, since he uses his natural language (English) . 1.2.2 Tutorial Teaching Mode Tutorial teaching is a second mode in which the teacher (or the author) and the computer assisted instruction system take responsibility for the student. This mode was the only one used on computer assisted instruction systems for a long time. It consists of two main parts: a demonstration when the student learns concepts and a supervised practice session when the student has to demonstrate his understanding of the concepts which have been previously presented to him. In this mode the lesson is generally linear so that all the students go through a very similar path. However, "help" and "branch" sequences are provided so that the instruction is adapted to each individ- ual. Since the student has relatively little freedom in this 5 the author must be very familiar with both the language of the computer and the philosophy of teaching. The sequencing in this mode is essential and it is much more complex than frame writing because the problem of sequencing is closely tied to subject matter knowledge and to teaching experience. 1.2.3 Inquiry Teaching Mode The inquiry mode is a third type of computer assisted instruction application. In this mode the student asks ques- tions to the system by using his keyset. Because the student determines himself what he needs and can work entirely at his own rate, the education is really personalized. Another ad- vantage of this mode is that the student needs not know anything about the computer assisted instruction system since communica- tion between the system and the student is again through nat- ural language. The author has to implement routines which locate the required information. If the language of the system is appropriate, this task is not too time-consuming. 1. 3 The PLATO IV System The PLATO IV system (Programmed Logic for Automatic Teaching Operation) uses a high-speed digital computer, a Con- trol Data 6500, as the logic of the whole system. An N.I.U. (Network Interface Unit) is the link between site controllers and the computer. Each site controller can handle up to 32 consoles or terminals. 6 Each terminal is composed of a plasma display panel, a keyboard, a slide projector, a touch panel, an audio device (only few terminal currently have a touch panel and an audio device) . The plasma display contains 512 digitally address- able positions along each axis and has an inherent memory. Thus, once the information is on the screen, no rewriting has to be done as it was the case in the PLATO IV system that used a television display. The computer provides the terminal only with new points to be shown and points to be erased. The ac- tual design of the PLATO IV system makes possible the connec- tion of about 4,000 student terminals within 150 miles of the University of Illinois. The system is running under a special operating system, including time sharing for the 4,000 terminals and files and memory management to handle the huge amount of various data used by all the students and authors. A special teaching- oriented language, TUTOR, has been implemented on the system. Another important feature of the PLATO IV system is the collec- tion of complete record of students' responses and behavior through lessons. 2. DEFINITION OF A STRATEGY Whatever the mode used, there are some common basic principles which apply to lesson writing on a computer assisted instruction system. A survey of these principles will be pre- sented in the following lines. Even before starting to write a lesson, one has to know what sort of students the lesson is intended for. Obviously, if the students are obliged to take the lesson the task of the author will be much more difficult than if the students are "volunteers" and highly motivated. In the latter case, even if the lesson is boring the students will be willing to go through it anyway because the material is at- tractive to them. The same kind of remark will apply if the students are high school students or college students. For each of these cases the same lesson will have to be written differently. Unfortunately, no systematic rule exists and only a highly experienced teacher can really know the different ways of writing a lesson according to the students who are going to take it. 2. 1 Four Basic Principles It is difficult to state specific rules for lesson writ- ing. However, when one has to write a lesson one must respect the four basis principles. 8 First of all is the principle of small steps, which consists of programming a large number of small and easy-to- take steps so that a student can proceed from knowing very lit- tle about a subject to its mastery by going through such a les- son. The second principle is the principle of active respond- ing. The student not only reads explanations and looks at the examples, but also works out some problems and drills. The lesson must use most of the facilities of the computer assisted instruction system to be interactive. The student must have the impression that he has something in front of him with which he can have a "dialog." The third principle is the principle of immediate confirmation. With this principle the student can confirm his answer immediately. The last principle is the principle of self -pacing. Some people naturally learn more rapidly or more slowly than others, and each student will learn better if he can go at his own pace. 2. 2 Frame Contents and Presentation On the PLATO IV system the material is presented to the student on a screen. The contents of such a screen is called the "frame" or "page." Whenever the frame is full the screen is erased and, generally, the next frame or page is displayed. According to the principle of small steps, the frame is composed of small paragraphs and/or graphics. Each paragraph contains an idea or concept. The presentation of each new idea or con- cept is a difficult task for the author. In order to be effi- cient, one must always remember some techniques which make the presentation agreeable to the student and easy to recall too. The text must be easy to understand and without any ambigui- ties. Graphics and drawings must be used as often as possible. Variety is another way to increase the interest of the student and to avoid boredom. The teacher must be aware that the stu- dent cannot remember everything at once/ so whenever it is pos- sible and reasonable, redundancy has to be introduced into the lesson. The meaningfulness of the text is another very impor- tant variable in regard to learning and retention of knowledge, The more meaningful the material is to the student, the easier it is to learn and recall. The readability is also an import- ant variable in regard to learning. There are three main ways to increase readability: 1) use short and easy words, 2) use short sentences, and 3) use as few technical words as possible, Finally, the student must be aware of what he will see, so ex- tensive use of topic heading must show the main points being presented. 2. 3 Choice of a Mode For the lesson STR1 the author has made the assumption that the college students who will go through this lesson can be considered mature and highly motivated. In spite of this assumption, the author has tried to write a lesson which is in- teresting for less motivated students. Based upon this assump- tion that the students are highly motivated, the author has chosen to write the lesson in the inquiry mode which has been described briefly in the first part of this thesis. 10 The lesson contains various topics and for each topic there is a corresponding question or set of questions. The student is free to go through these topics in any order he wants. However, if he does not know anything about the les- son he is advised to follow the "natural" path which is pro- vided. To do so he will have to press the NEXT key at the end of each paragraph and frame, and the lesson will become a linear sequence of topics. Another option is available to the student. He can choose between the three following "modes": 1) text and ques- tions, 2) text only, or 3) questions only. The first mode is useful to the students who go through the lesson for the first time. The second mode is mostly for the students who go through the lesson for the first time, but who do not think it is worth- while to go through questions and drills. The third mode is devoted to the students who already know the material. The flexible structure of the lesson allows the students who are only interested in one or more parts of the lesson to see them without going through all of the other parts. This is precisely a characteristic of the inquiry mode. The students have to know the contents of the lesson or at least to know how to get to a page which contains the con- tents of the lesson. So the structure of the lesson has to be such that the students can know at any time what the main parts of the lesson are. This is done by implementing a table of contents accessible via the TERM key. From this page the 11 students are able to branch to any important part of the lesson by typing the corresponding key(s). Finally, the structure of the lesson must be clear not only to the author but above all to the students. 2. 4 Branching Whatever option the students might choose, the NEXT, BACK, and TERM keys have a special use. By pressing the NEXT key, the student will go to the next paragraph, graphic, or drawing within a frame. At the end of a frame the NEXT key leads the students to the next frame. The BACK key restarts the frame when pressed within a frame. When the student is at the end of a frame, the BACK key takes him to the previous one. The TERM key associated with a code (up to eight characters) branches from any place in the lesson to the unit associated with the code. The students have to know these codes, so a good policy is to implement a page which is accessed via TERM "term" where all codes and associated material are displayed. Some other keys are also distinguishable, namely the DATA, LAB, HELP, and ERASE keys. DATA and LAB keys allow the author to implement more branching than only the two regular branching NEXT and BACK. The HELP key is generally used to give some hints to the students when they are confused. Fin- ally, the ERASE key enables the students to erase part of their answer or whatever they write on the terminal (the shift-erase erases all the characters written by the students) . 12 3. THE LESSON 3. 1 Purpose and Scope The lesson was written to give some basic knowledge about information structures. The principal topics covered in this lesson are the following: linear lists, i.e., stacks, queues, and deques; and linked and sequential storage alloca- tion. These concepts are introduced to the student and ex- amples are provided to illustrate these concepts. For stacks, queues, and deques, precise graphic representations are shown on the screen and the student can insert and delete items to acquire a better understanding of how these structures can be modified. At the end of each topic, a set of questions on the material presented is available. As it was said before, the lesson is intended for college students beginning their studies in computer science. The les- son is self-sufficient, i.e., no particular prior knowledge is required and terminology is introduced where appropriate. 3. 2 Description The lesson can be divided into five parts: how to use the lesson, what the lesson is all about, introduction to in- formation structures, linear lists (stacks, queues, deques), and storage allocation. Drills are associated with the last three parts to allow the student to see how well he has assim- ilated the material he has just gone through. 13 1) How to use the lesson - This section explains the three "modes" the student can select: a) see all the text and drills, b) only text, or c) only drills. This section also ex- plains how to use the NEXT and BACK keys and what their purposes are. Finally, in this part the "term" options are explained. 2) What the lesson is all about - This part introduces all the topics which will be presented later on in the lesson. In this section is discussed why information structures are im- portant in computer science and what one can do with these structures: how to manipulate, modify, create, and delete them, and what the basic omponent of a structure is. 3) Introduction to information structures - In this part the concept of information structures is actually intro- duced to the students. An example is used to ease the under- standing. The representation of a deck of cards is used to show a node of a structure and its different fields. With the same example one can see how to access the information of any node through links. Information structures are not static so a basic algorithm to add a new node is shown. Two drills are associated with this part. First, a set of questions dealing with the accessing of field of several nodes. Secondly, the students are asked to type the two basic steps to insert a new node to a very simple information structure. 4) Linear lists - At that point the students are sup- posed to know what an information structure is in general, so 14 in this part a special kind of information structure, linear lists, is introduced. Then the various sorts of linear lists are described: stacks, queues, and deques. For each kind of linear list definition and properties are shown, then a graphic representation is displayed on the screen. Finally, the stu- dents can insert and delete elements to these lists. This part is ended by a set of five questions randomly chosen from twelve questions referring to the basic properties of these linear lists. 5) Storage allocation - Up to that point no precise mention was made about the actual implementation of all the data or information within the memory. Two basic techniques to implement information structures are described: sequential allocation where data are in successive locations, and linked allocation where one field of each node is reserved to point at the next node so that consecutive nodes do not have to be physically in contiguous memory locations. A basic technique for handling linked allocation is also discussed: the use of a list of available space. In this part the student is asked to formulate the logical steps to insert and delete a node in a stack and in a queue. 15 4. EVALUATION OF THE LESSON When developing computer assisted instruction, the following question occurs frequently: how can the effective- ness of a teaching program be measured? Most educators believe that the basic purpose of learning is to change behavior. If the student does not do anything differently at the end of the learning experience than he did at the beginning, what has been the value of the program? As previously stated, the purpose of the present study was, in part, to write a lesson in TUTOR language for the PLATO IV computer assisted instruction system and to evaluate the effectiveness of this lesson. The experiment which will be described was designed to accomplish this goal. Two groups of students were given the same test to evaluate how well the lesson objectives were attained by the students and to provide a relative measure of the effectiveness of this teaching method, 4.1 Choice of the Students The students who participated in the present experi- ment were members of a University of Illinois computer science class (CS 201, Professor Mickunas) . The students were under- graduates (except for one graduate student) , mostly of junior or senior standing: 16 - one freshman - one sophomore - eight juniors - six seniors - one undergraduate irregular - one graduate The Class had no unusual characteristics and most of the students had no previous experience with automatic pro- grammed instruction. Finally, both groups of students par- ticipating in the experiment had no prior knowledge of the material covered by the lesson. The fact that these students had no prior knowledge of the material presented in the lesson was the main reason why they were selected for this experiment. 4.2 Procedure No pre-test was given since no students were familiar with the material presented in the lesson. Upon completion of the instruction sequence, both groups were given a test, so that the test scores could be used as a variable for analysis. The questions used were to test how well the objectives of the lesson material had been attained. The test contained fourteen questions. The test was scored on the basis of the total num- ber of correct responses. The average score was 11.3 or 81%. An outline of the score appears on page 17. 17 OUTLINE OF THE SCORE 6 9 10 11 12 13 43% 64% 71% 79% 86% 93% Test Score Percentage Number of Students Percentage 1 5.6% 2 11.1% 4 22.2% 2 11.1% 2 11.1% 4 22.2% One point should be taken into account when considering the information presented above. The test seemed to be insuf- ficiently difficult to provide a full range of scores; the lowest score was 6 (43%) , and the test limited several stu- dents, i.e., three scores of 14 or 100% were obtained. The students participating in the experiment began by receiving an introduction to the PLATO IV system and becoming familiar with the student terminal and keyset. Then each group attended one session of the lesson. The longest completion time was about twice the shortest, giving a ratio of about 2 to 1. The short- est time was 45 minutes. 4. 3 Students ' Comments After completing the lesson the students were asked various questions, and to write a critical evaluation of the PLATO IV system as well as the lesson. 18 Some students' attitudes toward media may not be a direct measure of their educational values. However, it ap- pears that student attitudes that are related to how well they felt they learned are good measures of effectiveness. The students were asked whether they "enjoyed using the lesson to learn this material." One student disagreed, three were un- certain, twelve agreed, and two strongly agreed (no one selec- ted "strongly disagreed"). The overall attitude of the students toward the use of PLATO IV was highly favorable: 82% of the students were favorable to PLATO IV, only 18% were uncertain, none were unfavorable to the use of the PLATO IV system. Most of the dislikes expressed by the students concerned technical problems associated with the teaching program. They expressed dissatisfaction with some fragments of the lesson, almost exclusively with some lengthy drills. However, some students noticed that they were worthwhile. Students also felt the need to ask specific questions about the material which was often not contained in the "help" sequences. As it was discussed previously, most of the students were not familiar with the PLATO IV system. Some students ex- pressed that they had various difficulties in reviewing parts of the lesson or in skipping to another part of the lesson. Such facilities were provided mainly via the NEXT, BACK, and TERM keys and explained at the beginning of the lesson. How- ever, some students had difficulties using these facilities. 19 This may be due to a certain lack of efficient explanation and/or due to the fact that most of the students were not fam- iliar enough with the PLATO IV system and were inclined to use only the NEXT key. In effect, the introductory explanation of the PLATO IV system was very brief and it seemed that more time should have been devoted to this part. 4. 4 Conclusion From personal communication with some students who took the lesson and from the results of the test and the evaluation, it seems that computer assisted instruction and particularly the lesson written by the author can be used in computer sci- ence for introductory courses. To summarize, the present study has shown that the les- son material can be taught on a computer assisted instruction system such as the PLATO IV system. However, the students felt a need for more flexibility in the lesson, so future work in this area should involve better designed and more extensive "help" sequences, references, and facilities to branch any- where in the lesson. 20 LIST OF REFERENCES Bitzer, D. L. and Johnson, R. L. "PLATO: A Computer-based System Used in the Engineering of Education." Proceed - ings of the Institute of Electrical and Elec tronic " Engineers , 59 (June, 1971) . Qfin-fifi. Bitzer, D. L. and Skaperdas, D. "PLATO IV: An Economically Viable Large Scale Computer-based Education System." Paper presented at the National Electronics Conference, Dec, 1968. Fry, Edward B. Teaching Machines and Program ming Instruction. New York- McGraw-Hill, 1963. Knuth, Donald E. The Art of Computer Programmin g. Vol. 1. Reading: Addison-Wesley , 1969. Meredith, J. C. "Machine as Tutor," in The Educational Tech- nology R eviews Series . Englewood Cliffs, New Jersey: Educational Technology Publications, 1972. Smith, R. G., Jr. Innovations in Teaching and Training . De- troit: American Data Processing, Inc., 1968. Stolurow, Lawrence. Computer Assisted Instruction . Detroit: American Data Processing, Inc., 1968. TUTOR User's Memo. "Introduction to TUTOR: PLATO IV Version." University of Illinois, January, 1973. 21 APPENDIX 22 The following documentation of the source code of STR1 and STR2 follows the sequential construction of the lesson. Each unit is discussed individually, and, where appropriate, placed in the context of the portion of the lesson it affects. For each unit the information generally given are the follow- ing: 1) purpose, 2) entry points, 3) units joined, 4) units from which it can be entered, and 5) units to which it can exit. The BACK and TERM keys are not considered in the follow- ing as a way to enter or exit a unit. Units : welcome titre comm choices exp STR1 loads character set and branches to the current unit returning from CSCOMMENT, otherwise jumps to the next unit. entry point: ret entry from: initial unit encountered exits to: titre displays title page joins: uarrow, rarrow, darrow, pressend entry from: welcome exits on selected key press to: comm, sansfin describes how to make comments joins: comments, wait entry from: titre exits on selected key press to: exp, yy describes the three "modes" entry from: comm, and any point in the lesson on "term" option exits on selected key press to: term, choices describes how to use the NEXT, BACK, and TERM keys joins: wait, pressend entry from: choices exits on selected key press to: term, choices 23 term more dispa dispa2 intro info card deck display explains what the "term" options are joins: pressend entry from: exp, and any point in the lesson on "term" option exits to: the next unit or previous unit when entered via "term" option introduces the lesson joins: wait, pressend entry from: term exits on selected key press to: dispa, term shows the structure of the lesson entry from: more, and any point of the lesson on "term" option exits to: dispa2 branch unit to the main parts of the lesson entry from: dispa exits on selected key press to: sansfin, intro, card, Hist, stack, queue, deque, alloc, sequen, avail, linked general approach to lists joins: wait, pressend entry from: dispa2 exits on selected key press to: info, dispa presents nodes and fields joins: concern, wait, fig, darrow entry from: intro exits on selected key press to: card, intro represents a deck of cards as a list joins: wait, fig, pressend entry from: info exits on selected key press to: deck, info continuation of card joins: fig, wait, pressend entry from: card exits on selected key press to: display, card explains how to refer to a given field within a node joins: wait, display2, nota-1, nota-2, algo, adl entry from: deck exits on selected key press to: newcard, yy, deck 24 newcard Hist opper opl oppms op 2 opdel de!12 opcomb presents an algorithm for placing a new card on the top of a pile entry point: neca joins: algo, waitn, depile, wait, stepl, step 2, adl entry from: display presents text on linear lists joins: wait, pressend entry from: newcard exits on selected key press to: opper, card explains how to access a node entry point: opperl joins: wait, linkl, k entry from: Hist exits on selected key press to: noper, opl, Hist shows the accessed node with a circle joins: uarrow, pressend entry from: opper exits on selected key press to: opins, Hist explains how to insert a node in a list entry point: opinsl joins: linkl, wait, k entry from: opl exits on selected key press to: nopins, one, op2 , opper shows the insertion of a node in a list joins: insll, pressend entry from: oppins exits on selected key press to: opdel, opper explains how to delete a node from a list entry point: ol joins: linkl, wait, k entry from: op2 exits on selected key press to: nopdel, dell2 shows the deletion of a node joins: delll, pressend entry from: opdel exits on selected key press to: opcomb, oppins presents the combination of two linear lists joins: linkl, wait, rarrow, node, pressend entry from: dell2 exits on selected key press to: opsplit, opdel 25 opsplit op 4 opleft stack destack popush jl pop push queue explains how to split a linear list entry point: opsplitl joins: linkl, wait, k entry from: opcomb exits on selected key press to: nopsplit, op4 shows the splitting of a linear list joins: wait, pressend entry from: opsplit exits on selected key press to: opleft, opcomb explains some operations one might want to per- form on a linear list joins: wait, pressend entry from: op4 exits on selected key press to: stack, opsplit presents text on stacks joins: wait, pressend entry from: opleft, dispa2 exits on selected key press to: destack, Hist shows a representation of a stack joins: figstack, statop, starrow entry from: stack exits on selected key press to: popush, stack prepares the insertion and deletion of a node in a stack joins: figstack, rarrow, starrow, shown entry from: destack exits to: jl chooses insertion or deletion entry from: popush, pop, push exits on selected key press to: queue, pop, push pops a node entry points: neg, ero, po joins: erarrow, topdo, topar, nodef, shown pushes a node entry points: null, pu joins: erarrow, yopdo. topar, nodef, dar, shown entry from: jl exits to: jl presents text on queues joins: wait, pressend entry from: jl, dispa2 exits on selected key press to: desque, stack 26 desque ppqueue qui ins-q del-q shows a graphic representation of a queue joins: f boxes, darrow, pressend entry from: queue exits on selected key press to: ppqueue, queue prepares the insertion or the deletion of a node in a queue joins: track, dotdot, front, rear, shown entry from: desque exits to: qui chooses insertion or deletion joins : next entry from: ppqueue, empty, full, del-q, ins-q exits on selected key press to: qui, deque, ins-q, del-q inserts a new item in a queue or in a deque (on the right) entry points: laO, lal, la2, la3 joins: clean, cadel, waitn, cadef, rear, frbntl, rightf, rightm, front, leftf, larrow, rarrow, rectan, shown deletes an item from a queue or a deque (on the left) entry points: dgO, dgl, dem, dg2, dg3 joins: clean, cadel, waitn, cadef, front, frontl, rear, rightf, leftm, larrow, rarrow, rectan, num, shown, reset entry from: qui, dul exits on selected key press to: empty, qui, dul deque presents text on deques joins: wait, pressend entry from: qui, dispa2 exits on selected key press to: queue desdeque, desdeque ppdeque shows a graphic representation of a deque joins: figdeque, pressend entry from: deque exits on selected key press to: ppdeque, deque prepares the insertion or deletion of a node of a deque joins: track, dotdot, leftm, rightm entry from: desdeque exits to: dul 27 dul side inslef t delright alloc sequen seq2 branches to next unit to test for emptiness or fullness joins: next, show entry from: dul, ppdeque exits on selected key press to: alloc, yy, dul, side chooses on which side deletion or insertion is to be performed entry point: es joins: next, insertt, deletee entry from: dul exits on selected key press to: full, empty, inslef t, ins-q, del-q, delright, es inserts an item on the left side of a deque entry point: ilO joins: clean, cadel, waitn, cadef, leftm, leftf , lrarrow, rarrow, rectan, num, rightf, shown entry from: side exits on selected key press to: full, dul deletes an item on the right side of a deque entry point: drO joins: clean, cadel, waitn, cadef, leftf, rightm, larrow, rarrow, rectan, num, shown, reset entry from: side exits on selected key press to: empty, dul introduces storage allocation joins: al, link4, link5 entry from: dispa2, dul exits on selected key press to: insist, sequen, linked introduces sequential allocation joins: as, pressend entry from: alloc exits on selected key press to: seq2 , alloc explains how to delete and insert a node in a stack and a queue joins: as, pressend entry from: sequen exits on selected key press to: seq21, sequen 28 seq21 avail avail2 linked link3 additional information on sequential alloca- tion joins: wait, pressend entry from: seq2 exits on selected key press to: avail, yy, seq2 explains the use of the list of available space joins: ava, pressend entry from: seq21 exits on selected key press to: avail2, link3 shows how to use the list of available space when inserting and deleting a node from a stack joins: avb, figstack, rarrow, darrow, step, pressend entry from: avail exits on selected key press to: linked, sequen introduces linked allocation joins: lp, link4, link5, display2, pressend entry from: dispa2, alloc exits on selected key press to: link3, avail prepares to insert and to delete a node in a queue entry points: j2, j21, j22 joins: linkl, depress, delins, next entry from: liked exits on selected key press to: miss, insert, delete insert J3 chooses after which node a new node is inserted joins: delins, next entry point: link3 exits to: j3 branches to insl or ins2 entry from: insert exits on selected key press to: insl, ins2 insl delete inserts a new node joins: nearer, insll entry from: j3 chooses the node to be deleted entry point: j4 joins: delins, next entry from: link3 exits on selected key press to: dell, del2 29 dell deletes the selected node joins: nearer, delll entry from: delete exits to: j21 yy implementation of jumpout to the lesson STR2 entry point: insiste joins: schaus entry from: termd, seq21, dul, newcard, dis- play, choices exits to: lesson STR2 or insiste if not enough memory available sansfin exits the lesson entry from: any place in the lesson via "term" option exits to: "choose a lesson" page STR2 start2 loads character set and branches to the current unit returning from CSCOMMENT, otherwise jumps to next unit entry point: retr entry from: initial unit encountered exits to: idrill ques loads in n38-n41 code of the answer entry from: d21, d41, d42, d43, d44, d45, d51, d52, d53, d54, d55, d56, d57, inter, drilld, drille exits to: expp expp judge unit for the previous questions entry points: exp2 , rel, stuck, rb joins: depress, sho, locate, errors, eral entry from: ques exits on selected key press to: exit-g, jul, idrill, erase, erasel, h-d2 exit-g branches to the end of the drill entry from: expp exits on selected key press to: d23, d45, d57 jul judges the answer of the student entry point: ju2 joins: locate, press, arrow entry from: expp exits on selected key press to: h-d2, erase, erasel, return, ju2 30 erase erasel h-d2 idrill drilla sep fill branch fuite qi erases the last character typed joins: eral entry from: expp, jul exits to: expp (rel) erases all the answers of the student joins: depress entry from: expp, jul exits to: expp (exp2) help sequence entry point: 11 joins: errors, jd21, jd22, h-d211a entry from: expp list of the drills entry from: expp and any place in the lesson via "term" option exits on selected key press to: sansfint, drilla, drillb, drillc, drilld, drille first drill entry from: idrill exits to: sep sets a permutation entry from: drilla, fuite exits to: fill displays three nodes filled with random numbers joins: random, press entry from: sep exits on selected key press to: branch, drilla, exitl decides to stop to ask questions joins: depress entry from: ql, fill exits on selected key press to: fuite, ql ends the drill and displays the number of errors joins: nextlab, rerrors entry from: branch exits on selected key press to: xx, xb, idrill, drillb, sep presents the questions to the students entry points: a, c, qex joins: press, errors, help2, random entry from: branch exits on selected key press to: helpl, exitl, branch 31 drillb pressents the second drill joins: skip, wait entry from: idrill, fuite, inter, d2 , 3, salir d21 asks the first question of the second drill joins: jd21 entry from: drillb exits to: quesll inter asks the second question of the second drill joins: wait, larrow, jd22 entry from: return exits to: quesl2 d2 3 shows step2 joins: wait, rarrow, nextlab entry point: exit2 entry from: return exits on selected key press to: drillb, drillc, drilla, idrill, xx, xb drillc presents the third drill entry points: retry 3, ici joins: head, wait, skip, depressl entry from: idrill, d23 exits on selected key press to: salir, aOO aOO displays the questions and judges them joins: show, text, al, a2, a3, a4 , a5, press, help3, errors, newques entry point : aa entry from: drillc exits on selected key press to: ici (drillc), exit3 (salir) salir displays the number of errors made on the third drill entry point: exit 3 joins: wait, nextlab entry from: drillc exits on selected key press to: xx, xb, drillb, drilld, idrill drilld presents the fourth drill joins: skip, assum, use, wait entry from: idrill, salir, drillc, d45 exits to: ques211a d41, d42, d43, d44 second, third, fourth, and fifth question of the fourth drill entry from: return exits to: ques211b, ques211c, ques212a, ques212b 32 d45 sixth question of the fourth drill entry points: exit4, ret4 joins: depress, rerrors , nextlab entry from: return, drilld exits on selected key press to: xx, drilld, drille, idrill drille presents the fifth drill joins: skip, assum, use, wait entry from: d45, d57, idrill exits on selected key press to: ques221c, drilld xx, exit5, d51, d52, d53, d54, d55, d56 second, third, fourth, fifth, sixth, seventh question of the fifth drill entry from: return exits on selected key press to: ques221b, ques221c, ques221d, ques222a, ques222b, ques222c d57 eighth question of the fifth drill and displays the number of errors entry points: ret5, exit5 joins: depress, rerrors, nextlab entry from: return, drille exits on selected key press to: xx, idrill, drilld, drille xx implementation of jumpout to the lesson STR1 joins: schau entry from: fuite, drillb, d23, salir, drilld, d45, drille, d57, termterm, termm, termi exits to: STR1 or xx if not enough memory available xb implementation of jumpout to the lesson STR1 joins: schau entry from: fuite, d23, salir exits to: STR1 or xb if not enough memory available sansf int exits the lesson entry from: any place in the lesson via "term" option exits to: "choose a lesson" page 33 o u hi Ml hlO hi hi Ul'. M IP C X Z UJ t- o Z U II u •- r w >- j i <: X(/ii~>r-£30O -I K hi «/» Z *» in •♦ hi IM X r> o 0<* hi * uj uj u ■» ♦ «- 4- 4- ••• > a o hi a ♦ ♦ a 3 ♦ «- 3 »- • V) 4- • x a a 4-4-4- 3 3 3 4-4-4- r- t- r- ni co a z ♦ ♦ ♦ 4- * 4- te. »- U «J O O »- 1 z ♦ *■ _l 4-4-4- •» l/l' — • L>i3' al 3 "J 3 ■ji UJ 4- 4- X 4-4-4- o UJ I 3 X u XXX ■•o to o ♦ 4- •■* 4-4-4- » o < l_> tt *- X »-»-»- IT< X UJ « 4- 4- 4- 4-4-4- o e> o _J h« »- «/l v\ in «/■< <»1 » • a X «• 4- 4- >- 4-4-4- *4 o o « • ,_ V> »-• a ^* ^ ^~ • IT cr »- cr ♦ r r r r ' «M *^ •-* ^^ a U i- t — a •— • a' r- >r •C • • r «/> a Kf\ r —■ r <-» ~-> -— <*) -# •c IM X t- »•- r> m co <*} (*) *-t O CO IV <7 »-• 4 c • - "• •— .— > a ro - •• ♦ a » UJt- r >- p* c o O 3 O O u. £ »— ►- «o r r o r xi r r r = XI • r>- o 'D r~ e c o *4 m O O- I CD •> | • *4 C. • CV • C O 0> c . . i o- t\i r+ • • M ^- o> in — • o f) e >c — • c cr c- (v . -. . — . -i rvi -»> jn \ ■* s !\J O M » *+ •O" 1 * ITCCC— O- — — — 0> — C aa -*-» * a « r> a 1 -< a ♦ x » — « in o o x -a 3--«'\i- , M- < 0!It UJ -^ «/• u. w ir r u. ? J x i o a i/> o z I- •-< —t U. z uj 3 3 h hi >-«^ 7i- or a o 2 a uj x z r d o 3 r- ■* UOOT">» UJ UJ hi UJ u i u' ui T t- l/l U. 1 K »- U' Hi.' ►- K ►-<_ ^-< I ^ -- 1 — < "^J •-. NJ -H -^ — 1>- ZT-txnr-«'r'-'Yt y a 3UJl/)3«"5■ _J -J -J u-t o« ooru cz <-> •>ga »-_ix_i-»x _i~«x -«x-i so Ul u 1 u> 3 _J _J -I T o?- o*i_)o:*t.>zv>- x->-«0< ->x>-OU0 03U000 ~>U")J3 ■ r> -t \i •» «■ n -.-•MMMMMM VJM MM -3->V)' r »4-'n0^t>> ») »l ■ 1 *) ■*» "> •>' r »' , 1'*> ■>-t\i-»>*no«-o>»3-« # * * * *'* * * * »• n n o 34 x x © to ui o «• Z o. Wi- lt* -J tfV I o O IT O © in «> iiti a or OIL o v> ZM • < X x O o W X UI m CJ Ui »- a o »- r •- o ►- » » IT »- V »- ■< «J Z uj -x u; r ff l T *~ M ■ 5 i. ^ >- V C D 4UJ w »- 7 z a a •-<•-< -i X x Z O O 3 -3 3 ~i 3 3 3 • "VJ »> * i> © «- n t) n n n t> m ui o — > s: o x i o (J O X 3- O O c o X 4- r CO o 3 o X »- 3 I z o »- x U I- 4- I X 4- IT 4- UJ «- c »- z «- < CM Or tt O ~ U- * UI 5C -* '3 ■*< 3 t-M X 4- — "K« 4- —• • UJ OP 4- 4- CM X Z - « 4- ■ u ' -* ci r ui T o ■? 2. UlbJ »- v x u u> f- H U I 71 « « z > 3 -« m »j t-n o «- o ■*=>-« \i ■»> * n o — o >t> n r> o c o oo o o o o o »».^..«» •» «~, «.■>». »».v. •«. n ui J a. U X uw < a u -1 z X M z »- X •-• o m 3' Uli >-• O CO UI >-' UI 3jC 1 >■ X • Z -1 UI < t- UI 4- •-• X o u. or a < < u. o o UIO. 4- > *~ UI o 1- X UI < 4- Ul-I U.-Z l-Ul! «- XX zoo 3 X i- in 4- *- J O 1- O U.I- «- z Ul _l >-iZ »- >- o o 4- Z«-i l-O O o Ul-.t— ZU3UMID I- OK X ►- «- X _*•- Ul z •- a. » >- a •-■ »- O UI3 o • UI «- UI X UJ I o X K X »5£ O O u> -1 Ul> «/> Xm i- ui oa •-• -J X 3 «- X x»- a •-• h-»- a or ui O < ♦ UIUI 3 UI 4- z a x x i ui »-© 1- UI o •-• U. «- »- K X >- < in «• »- UI «- 1- UI _l o 1- (/) UI 4- • > * Z_l -14-3 UI I Z UIOD 1- UJ s-" O a ►- «- x < IflJ UI UI X 0. - < i-« v:OX •«.'.•- 1) 4- >Uj! o: CD I- < < < u»*: 3 UI' »- »- U 07 «- X O UI Z >- a o ♦ •-• (/> CD «no J4UXC UJ «• a «• \n _i ai- «■ z x u o z om 4 UJ UJ •— UJ 4- UJ 1- UJ 3 1- _l «- 1 X X 1- < XX -1 «r x a z ui »- • •- z * • 3 • 3 U' X 4- CC * a * ui UI «l » i-tlUK ^ i «r »- ►* «- UI it "■ C 1 I o ^ r-»- c — « k- <— i * -7* n Of — u O •■* » 7 -T x o «- o 4 HUI < >- < a _J u. X or o o j: o ar i r - IT i UI ui r to u. >- u i- i- UJ X UI ¥~ 3: ^ r a u UI > .* ^ ri-< UI a. ►- tn •- \- Z O K z e i- z •-C ►-< *- >-• »— * *— •-• t— • 3 arzt o O X o O X o D lll.Hl -JO* -> o ■*. 3 -h v •) ♦ nn*-o>3-*\i*»#nn»-t>>»-^M D X) J) T> OD X)T> D>7>J>'>'> ?>>>> >>>3 » 3 35 Ul o «/l Ul Z X UJ O •« I «-»oc •- •-U o. •- © «/> 3 — o XI OD o I/) Ul z o (/) in X _i o z a. *■• Z W) ♦- ♦-•n. z mi. v* —nn ui z ft ""•- o a mmU ♦- ac »*. •' >-_» xac jwou attkt- Ul 3 a jiflo. o« UJl a a do a. 3 o o *-•«■* a «_> z < UJ3I •- a oz a »> *- x x •- OX x» UJ u I •- a o ui x i- u X ♦ •- « CO a 3 ♦ o ♦- o taj*- z a ♦ UJ x •-*- X ♦- ♦ UJ X e o e Ul o o JO tD*~' < o < «-l _l - UJ •— « *r X •* i -a o > or x I f- O U' ui • »- «/> I ♦ © ♦- I -X 4- — ♦ »J -« r ♦- t m\ z o a — u *- en ~ a: —i x • j ui t s »- ♦- *-> a a a a. ct rr < ** • " ul O < WliJ =° * * »- t ui *- •- r r • • o •-• a uj o a • n u z ♦-co 3< ♦- i/v 3C ^i' J- ♦->•-• _l «/> _l UJ UJ Ul X XII- l/> o U! UJ If)' o o *" 9 • • • UJ ♦ ♦ ♦ in •-< o c t- ~ w or a", a Z Ul ac U' o. e z •-• V) W Ul u ■ a o z 4 U < VI •-• o to ir z Z O UJ »-. •- >» I X I- »»- c < u. _i I aim _i cr e •- u; o c x r a: u u. • r- 3 z x c »- LiJ — t O 3- U r ■* -■ 3 »- •- tr • a * 3 I- II »- *- •— > «J l/l H < UJ o 1 S X. t Ul: IT UJ cr a o z z o o c _l _l «' UJ (9 < X o l/l • I/) ct u c a: U. D i/> (_; Z 3 •; a X UJ _l z «* o Z X -. Ct »- o 4 U UJ Z a — u X 4 o a U 3 I- (/) o X 3' x ac i- »- •-■ in a c o er 2. _i •-• « >- c ►- ct Z I- ui is> « UjC U 3 » 1-4 UJ IlCW U Z (/> Ul 4 U X I a. z o o o o a i- z •-< «- i r a x ui ♦- ^ << -j i ui < Z 1) * Ul »- ir ♦- «• 1 T « ■>-»\i»» t no'- o> MMM1*)">'*1'*)'*' o , n'O r >'-*--** *'* * ** ** -» \i •» * n r>' n n n i\ n n M< ee >o«j 36 •— -i UJ -i or x < X Ul •l T X — i UJ cj Z «X o a. •-> V) « UJ Z OJO o oc «-• _!•«»- Z _l _J « C «a •"-> O •-« ■« o I- -I > _J <[ <. <. _J CJ •"• « o •- u. _l Z O 3' J UJ al <3 »- *: 3lft2 [xMii — — V> V l/> O If) _l _) ¥ Ul UJ < o 3 3 a: • • • «* UJ o o U) u. © »- 3 u 1 »- »/> c o m < I (J3 I I "- B > 3-t\l«( t fl Id M ft. Ml •»« o tat z in »~ «n «- UJ x a * a ui «■ >- Z tr GO «- #" Ui a> *• x z 3> UJ > UJ z «n «s © x UJ or a o z UJ •-• •• I o o »• »- CO • • in z < z a • c 3 rr •— »- • »- ui m L> r • • ^ "• tr. z < in u. o in (/) U! u: ~ a x o a i- > • * —■ u — . r o r in x — >■ c XT* -« < w «/» «- UJ oc o a *■ i- o *• z • z ~ «- X < UJ +■ C X z «- =5 W 4- •« O «- •-< > z tal O tat o U tf> c «- 2 •-• "^ *■ X' >- o »- -o UJ «-« » «■ f> >- x — uj «~«o * v ~* «- ■* z t~ — «- «- r> at — -* «- r -* U' r- — «- -■ n »— -* -* tvj «- • f. c in x o •— * •-« »- r r»o !-• — *-> -a x oc x a: a: o 3; 3: 3: O "> * l»J l/i © • • O U.I 3T »■■ < UJ cj a o • a o »- • z CD •-« * Z O ►-< • u, uj in a o •* Z l/> c •■ 4 • «v a r rvj ^< »-^ o: ta.i Zta. M O ■ ta. «OZ OWO < «3 ac ac ui > »- o a. >- mZ JVI4 _J •- 4 »-0C 3 OO Iff ZX O X Ul •-• w or Z or in_i o UJO o _»>• a cd z a. «•-> >- or >■ k&|li/l uj t- uj r 3U)I- 0. UJ 5. I • OHIfl O Ul «- W3 UJ -J I/) < •c > — U r j cv *~ < o t/5 U «*> O •-• • 2 a »- UJ < 2 3T •= « 3 r «- z o »- or ui Ul (/) cc < I- Ul I z © o • UJ Ul 1/1-13 KO o z < Ul »- X z t> UJ< 3 J UJ » 4 or .l-'O < ■<*«».: a z »- * ui m o X U' »-_! Ul a z Z X o UJ •"- u«o T z Ul t- a >- in o ul V) or u. V) UJ z UJ J- Ul X (J X 2 in z ^ < a •-' uj cc •-. * x »— ii I UJ "— > in _j < uj z ~ ►-• r • CO o — <3. <-* O ^ r in -i UJ X in i z Ui Z UJ o •—I X tal z o z ui > o 3 o a z < ui o UJ t>: UJ' x X z Ul X Ul r o •—I r »- JE •-• I 3 tatr e Z tat< Z Z o o u ; Ul' I X' o X 2 • * o a »- z «-• •i r • (VJ it c O X < -< ii i- H >- < •- Ul O 4 ^ r a ui ui »- Sf K UJ W- *~ M(J O < * Ul z c »- z O O X o "5 13 3r ->l n«'-o>'3-»\in J) O/j O^no*- * n o *- o j- ~> -« v n- * o •^ O O B B B B o «». o > ? -• \i 'n fnc>'tii'o-i\i')tno»t BBBBJ>>'TT > '>'>>>3>>3'3 3 03 3 333 r __^„ rt ^^- OD H-l Z W X « z O • X 4 kit C • a X I ta. tal z o t- 3 4 X Z V) ta. -i tal X O 3 O Of X 4 (9 »- •-• O tf> •-i z a* a •- tal X 4 »-• tal Q 3 u >- >• -J X X Q -IZ tal • * « ♦- Z talO X > > a •-« t-t KU 4 tal ■X ta. ►■* »- K X »-• I-UIO K tal X tal V Z X z < X © cr> a 4 3 X talH -1 -I •-» z »- »- — -I < X •-* «_> tal t/> a —• 2 K 3 X O tal 2 O IE Z a X »- »4 O tal i- in -13 Z V) ta «/) « in 4 4 a o Z ta; a T •- tal >- a •-4 Q I tal O t- X < a. n tal (Ji > -J 4 Z -1 tal o tal 1-4 _l en t-i tal ■ — o — o • o • ►- in tal tal w>~ h-i <—: ¥- ta. Z O tal IA • »- T ot 4 vi — 4 a: ta- a M IT tal ta' tai o k n r> ♦ i- « i/i u i- i*" O 4uiJ1 « tai X O X .T X U.I o tfli a 3 u tal (A' Z' o o tal X o X a o tal Z o ta.. O in •-• in z o • «J > a talO 3 X Otal Z X i a U tal 4 i- tal 3 * a s III o + o VI ■H tal + T VI »- ■K ' «• U * *. — IKuiO X c C • ta (VI Z IT >-■ o •> •-« sc • U M 4 in x r^ ii • ' V fV tal -• «: l>- (9 X O * * -> \j t t n o •»■ o r ■> N * n o VJ M VI M M M (\l rvj ro rvi rvj iM ta' u- tal v u a ►-►-vi/i^to *~ rotairta.4 »- zor^ i-tKO-a'-''-'*— ►"• Mk- O •-• 3 _l •-• mu.(5 Ztal4rOOO»-X OOODOUlt-X QO-« 3TDtal">">lS4* -)i9I II 04 V "JiDu. M\i\i')'0'O»i'»>n.-0-n')»»*» ** t -t ■*■ * * M IM IVI i\l 'M i\l IVj i\l f\l V fV (VI l\l M i\l 'W IV c\i M IV .\p (M tat in o tal a tal Q •-• r> > »-• o O tai mi -^ p-*' U.I tal O O (V. z X X C X •t I ■I _l « O u o ta' o ta 4 ta •-• ta z tal ^ ta Z •-4 «- »-< •-< » •■ •> ^ HI k X o + o -* u 4 VI < rvj ^1 T ■K a -— C X »- M r^ «■ t- ii h> m _1 1- ii •-• > c —* V r cr — i tal •— . > 4 taJ f— 1 < UJ ac »— * tv — * 0O~)4 «-)ii) > .3 -• v •» + no— o>3 ♦nnnnnnnnnno rvi«vifwi\j{vj «m (\j ivi ."M rvirvjcvi 38 t> Z UI K UI U UI • a o a • o ae ui •-• X »•. Jd. 40 o z oo IA •-• u J o >■ c a zo U o to x< lA<»-l - OZ O 4 z 40 Z V) xz -I Ol UI z 4 UI UI (A on -IE UIUI •-»- o U U K- 4 > a i z « »- < U! • 1 01 h cr 4- UI X ins: * o VI Z ■H X «- Ui • ♦ z 1/1 UI a. UI V) VI o o ac a. 3 UI UI o o: >- o (A UI ac a ui a. u -I 3 e-« O 3 U. O UI or > < < U X IA o r (J <* cr ■ ii f, *■ o •- c © *: ^->>»«-r-tct«-ivc (vI 4 4 UJ 4) (VJO 4 Z UJ 3lC4»"*aQIicN r»>r o«->o X < X UJ a I a: * « «-< o r • o < — ♦ » CC • I- H I- H I- > < O O < UJ o r r * jt r u c. «- 4 »■* ^* r r -*. -* -• "\l X o UJ c o z I o UJ I- < I I*- 3 ♦ • r o 4 r «- IA «- * z «- 4 «- ac «■ K «- U) o o UI u (A (A. • z o a o a 3 x u UI u UI 4 X U I- IA IA •-• Z' 4 a ui ac X 4 ■-4 x ■ uj • O X C 4 K a *- 4 r* IA o r z • m « X (V UI o r^ -sr 4 »* ar « o n i- n CA CC 3 X o u • II • z z <1 « CE ^ UJ UJ UI UJ t~ ZO l-U'OZZO I- I- •■^ »-*►— ** Z — !•—<•-•*— •— • »-^ »-cr oo^-i«4ooo»-i: i-cr 4* 10 4UUTT04 I 4I» C G G OO OOOO^^-'^'^'^^-^'^y- NNIM nj UI l-IChUJiri-l-70l- 4 t- hU)-cKm _|i-« ?4liJ4XXiXODT: UIQC Doziijjiiino' o« V UJ «r Z O K UJOOI 5: ui ! Ol >t>-« \in * /» a •- t> j»->-«\j-o* nx>«-»> 3-*-\i-n*AA'-'0 j» 3-»Mn* aj (Vt\i«\i<\jf\jfvjcvi(\i(\ifvj(\j«\i'\i'>i(\i(\jc\i(\jf\j<\i(\jf0f , >( r >f0( , o« r ifn meo <»)(*)mn<»>f 39 hi © Z O J -J -i O o z o z o Ul IA Ul a a u a ui X o »- f ►- Ul •-I — «3 U.' a m 3 or a ^ r q. tf> o ui ♦ or *• o ♦ u ♦ >- a o X in CO x UI • a * c o o U) « O ~ • r * a e zou X »- * in «n to o a>»- z 3a o _i< i UU4 X •- o z » a a © 3 3 a UI U! uuo ♦ ♦ «• o c e f (VI 11 1 a O .» « <: a +~f*i o o <_> iT >- O 4 y - a o O O IT C 3 o — r r r r r ■* ■£. t) —• < ^ o •-• M — 'MM >■ a »vj i-HK- »->-»-►-»- a 1 C * C « O ►- >- a « -a « -3 «3 roou.»ou.»ou.»*f r r f r r • UI : Ut >- tr i/io^ou. ►- Z ■ O ~« - t • D*>:a_.\|«»*n">^01»:»-« '■•'-•M \IMMMM\IMM\l») , l iinnmi'irininni'i.ifii'in IxJ ui ui > v r-V»-ymUi»-U'OZ4«J7<»->Z «UJmNJmJJ«JJ« Z t iu -j (r-< i h« O'jJ a o »i « o o o je DdLZsuim *ino~)oo->ao~)">o * C K I- Ll UJ UI 111 W V K ►- * n o*"-t>j>-»-«\i'*>* no»- o>'3-«vi , *>-»oo»- -o ■»><■'> -n-n-n »>.■»>♦.♦..»■* * # # t * * n n n n nnnn n firif»>i'>for)«*)(»>r>ornn" r i mm mmmmmm mmom ui tn c 3 Z Ul o UJ o I z u> ♦- o z UJ «-" o i- ui 3 All r- in *n xl ~ o sc UJ UJ z cr X X UJ CL » •-or + ¥ ♦ r- r- O — « c c •— u> ^ «*) — • « *. u I r o r r r — z u UJ m • 4 <£ e r «z _! IV *. «-4 »— ^- (V _• *- »— !\J o 3 X X> — • (/" <\ 1*1 •a ^-* «— t l\J ^ UJ •■ a - » • • I — Ui t~ ►- II c »- ►- t— t— t— ■-- r — >■ (V <• T < — — »- «j ui ;M n o o o o « jt m m r r rr Ul UJ U I U I UJ UJ *-:*C in ►-»-»- r- r o o \~ x t or x cr '•"jO'iUIBJjtljJt or ^-•\J'^*no~•o^ nr>-Doorix>oij ooo mmmmmmmmm mmm 40 Mi O 4 S Mi a «■ VI VI « «■ z ♦ VI o 4- Ul (/) v> (Z a < -i a. in 1/1 c- •-> ♦ Q -« •-" eft. en tip t> *> *> p- ^ nio 1 3> a. «-<-** -* »— f\iT«v» • m m 75 <»> ♦ »nc(v * • en c c •* ^- a — < uj t-UtCxMo: tcrvmtcrtc t-riKi o • ni«io • n i 4 a o «■ «~ o a: o z <\i -« o x o z <\i ~« o a o z it *: ■# Al ~ r ■* ~ © C- IT IT m •* n • •-« m a • • (T « »- «" * «I •■no «v -« r «- VI «i «• 0B« Wi >■ Ulf JO a. X Ul «-»x uo Z»-- O OX z •-•-J V) < Ul o> cc z o Z UJ 1 o 3 O u. t/». O 3 — -1-1:4- ul ui m HHM b. u i/) Ul C UJ X HIK K Z © UJ z u. tr M O «* ae a u- u. u. x r u < « a z * ui UJ o X o t- z HI u < — ' u. ~ * — Vi (A O Ul z o O O o z z « II •-> — a. -~ o © ui — — z x a ■H I- 4- s: © © ni — 4- z I- • « i~ 4- ■~ m — ♦ ■ 3' 4- O — -I x 4- M UJ 4- I- © •-• Ui «- -. u 4- »- J£ 1C ♦ «■ «- z — •-i z »-• «r ♦ «- j ♦ 3 « « ♦ 4- X 4- in a © h- ♦ * z ♦ o M IT I X < <•> H- o ■«■ at Z OJ o 0C o Ul in. Ul to o Ul Ul -I •I < uia. ►»• ui tr viui < X > OK' I o I— 4-OL XO 4- I- UJ «• z zo 4- i a x m< l/IU UJ a x a ui 4- Z — © r z — tj r»> < M_J • a o »- © — in ♦ JN z «v 4- «* — C V tfl » 1-4 -« •-• M X Ui — •3Zi ~* »/)_l M m >* — < > CM a * i/>o oo o -J * UJ U' U 1 Ui ui _i _i _J a uj »- »-u_'uzo7'ou©~oz"ouj«jrozor , >- ►-• >-«2_J»-<_l>-lX ? JM JMI; J J^ JMI )IH !>«** JOTOTUJOTUTUJUTOTyu.J» Z I- X 3 < X Z »- X 3 < X Ul Z X 3 Jt < —u X Z 4 a * om fici i')f)( , )onir' , )( , )ni»)n(*)nfli , )C)cn , )i')i»)o^)(»)i») > > >'3> 3 t> 3 -3 * n c «" o » ■» -«m O O 3 3 3 3 -4-«.^. -«-«-• -<.-« -«.-« \J\J 41 z*> *- a. o Oil UIO Oini o Z • in u. x o o a. z a o « z uj *: w z UI •-* a o m z UI «n ui x a U' ec o «- ♦-a 4 »- Ui 2 a UJO. •-< « z uj C > _l z r o o oj» V IjJ _l _l _IQ »» S m k => UJ a i/> l_> >- < < a _j it a _j a n k k o o tn _ > ►- ~ > »- u < »- ►- a uj a O D * <. uj z -i t n o - o M M M VI \J \| \j Mil 1 liin -n*) »>•)■* * * * * n o t JO. kl»- o in ni u z o Ul in o a in o o «■ «- X X ♦ «■ U.' UJ ♦ «- z z «■ «- 1 • in in in c in UJ cr UJ a X i a M a ^ » a » * • e * ■a U ^-* UJ • «-* UJ r z -c r z m • CD • (V k (V -— PI • T r>j <-> T n •a -* • rvj 4 r\j jr Q. :n < M — *■ cr • f- -c fV .— d ♦ «\ ec IT a »- K ii a X a o • (V r— a e a H ►- it • UJ < — > rv cv tv rv r- • t Q X ♦ u •a »— > •* a o ~ t~ o 1- »- -i a UJ f> — • C »M i/i r lit in r jr kt {T « AJ Uj UI UI u UI UI -I -J k i- r o ir. ur u u u 1 o t; l* i- — • « ■-• »-. < <«Tizaj-« «-• Z(root-i'-a:--"-"<'< di-i 3JTa ■5-«\l 1*flO»tlJ'3HVI1 * -» *nnn nn nnnnno c oo.n Ui »- i- z o UJ UI m i/i u. 1 •-♦ »-t— • i— * < 2 z "root— it—a*-* Z! I104U 4aJ J no^ X))» 3 -« M »> J0OOJJX)-~>- — «-• 42 M> Ul Ui Ul UJ a «- o «■ o Ul X a o o «■ ♦ u a o o • ■& a v) "I- "it -3. T •c *■ o oza J3 r _i >■ a: o _i -J < 4 3 «• » X X o Ul z z o 2. Z Ql o z «- UJ «- z Ul a x ui • >- -O <- UJ -> z r a. ■ a a ox a < a u a. < x all Ul Z z I- Ul z tn 1- «- Ul «• z a «- o *• Ut i/> se •-z «_> => »- a t- t- i. O V? -4 UJ M UJ UJ z z *~ c »- K <3 UJ OX) _l UJ 4 -I a _j a • CV S. <-« »— II H o »- a >-< > < o -a inn- o z Z Ui •-• _l o •-• a a. a ui *■ z O H-< «■ H- U. «- O (/i a a o ui »- UJ It u.' z z Z O •a Q 3 4 •X X (V : • • a »- »- u. \r. in ¥- U1UJ o 4 ex ui z ui — < *+ O — • 3 -• i c • <*> l-(E U)(\l «- 4 _J — x a. •* «■ in i <*• U) z < a (v> a 2t ui — oiuJS® NtLa." Or < ui z -I ♦ f-l r <\l in »- a 1/lUlQ ►- a a _i a. X u < .-h — z < uj < a o o V UJ X IT. z o *- ■a ^ •-• «-•►- •-< z art-oroooz u U4 mo 3 >- Ul < z z o •- uJ O O O I Q -> "> tD * z z z o o o U) UJ i-t 4 •-« Z Z»- I UJ U! > 5 K-»-*:i»J«/'i«'h-« (T ?ut«J1lf> J 1 ul IP m if) ul X> ..-• vi »> * r> o •» o in in ui ji x» xi if> in "•VIMMMMM^ IAI Z' O 43 DC U a o o ■♦ 3» o 3 t-t M hi' in o X * •- i z z — UJ X z *■* ♦ •-• •-• o 1 •It X • tlill ** • 'Z X • o 4- • •* • >■ ~ UJ HZU1 IK w k o a X O ♦ > z V) -1 l-t. MZU UJ C I *•* O K X O UJ w Z > U. X _J O * • o •» O > (/) «- • UJ • - A 2 2 o Ui o — • in z •-• o A O o ** UJ -4 »-■ Z o z ♦ o j: u.!>->- z ue o o _i -< J. 1 r — z. t _i t/i •— • »- »- X c i- < o «- l/t *: «- t— aj uj •-> a. a 1- *- UJ > < » z uj X ii. X IT -J _1 < UJ > • »- «> (/)•-• t- UJ a UJ »» «/) k ir i • UJ I r •-• uj < •— < »- Z X »- tX ^ _l _J #-« V O n r «/> uj _J r * -J in « n uj a m a •-• V _! N« • O *" X c — c o IM (V ►- ~ U r- — u. — r? *4 -4 lT _l ^1 —4 .— « Z z uj • • UJ < cr • ** UJ Ci ~i/i t- I- 0. Z H n »~ X r z x - U'H ^ c i- z i-< M i-t b-« ►» »-H »-• oc <-• oc o ^J X o ji (/) x o » "> *■ n >> -» -• vi "i * no — o > » -• \i •*> ■* .MMMOOO *)♦>•*»*) •) t 1 t # **•'* minminininininininininin.n»nininii OX V) & c till a.* a.- o or hi a o ui X UJ «/> ar o l/> o z o ♦ *■* r ■* IV n ~^ (M <\j O » .— z K OJ • it «a ro •— o c» * ^ o * r (V n <\j ^ z ui uj s ts> ►- K ir o e o ►* <-< < >X Z tiJ z at *~ nc cc o a 3 K1U4 JUI * no^-o»» :> ■■« m « ♦.-*■ * » n n a mininininminm a o in o Ui 3 »- C -I o uj *- z •-• z u. < X * — 1- UI ♦ X X »- o 1- X z Ul o -< X u. •— M t- o z o J O (/) UI -1 »- »- X o z u. (/) UJ V) I/) »- Z UI UI z O X t> o •-• 1— o u ^•1 <■ •a UJ UI !T O Z X UJ o ■-« »-■ a. -J o • -• a. Z a l»> x u 1 « U) • Y- \ft a — X a in ^ ■♦ ♦ 1- 0. ~«u a •• a « ^i v\ o r o •• o • r •-• B -o a ■i * » eo IT _J •3C c C K rr a (Vi O r> v O • .i — ■ ITI < OJ Q •< ~-l ru a. • a 1— UJ •> a f - • *2 a a UJ ► o «/■)»- «r U' 1/1 1/) 1- H ii »; h < >- « u. IA ^- 2 z in r- a >- 4 ■a »— > I- < •— > a ■a • • — * >— i-i <\j CL _J X o •a U) i-i o <. UJ a t ^^ •-# a a _i ■-< • o _t UJ K r at »: _i r M ■< o UJ »- ;tr > > o o -I > fu UJ I UI UJ UI V a? i _» \— ^ •— • ir >- -» c z ♦- T O or *— • — u a H 1- VC — l_> ~-t i_) I < •-• ,_, »— »-• »-4 "^ \- hM r <—t- T •-• X OO T 7 O -> * n o UJ »-< -»x "> * O z cc < o ••> * n o «- T> »> "> •-• M *> -t r> nnrtnnnnoooooo minifiu*iinif>u^if>if»tnir»inir *o e x> o ^- *- in vn i/nr in in m n * n o m m in in m 44 W»i ec w a.' s bl Z o o w o I— C Z' UJ o z bi bl K O b> bi Si o a: o lAi bl ac o Ul: V> > (VI 3 Z o o a y «-t bl •• o o z I •-4 > bl z 3 O Z bl in o »- (Vi «4 1- (VI ♦ a: Ui (MAI > > * ♦ o «* O z- in •=-4 o • in — in 2 • X • (A Z •— » y (VI a o • bl mz , > > • • bl a bl X 1- •*« r in c •o (VI IU »!/) in ►- m C • fW K -4 IV i r a o •> - «n in IT ♦ * •«- (VI O • a <■ — r> t. •♦ or •m o C <£ «/> a a 3> _jff • « _ U! L' O ifl i- C UJ V) o UJ \ii — -z a. 1/1 1 UJ UJ in -* m evi UJ •— IX - tin *-* in 2 c (\J (M 2 -• -* ^ UJ • ■— • c« IT •■ -4 o 40 m * Z-ONfl Ct •■ UJ 4 a: o ** a a o a. «i a ix OUJ ■a Z r j J. >- UJ a o ac UJ ie 'VI (VI :> > (v e a ii ii v Q. Q. a M M T O O O > > -* UJ a: a. a o 4t L'a ct m o a UJ > z o u. « -a u. t x o a: oiii ru. a. UJ O in •o r> •-4 «-4 ■c OJ f-4 i>-a mo b' a - <_> O _l •-• •* U- u bl -1 ►o t: — « 3-4 O 3 -< — i ■t ac o UJ X ~) 7 © o o -> 13 > or >— 2- UJ 1- •-• T f— • r 7 •—* o ~> X o a *__ .^ . ^ 5 X "> * u u ~> ■< U _l J ►-• 3 iaiOOl z •— < -> « X «-o r a t JMJ 2 < O 3 MUTT * •- ec ui uj k ■- ►- •?■ in ►-» r I-* »-« ^ z z r o < 3«ni UJ 2 i/> -•' * O »- QC 1- -> •« uj «a UJ i/ia • O bl bl t- t- m ft >-4 a Z(-!T t-I 3 < ie