On Generalizing the Concept of Hypertext Author(S): Michael P

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On Generalizing the Concept of Hypertext Author(s): Michael P. Bieber and Steven O. Kimbrough Reviewed work(s): Source: MIS Quarterly, Vol. 16, No. 1 (Mar., 1992), pp. 77-93 Published by: Management Information Systems Research Center, University of Minnesota Stable URL: http://www.jstor.org/stable/249702 . Accessed: 01/03/2013 13:01

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On Generalizing the Introduction of The core idea of hypertexthas been described Concept Hypertext clearly and accurately:

The concept of hypertextis quite simple: By: Michael P. Bieber Windowson the screen are associated with Computer Science Department objects in a database, and links are pro- vided between these both Boston College objects, graphi- labelled and in the Chestnut Hill, Massachusetts cally (as tokens) database 02167-3808 U.S.A. (as pointers)(Conklin, 1987, p. 17) Steven 0. Kimbrough (See also Nielsen, 1990, and Shneidermanand Decision Sciences Department Kearsley, 1989, for book-lengthintroductions to The Wharton School hypertext.) University of Pennsylvania Still, as is universallyrecognized, there is more Philadelphia, Pennsylvania to the idea of hypertextthan linked information 19104-6366 U.S.A. items that allow a user to explore ideas and pur- sue thoughts in a free and "non-linear"fashion. After all, well-designed standard computer ap- Abstract plicationprograms, including reporting systems and decision have has become an established support systems, long Hypertext quickly deliveredsuch at least to a in the of information capability, respectable paradigm design systems. What with their The success of in the software degree. hypertextsystems add, products market, on the value of linked information evident benefits as and the emphasis reported by users, is: more featured of related research all attest to items, (1) easier, richer, highly flowering activity of and rather the and of linking information; (2) system-level, significance staying power hypertextthan for main- rich information standard application-level,support creating, systems. Although and linkedinforma- has a numberof taining,exploiting, managing hypertext unquestionedbenefits, tion items Likedatabase the also has a numberof well-known (Bieber,1991). systems, concept pro- and user blems and limitations. This article reviews the reportgenerators, graphics packages, interface management systems, hypertextsoft- mainproblems and limitationsof basic (standard) ware can be seen as application-independent, hypertextthat constrain the use of hypertextin system-level tools for providinguseful features practical applications. Further, this article for specific applications. presents and discusses our "generalization"of the basic hypertext concept, which we call Our aim is to describe and discuss certain ex- generalizedhypertext. These generalizationsen- tensions at the system level to the core ideas of compass, among other things, automatic crea- hypertext,which we call generalized hypertext. tionof hypertextelements. Generalizedhypertext We have been motivatedto develop generalized promises to be more powerful than standard hypertextconcepts as partof a largereffort, fund- hypertextas wellas less expensive to implement ed by the U.S. Coast Guard,to develop decision and maintain. To illustratethese concepts, we support system shells, i.e., system software for describe the implementationof a decision sup- generating particulardecision support systems port system currentlyin use by the U.S. Coast (Bhargava,et al., 1988; Kimbrough,1986; Kim- Guard. brough,et al., 1990a; 1990b; Minch,1990). Our purpose in this articleis mainlyto describe these Keywords: Hypertext, generalized hypertext, concepts, the reasons forthem, and theirpresent hypertextcomputation, virtual linking, implementation. dynamic linking, decision support systems, informationpresentation The paper is organized as follows. In the next section, we present brieflythe core concepts and ACMCategories: H.1.0, H.3.4, H.4.2 vocabularyfor basic -hypertext,as well as certain

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problems and limitationsof this hypertextcon- representsa particularlink in the hyperdocument, cept. These problemsand limitationsare widely e.g., xx, which links nodes AA and BB. recognized. are the motivation They primary a user sees a node in a win- behind our concept of generalized hypertext, Typically, displayed which is the main focus of this article. We then dow, its buttonshighlighted in some fashion.The user the click- present the essential ideas of generalized explores hyperdocumentby, e.g., on a button, the hypertext, followed a discussion of our im- ing particular thereby causing by to find the internal of the plementationof the system. system representation link named by the button, to then traverse the link,to find the node at the link's endpoint, and to displaythat node as anothertext passage. The Basic Hypertext newlydisplayed node may have buttonsas well, Our aim in this section is to brieflypresent and which the user may employ in orderto continue discuss basic hypertext.In the followingsection exploringthe hyperdocument.Alternatively, the we shall contrast this with the generalized user may at any time decide to returnto an earlier hypertext system that we have conceived, node and explorefrom there. Users may continue developed, and implemented. Certainly,many in this way more or less indefinitely,thereby ex- existingsystems have richerfeature sets thanwe ploringat willthe hypertextnetwork. A particular shall describe in connectionwith basic hypertext, hyperdocument-a collectionof nodes and links but our focus in this article is on generalizations -may be thought of as an applicationwritten to the basic hypertextconcept. Further,although underthe hypertextsystem. Itis the system that we shall limitour discussion to hypertext,most providesthe general means forexploring the par- of what we say (when not describing our im- ticularhyperdocument. Thus, a basic hypertext plementation) can be applied as well to system may be thoughtof as operatinga select- hypermedia.1 traverse-displayloop. The user selects a button, the system traverses the linknamed by the but- The central in is that of linked concept hypertext ton, and the system the node at the far collectionsof information.A document displays hypertext end of the link,possibly using informationpicked be seen as a withnodes that are col- may graph, up in traversingthe link. lections of information(called, e.g., windows (Conklin,1987), documents (Brown,1987; 1989; Typical,basic operationssupported by hypertext Haan,et al., 1992),cards (AppleComputer, 1989; systems include: Halasz, 1988), informationitems (Bhargava,et al., 1988), chunks (or pieces of text) (Koved, * User-directed navigation (traversal(of links) 1988;Trigg, 1983), frames(Akscyn, et al., 1988)). and display(of nodes)) of the hyperdocument. Links between nodes. specify relationships They * Search and the user will have themselves and fall into display (forexample, may properties a search and the will are maintained the and provide string system types. They by system, search until it finds a node containing that are named or referredto by buttons (also called string and then will display the node). link icons (Conklin, 1987) and link markers (Halaszand Schwartz1990)), which normally are * Map-basednavigation (the system displays a found in the nodes. To illustrate,see Figure 1 graph (called a map or networkoverview) of (based on Conklin,1987), where nodes Window the hyperdocument,and the user may direct A and WindowB are presented as windows on navigationof the hyperdocumentbased on the the display. Withinthe nodes are the buttonsx, map, whose buttons,when selected, cause the y, z. What is displayed represents part of the correspondingnode in the hyperdocumentto underlyinghyperdocument (network of hypertext be displayed). nodes and WindowA is a links). representation * Creation, modification(e.g., editing the con- of node AA in the and Window hyperdocument, tents of a node), and deletion of nodes and B represents BB. Similarly,a button, e.g., x, links and their attributes. * Displayof linkand node attributeinformation The hypermediaconcept extends hypertextto types of infor- the name of the node at a link'sendpoint, mationitems besides text, such as graphicsand sound(Haan, (e.g., et al., 1991). the type of node or link).

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Figure 1. Central Hypertext Concept

? Proceduralattachment (link endpoints may be explain and discuss the keywordin question. procedures that are activated by traversalof The hypertextsystem might infer a link (and theirincoming links. These procedurestypical- thus the existence of an accompanying but- ly affect how certain nodes are displayed (see ton) by being able to recognize keywordsin ar- AppleComputer, 1989; Halasz, 1988; Koved, bitrarynodes and dynamicallycreating buttons 1988, and Thompson, 1990). out of them that are linkedto the appropriate nodes. With such However this basic keyword a capability, a interesting hypertextconcept buildercould text into a node and is, and however useful various simplytype implementations have the create of the needed of it have to be, a number of system many proved problems buttons and links associated with that and limitationshave been identified with this node.2 there is considerable basic et Clearly, potential concept (Bhargava, al., 1988; Conklin, in terms of the 1987; Feinerand McKeown,1991; Halasz, benefit-especially reducing 1988; cost of a Van Dam, 1988). For this article we are building hyperdocument-to having the system capable of but- concerned with the followingwidely recognized hypertext creating tons and links automatically. problemsand limitationsin basic hypertext(and in many current implementationsof hypertext). * Manualnode creation (Bhargava,et al., 1988; Halasz, 1988; Jordan, et al., 1989; Parunak, * Manual linking (Bhargava, et al., 1988; 1988). This is the node version of the above DeRose, 1989; Feiner and McKeown, 1991; linklimitation. Under the basic hypertextcon- Halasz, 1988; Jordan, et al., 1989; Van Dam, cept, the hyperdocumentbuilder builds nodes 1988). Basic hypertextsystems provideediting by using an editor to key in or to paste in in- features for linking existing nodes and for formation.There remainsthe possibilityof the creatingand manipulatingbuttons (link icons). hypertextsystem generatingnodes (alongwith These features axe highly useful to the builder-or annotator-of a hyperdocument. The basic hypertextconcept, however, does 2 Althoughwe willnot discuss itfurther, this feature is supported not inferredor virtual, of in the system we illustratelater. Other researchers have been encompass linking active in exploringthis sort of feature,e.g., in the contextof nodes by the system at runtime. To illustrate extended electronic mail systems (Ackermanand Malone, the inferredlinking concept (calledimplicit link- 1988; Harp,1988; Lai,et al., 1988;Jackson and Yankelovich, consider a with 1991; Schatz, 1988). Other researchers are working on ing by DeRose, 1989), system generatinglinks from content analysis on text (Hammwoehner predefined keyword nodes, whose contents and Thiel, 1987; Parunak,1990).

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embedded buttons)on the basis of user inputs, pertinentinformation before display(Beeri and in conjunctionwith existing informationin its Kornatzky,1990; Tompa, 1989). Forexample, database (Furutaand Stotts, 1990; Schnase displays specialized by type of user (novice, and Leggett, 1989). (See Feiner and experienced, e.g.) might be implemented in McKeown, 1991, for mention of work on this way. of it can generation graphicalobjects.) Again, *Cost of be that with such a the cost building hyperdocuments hoped capability et al., 1988; Jordan, et al., 1989; of a be (Bhargava, developing hyperdocument might et 1990a; Basic we note that automaticcrea- Kimbrough, al., 1990b). reduced. Finally, substantial tion of nodes is differentfrom hypertextsystems provide support quite procedural for in whichthe user which has been used buildingapplications may attachment(see above), a collection of to the of-nodes, interactively explore large modify-or modify display associated information.Nevertheless, much ratherthan to create them. more might be achieved by embedding * Network disorientation (Conklin, 1987; knowledge into the hypertext system Nielsen, 1990b; Parunak, 1989). This is the (DeYoung, 1989). For example, contextual often-cited"lost in hyperspace" problem.At- informationcould be used automaticallyto in- will explorationof a rich hyperdocumentcan voke filteringroutines in support of multiple easily lead to user bewilderment. Basic views of nodes. Also, nodes (and embedded hypertextsystems use map-based navigation, buttons)might be generated automatically,at logging of nodes traversed, and search-and- run time, by machine-based inferentialpro- display commands as tools for ameliorating cesses. There are many other possibilitiesas this problem. well, e.g., automated node creation and * Cognitive overhead disorientation: linking. displayed information (Conklin, 1987; With the basic hypertext concept and a list of Glushko, 1989). A main virtue of hypertextis some of its pertinentlimitations at hand, we shall that it provides system-level support for now discuss our generalization of the concept buildingsoftware that bothpresents cognitively and how this generalizationaddresses the list of tractableamounts of informationon the screen limitations. and makes easily accessible arbitrarilylarge amounts of associated information. In the basic hypertextconcept, however,the builder Generalized must explicitly design the application's Hypertext displays. System-levelsupport for tailoringthe Our concept of generalized hypertext is basic amountof informationdisplayed and its mode hypertext plus generalizations with regard to of display is functionalitybeyond that in the nodes, links,and linktraversal. These generaliza- basic hypertextconcept.3 tions are furtherextended by system-level support for user and domain contextual * Multiple views (Halasz, 1988; Koved, 1988; The aim of this section is to ar- Basic dependencies. Perlman, 1989). hypertext systems ticulate our concept of generalized hypertextby a limitednumber of ways to typicallyprovide presentingand discussing these generalizations. view nodes. For oer- example, many systems In the following section, we shall illustrate mit buttons to be with or without displayed the with example's from our and some offerboth a user's view generalizations highlighting, implementation. and a builder'sview for nodes. Otherviews not envisioned in basic hypertextare possible. As a means of reducing cognitive overhead, Node generalization nodes be filtered and transformedfor might In basic hypertext,nodes are largely document or card nodes: collections of text withembedded 3 It is not, however,entirely beyond the functionalityof some buttons and (often) graphics. Further, these hypertextsystems. As notedabove, some systems allowpro- ceduralattachment for altering node displaycharacteristics. nodes are explicitlyrepresented in the system. "Card-based"hypertext systems (e.g., Akscyn,et al., 1988; We generalize nodes in two principalways. First, Apple Computer,1989; Halasz, 1988), restrictthe size of while nodes be collections of text with nodes in some way in orderto limit-in a limitedway-the may amountof informationavailable on screen at any time. embedded buttons, under our concept a node

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may be any informationitem (structured bit a command.In basic hypertexteach analysis link stream, e.g., a document, a symbol, a picture, may be thoughtof as a command to display one and so forth)about which the system may reason. of the two endpoints of a link. This generaliza- Just about any sort of entitymay be the endpoint tion allows arbitrarycommands for operating of a link(including other links),and all such end- upon a link endpoint and is a richer concept points are considered to be nodes. Abstractly, than that normallyencompassed by procedural nodes are objects that may be named (referred attachment. in various or and to) ways (explicitly implicitly) Oursecond is that links need not linkedto other nodes. informationabout generalization Further, be in the Like nodes be declared in the and this explicitly represented system. may system, nodes, be inferred at run time from information contextual they may (including information) declarationsused to buildthe as well as be used the its linktraver- system, may by system during from other such as user at- sal Oursecond is that information, inputs, operations. generalization tached and context. In nodes need not be in the applications, fact, explicitlyrepresented buttonswill often indicate be inferred generalized hypertext system. They may virtual,i.e., (or the of such virtuallinks. These linksare at run time from presence computed (Halasz, 1988)) not untilthe user chooses to declarationsused to build as well as generated actually the system, traverse them. fromother information,such as user inputs and attachedapplications (such as TEFA,see below). Generalizinglink traversal For in the decision example, supportsystem sup- In basic hypertext,as noted above, link traver- our ported by generalized hypertextimplemen- sal is normally performed through a select- models are tation,(illustrated later), represented traverse-displaymodel: the user selects a button in the attached and application, TEFA, every (e.g., by pointingto it with a mouse and clicking declared model is also a node. Linked virtually on the mouse), the system finds the linknamed to model are the results of various every opera- by the button,traverses it, and displays the node tions on it and it. it, e.g., describing evaluating found at the link's endpoint. (Inthe case of pro- These results are themselves nodes, typically cedural attachment,the system may find a pro- document nodes with embedded and buttons, cedure at a linkendpoint. Ifso, the system calls are created in real time of the duringoperation the procedure,which normallychanges the con- system. tent or display of a node.) Linkgeneralization We generalize linktraversal as follows.Inference (indeed, arbitraryprocessing) may occur both In basic hypertext,each linkestablishes a rela- before and aftertraversal of a link.After the user tion between a source node and a single single selects a button,the system may performa series destination node, called the link endpoint. We of inferences in order to determine what the linksin two First,links generalize principalways. available links are (i.e., the system collects the forkinto links. Thus, in a may multiple selecting link ensemble), possibly taking context into ac- which names a link, the user then button, may count. Ifthere are several options available,the be asked to choose severalsub-links. among (We user is then promptedto choose a particularsub- call such collectionsof sub-linkslink ensembles.) link and to For laterwe shall see that the name of (when needed) supply parameters. example, (Alternatively,the system may invokea default.) a mathematicalmodel may be a buttonin a docu- is in orderto validate ment. such a the link Inferencing performedagain Upon selecting button, the refined successful validation, traversal routinewill infer that several request. Upon analysis the system determines (finds or generates) the are available, to run the options presently e.g., appropriatesub-link and traverses it. Traversal- model, to describe the model, and to suggest a which itself be a scenario for the model may complex inferencing pro- (data set) running (see cess and may use application-levelprocedures Figure2). Thereare also two hypertextdocumen- a that names a node. Infer- for in- -produces symbol tation options for adding a comment and or is then on that a user-declared link. encing, processing, performed itiating (i.e., explicit) symbol (e.g., for the purpose of formattingand Each of these sub-links, or linkforks, is traver- display). Usually,this final inferencingresults in sable by the system and may be thought of as display of a new node. Thus, our generalization

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Q File Edit Information Query Processing MaH Financial describe(&asset) The ASSET Cost Rnalysis Module calculates ship acquisition and E life cycle co _ ro__lde data which can be t f competing systems of sh Information Ruailable: del asset is CARDIDATEC (1) run 3st Guard H.Q. The model ass (2) describe (3) suggest-scenario f-c =: c_1 (4) add comment c-_-s =s c_ (5) start link c_1_p =: c_- c-1Lacq. 3:

c f_s -. c_ ( Display J Select c-f- -p - -Option 1 c-fpacq =:- l Cancel J Number-> p_f =: c_f_ N,. |I

The model asset calls asset-cer to evaluate c-f-cc, c-f.profit, c-.lcc and c_l-profit.

max Inferred Link Ensemble Associated With the "Asset" Button

Figure 2. Inferred Link Ensemble Associated With the "Asset" Button

follows a select-infer-traverse-infermodel. (For importantelement of our design concept is that more details see Bieber, 1992.) the application should declare-explicitly or implicitly-what is important to it, and the generalized hypertext system should exploit Use of the generalizations these declarationsin orderto inferlinks, nodes, Under our concept of generalized hypertext, and views. (This is done, in our system, through nodes are objects (declaredor inferred),and links the use of universallyquantified generalizations, declareoperations that may be appliedto objects, whichwe call bridgelaws. The purposeof bridge usually producing a hypertext document upon laws is to map terms in the attached applications completion. These generalizations are the out- (such as TEFA, see below) to expressions come of our intentionto construct a hypertext (nodes, links,and so forth)native to the general- system in which the cost of building hyper- ized hypertextsystem. Detaileddiscussion of this documents is greatlyreduced through automatic technique is beyondthe scope of this article.For creation of nodes and links on the basis of further information see Bieber, 1990; 1992; application-dependentdeclarations. System-level Bieber and Kimbrough,1990. Further,it is our proceduresthat implementthese generalizations hope that networkand cognitive disorientation workon application-specificdeclarations in order are reduced by inferencingprocedures that are to make the necessary inferences for automatic broadlyavailable for reportingon and explaining linking,automatic node creation,and supportfor varioussystem entities, notablynodes, links,and multipleviews of nodes, links, and buttons. An buttons. The essential idea is to employ a stan-

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dardformat to declare informationabout system which are formatted and interpreted in an entities (nodes and links);use generic (applica- elementarymessage managementsystem (Kim- tion-independent) inferencing procedures to brough and Moore, 1992). In Figure 3, A is the generate nodes, links, and alternateviews; and user, B is the communications path on which providesystem-level explanation features. messages from the message management and C is the locus of external We shall now illustratethese ideas witha discus- system flow, procedures (e.g., subroutinelibraries and commer- sion of our implementationof them. cial model solvers) and data (e.g., in database management systems). Illustration: a Shell Maxi is a standalone event-drivengeneralized Max, DSS hypertext editing and management system. It Maxis a generalizedhypertext knowledge-based dynamicallycreates user interfaceenvironments DSS shell. It is writtenin Prolog and is currently based on requests fromTEFA, which are tailored being used at the Research and Development using context informationabout the task and the Center at the Office of Engineering, and user (Halasz, 1988). As seen in Figure 3, Maxi elsewhere, in the U.S. Coast Guard.Max has two has two main components. The user communi- main modules:a user interfacesubsystem, call- cates directlywith the dialog subsystem, which ed Maxi(Max Interface),and a model and data handlesthe physicalinput and output.The (large- management subsystem, called TEFA (The ly) configuration-independenthypertext sub- Eileen FordAgency, model management being system passes informationbetween TEFAand such a "fashionable" subject). The two sub- the dialog subsystem, performing hypertext systems have no code in common and com- editing and inferencingas necessary. TEFAis a municate via expressions in a formal domain-independentmodel and data manage- communications language, the expressions of ment system currentlysupporting models that

KSS Shell

Maxi

------. - - - . .- - Hypertext TEFA - C Subsystem B

I A I 4 Dialog Subsystem

Arbitrary Application

ApplicationKnowledge Base

Figure 3. Max KSS Shell High-Level Architecture

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can be expressed as mathematicalequations. is not excessive because buttonsname-or refer Forthe applicationat hand, it provides a model- to-links, and these buttons are copied, not the ing language (whichDSS buildersuse to record links.) Executives, on the other hand, generally the domain models and data) and information do not buildreports. Instead, they typicallyread about the models and data (Bhargava, et al., reports produced on the system by analysts. 1988; Bhargava and Kimbrough,1990; 1992). Because analysts can easily includegeneralized buttons in their executive Maxi runs on a Macintosh com- hypertext reports, currently only browsers have access to the same standard TEFAis writtenin and is puter. generic Prolog and other informa- therefore reports generalized hypertext substantially configuration-indepen- tion as their This allows executives to dent. When not combinedwith Maxi it has its own analysts. the information the command explore supporting analyst's generic Prolog language component recommendationsand without and is in this in the findings placing currentlyfunctioning way undue burden on the VAX/VMSenvironment. For TEFA to functionin analysts. an event-drivenwindowing environment, these Imaginethat an executive needs to make a deci- commands are translated by the message sion based on the costs of two differentfleets, management system into the communications one consisting of hydrofoils and the other of language. SWATH (Small Waterplane Area Twin Hull) vessels. The analyst's task, then, is to perform an analysis exercising the Asset life cycle cost Example:Working with a cost model model to create a report. The steps taken are In order to give a sense of how Max works, we outlined in Figure 4. shall discuss some of the features a user would Steps 1 and 2: Analyst's Point of View. After employ in a Max application-called Max startingthe Max session, the analyst asks for a Financial-to workwith a particularmodel. We fulldescription of the Asset model. To do this he shall use as our example a model called Asset, or she selects the describe command/queryfrom which is used by the Navy and the Coast Guard a menu in Max's menu bar and the Asset model to estimate ship acquisitionand life cycle costs. as the subject of the command. The system pro- Asset was originallyimplemented in Fortran.We duces a standard report model description reimplemented it in the model representation (displayedin an interactivedocument), shown in language of TEFA. The various reports and Figure5. Buttonsare highlightedin boldface, in- features we shall illustrateare producedinferen- dicatingthat further information is availableabout tiallyat runtime by Max, i.e., by our generalized the objects they represent. hypertext system. They are automatically 1 2: Point of View. Dur- availablefor any model declared in TEFA.(It has Steps and System's Max's the MaxFinancial been our experiencethat this strategysignificant- ing initialization, application a list of command ly hastens the buildingof a particularDSS (Kim- (under TEFA) passed in the communications to brough, et al., 1990a; 1990b.) options language Maxi, the shell interface subsystem, which installed Maxwas designed to supporttwo types of users; them in the menu bar under the heading Max analysts and executive browsers (or other Financial(see Figure5). Whenthe analystchose readers of preparedreports). Each typicallyap- one of these items, he or she initiatedthe follow- proaches the system with a different purpose. ing dialog with the Max Financialapplication. Analysts execute models under various data scenarios. Informationis returned in standard * that are created the Dialog Subsystem reports dynamically by - user The can then and Intercepts input. system. analysts copy paste - Passes the a from these standard to create their own hypertextsubsystem message reports that the user selected the describe ad hoc final it is to note relaying reports.Again, important menu item and entered the text that Max standard string dynamicallygenerates reports "asset." and automaticallyembeds buttons that name generalizedhypertext links. Copying and pasting * HypertextSubsystem preserves these links in both the original and - Receives the describe menu item and duplicatecopies. (The computationalcost of this associated text string.

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Figure 4. An Analysis Task Supported by Max

--Determines that this is a generalized - TEFAgenerates a composite report con- hypertext link traversal request. taining this information(which Maxi will - Infersthat processing must be performed perceive as the destination node), formats by TEFAto determinethe destinationnode. it in the formalcommunications language, - Formulatesa linktraversal request to TEFA and passes it to the hypertextsubsystem. (which TEFAwill perceive as a command in the formal communications * HypertextSubsystem request) - language. Receives the link's destination node from TEFA. * TEFA - Processes the node's contents into a for- - Receives the describe command request matthat the dialogsubsystem can use. This with text "asset." input string involvestagging buttonswith an internalID - Infersthat the text "asset" string represents and formulatingdisplay information(e.g., a Max Financial model. the buttons'base displaytext, and whether --Infers the describe model for generic report each is textual, numeric, monetary). a (financial)model. - Passes the destination node's contents to - Executes the model for the generic report the diaglog subsystem. asset financialmodel. This involvesinferring the financialmodel's description,source in- * Dialog Subsystem formation,equations, and any related sub- - Receives an orderedset of text and buttons models. The knowledge base is used to from the hypertextsubsystem. derive these elements, many of which - Processes the data to create an interactive themselves are entities containingsubcom- document.The buttoninformation compiled ponents. by the hypertext subsystem is used to

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t File Edit Information Query Processing MaH Financial I I I I 1 IIdecr be( ass et)I 4? ' EM -n- describe(&asset) 85 and & The ASSET Cost Analysis Module calculates ship acquisition Q life cycle costs. The intent of the module is to provide data which can be used to evaluate the relative costs of competir~ systems of ships. The source / reference for the model asset -? is CANDIDATECRAFT STUDY (second analysis), U.S. Coast Guard H.Q. zi The model asset has the following equations:

f_c -: c-l-s + n-f * c_f_s

c.-_s =: c_l_acq + c-l_p zz c-lJp =: c_l-mp * w_mp + cph * n_h c_l_acq =: 1.335000 * p_1 =: c_-lcc + p_l c_l_profit ilij c_f-s =: c-_facq + c-f_p c-f_p =: c-f_mp * w-mp + cph * n-h c-,facq =: 1.295000 * p_f :f; p_f ": c-f-cc + c-_fprofit

STS? The model asset calls asset_cer to evaluate c-.fcc, c._fprofit, c_l_cc and c_l_profit. s

max P _ L -211: m. mom t:?f Figure 5. Standard Report Describing the Asset Model determinethe actual text representationof links),which is generated inferentially.Thus, we each button on the screen. say that a buttonnames a linkensemble, or bun- - Displaysthe interactivedocument shown in dle of links, ratherthan a single link as in basic Figure 5 on the screen. hypertext. The buttons in an interactivedocu- highlighted Step 3a: System's Point of View. What hap- ment denote real or virtual. links, Althoughthey pened internally is that the system interface indicatea relationto informationin the knowledge determined that the user clicked on a set of are not linked to base, they (usually) explicitly knownentities: the asset button,the reportnode, As we shall when are anything. see, only they and the interface window itself. By default the will a link be determined and queried directly system chose to take the most specific entity(i.e., traversed. the button) and translated its internal ID to its Step 3a: Analyst's Point of View. Next, sup- TEFAidentifier in Max's generic "Whatcan I do pose the analyst wants to execute the Asset with this?" query. To the options (sub-links) model undertwo scenarios. The analyst presses returned by the application (TEFA), Maxi's the (Macintosh)option key, and the "show me hypertext subsystem added the hypertext all available options" cursor appears as shown documentationoptions for commenting and user- in Figure 5 (near the upper right-handcorner). declared linking. The analyst then clicks the mouse on one of the "asset" buttons. Figure 2 shows the list of Steps 3b to 5: Analyst's Point of View. From available options (i.e., generalized hypertext this (filtered)list of options the analyst executes

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the Asset model twice, once with the scenario node comprisingthe majorresulting values was (dataset) "hydrofoil(l)"and once with"swath(l)." generated as the linkdestination (i.e., the node The analyst believes the variable "f_c" stands was created) and passed to the interface for forthe totalfleet costs, butjust to be sure, clicks display. on it to ask for a short The description. general- 6 to 8. 7 shows the final ad hoc ized are shown in Steps Figure hypertextreports generated thatthe has constructedfor the ex- 6. These standard are report analyst Figure reports quite ecutive browser. Note that the has had but could be made more analyst sparse, they explicitfor, to do no the automatic a novice if the explicit linking.Instead, say, analyst. Alternatively, only links were carried over the buttons total fleet cost were a with through needed, report only text in the via and this value could have been returned. (boldface figures) copy paste operations and editing of the final report. Steps 3b to 5: System's Point of View. Inorder Althoughthe final report is quite short, an ex- to execute the Asset model for the user, the ecutive or browsercan query any buttonfor fur- system traversed a virtual"execution" link (as ther detail(Bieber, 1992). Infact, a large amount opposed to the other options of traversing a of informationis availablein this fashion. Forex- "describe"link or a "suggest scenario"link, etc.) ample, in Figure7 the executive has queriedthe froma reportbutton for a model node. As a result value representing the SWATHfleet cost. The of followingthe execution link,the modelwas ex- system recognizedthat this buttonrepresents the ecuted, and, as it happens, a standard report resultof a model execution and determines that

| File Edit Information Query Processing MaH Financial describe(0asset) The ASSET Cost Rnalysis Moduie calculates ship acquisition and module run(Gasset,'hydrofoil(1)) is to provide data run(0asset,'swath(1 )) f_c = 3.165701e8 c_-1s = 3.448127e7 f_c = 2.1 10006e8 c_f_s = 2.820888e7 c_-ls = 2.289484e7 c_l_p = 9325000 c_f_s = 1.881057e7 c_f_p = 8150000 c_l_p = 9325000 c_l_acq = 2.515627e7 c_f_p = 8150000 c_f_acq = 2.005888e7 c__lacq = 1.356984e7 c_f_acq = 1.066057e7

1pD- 2what is(0f_c) ED! - The variable f_c stands for total fleet cost. ,^ !-

max 1K>11 c_f_cc, c_f_profit, c_l_cc and c_l_profit.

max - _____| ------~ i~ft~I i~i

Figure 6. System Generated Reports From Executing the Asset Model and Describing the f_c Variable

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I File Edit Information Queru Processing Man Financial I ' El 1O - Final Report 2 We used the asset model to calculate the life cycle costs for the swath ( 1 ) and hydrofoil ( 1 ) f Ieet scenar i os. The total fleet costs under each scenario is:

swath ( 1 ) 2.110005e8($) hydrca _

We therefor Information Ruailable: onfigurat Ion. -(I) eHplain (2) add comment (3) add user-link max r 1

~F~

Cancel NE b

Figure 7. Analyst's Final Report and Link Ensemble for SWATHFleet Cost an explanation can be generated dynamically. the cost and effortof creatingand using hypertext This explanationappears in Figure8, complete systems. By providing efficient and standard withautomatic links from the embedded buttons techniques for incorporating necessary and to providefurther information for the executive. recognized features, our generalization of the of provides a robust basis for Maxsupports many other features (e.g., explicit concept hypertext creation of nodes, links, and buttons; user- knowledge-based hypermediasystems. induced, machine-interpretablecomments on Our experience with the Max system has models and data) and contains several substan- demonstrated that generalized hypertext con- tial mathematicalmodels, but discussionof these cepts are both computationallyfeasible and lies beyond our currentpurpose, which is to pre- useful for builders,as well as users, of hypertext sent and discuss generalized hypertextand the systems. By way of summary,we shall comment essentials of our implementationof it. brieflyon the relationof generalized hypertextto the problemsand limitationsof basic hypertext, presented earlier.

Discussion and Conclusion * Manuallink creation, manual node creation. Hypertextis recognized as a method for reduc- Under our concept of generalized hypertext, ing the human operating cost and cognitive both linksand nodes may be eitherexplicit (as overhead of using information systems. in basic hypertext)or virtual(created during Generalized hypertextis a method for reducing run time by the system, based on inference

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* File Edit Information Query Processing MaH Financial I 1 ..._ Final - - - I J- 8C_LJ r Report PA a We used the asset model to calculate the life cycle costs for the swath ( 1 ) and hydrofoil ( 1 ) fleet scenarios. The a total fleet costs under each scenario Is:

swath ( 1 ) 2.110005e8($) hydrofoil ( 1 ) 3.165701e8($)

We therefore recommend the swath ( 1 ) fleet configuration. 2~ ~ ~ ~ ~ ~~ - 1-=r-I II-I eval(&f_c,&asset,&swath(l)) ' e I .I - I 2.11 0005e8 is the result of evaluating f_c under scenario I nax swath ( 1 ) . The variable f_c is: Total fleet cost i It is computed using the model asset as follows: f_c =: c_ I_s + n_f * c_f_s Here is the data used:

c_l_s = 2.289483e7 n_f = 10 c_f_s = 1 .88 1057e7 k<5l

Figure 8. System Generated Report Explaining the SWATHFleet Cost Number in the Analyst's Final Report

from general declarations).We have demon- so. In the case of DSS and model manage- stratedthis concept withan implementationof ment, it is fairlyclear what sorts of things are a DSS shell and model management system, important and hence should be used for called Max, which is currentlyin use by the automaticlink and node creation. The exten- U.S. Coast Guard.Applications of Maxbeyond sibility of the generalized hypertext idea to DSS have been developed to the prototype other application domains depends upon stage (e.g., forproject management and forex- whetherit is possible to state a general, broad ecutive informationsystems) but are not yet theory (set of declarations)regarding what is deployed. The generalized hypertextsystem important in that domain. Without such is indeed quite general and application- declarations (bridge laws or something like independent. Automatedlink and node crea- them), it would of course be impossible for tion can be thought of as being based on a automatic node and link creation to be declared theoryof what is importantto the ap- practicable. plication. In the Max Financial system (the DSS applicationdescribed above), models are * Network disorientation. We do not claim to important,data are important,and things that have a major advance on this problem. We can be done withthem (e.g., describe,explain, have, however, learned something that sug- run,suggest a scenario)are important,and the gests some progress in this area. Oursystem system contains internaldeclarations that say is, as we have seen, oriented toward helping

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an analyst constructan interactivedocument * Cost of building hyperdocuments. It is evi- with generalized hypertextfunctionality. The dent that by relyingon automaticgeneration analyst or documentbuilder can create one or of nodes and links through runtimeinferenc- more documents that are organized as the ing on general declarations, generalized analyst sees fit. Text and buttons can be hypertext can greatly reduce the cost of copied from other documents, normallygen- creatingspecific hyperdocuments.This is par- erated by the system, into a document of the ticularly clear for the application we have analyst's choice. (Again, this was illustrated chosen to illustratehere. In MaxFinancial the above.) Workingwith the system in this way, numberof virtualnodes is essentially infinite. the hypertextnetwork tends to take on a nice There is a generalized hypertext node cor- structure. Instead of being an essentially ar- responding to every possible parameterset- bitrary network of nodes (documents) and ting for every model in the system, but only a links, the hyperdocumentbegins to have the few nodes are ever actualizedin any given ses- structureof a collection of trees with a com- sion. Also, it should be emphasized that from mon root,where that rootis the document the the DSS builder's point of view the general- analyst is using the system to create. One ized hypertext features "come for free." begins at the document, forays out for infor- Specifically, models, data, and information mation, copies the information(including the about them are declared in a simple, buttons),returns to the document (witha click straightforwardlanguage. (The same tech- on its window), pastes in the retrieved infor- niqueis used in otherapplication areas as well, mation, makes any needed editing changes, e.g., project management.) Once declared, and repeatsthe basic cycle untildone. Similar- this information is fully available to the ly, browsersmay use a single documentor set generalized hypertextsystem. The builderin- of documents as a home base for exploration. puts (explicit)information about models and We believe this structure for hypertext ses- data, not about windows, buttons, and links. sions reduces the problemof networkdisori- Itis this latterinformation that the system pro- entation, but provingit is another matterand vides and manages. will be the subject of future research efforts. Finally,it might be asked, "Whatdoes generalized do for the user?" In one sense it Cognitive overhead disorientation, multiple hypertext does nor should it. and views. Because links and nodes may be nothing, Debuggers do not delivernew forend created automaticallybased on declarations compilers functionality users. make it easier and fromthe application,it is possible to set up the Instead, they cheaper to software. declarations in a way that results in salient produce application Similarly, on our chunking of the information.What counts as generalizedhypertext-based experience -makes it easier and to salient chunking,of course, is difficultto deter- cheaper producehyper- documents for those who can use them in their mine and willlikely be application-dependent. We have illustratedabove the outcome of our jobs. InMax, for example, a few pages of declara- choices in the context of DSS and model tions describing a mathematicalmodel (such as the Asset can result in thousands of management. How, in general, information model) (vir- links that can be should be organized for presentation under tual) hypertext generated the Most of these links hypertextis a propersubject for an extended dynamicallyby system. used. Without automatic research program.Generalized hypertext,as get generation, it would not be cost effective to we have presented it, does not solve this prob- however, simply set the links with a standard lem or complete the research. Instead, it up manually, i.e., editor. facilitates implementationonce a solution-a hypertext salient chunking-is chosen. By making the In sum, while we have installed a functioning application-specific declarations (including generalized hypertext DSS, there is still very contextual information)in the right way, the much roomfor further work. We view our current generalized hypertextsystem can be made to system as a platformfor investigatingorientation, present information in cognitively useful scaling, networking, and knowledge-base chunks, and this can be done in a context- maintenance issues, and particularlyfor further sensitive fashion (Bieber, 1991b). Much re- exploitingcontextual clues. We are improvingour mains to be learned on this subject. specificationsof contexts and task environments

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and are workingon incorporatinga hypermedia Generalized Hypertextand Model Manage- model inputand modificationsubsystem, as well ment in a Symbolic ProgrammingEnviron- as a hypermediaproject management system, ment,"Proceedings of the NinthInternational as standard features of the DSS. We are also Conference on InformationSystems, Min- modeling a "hypertext engine" to make neapolis, MN, November 30-December 3, generalized hypertext available to information 1988, pp. 179-191. systems other than DDS (Bieber, 1991). These Bieber, M.P. Generalized Hypertext in a are topics for forthcomingsystems and future Knowledge-Based DSS Shell Environment, papers, bothof our own and, we hope, of others. doctoral dissertation, University of Penn- sylvania, Philadelphia,PA, 1990. Bieber, M.P. "Issues in Modeling a 'Dynamic' Acknowledgements Hypertext Interface," Proceedings of Special thanks to Hemant K. Bhargava and Hypertext '91, San Antonio, TX, December ChristopherV. Jones forstimulating discussions, 1991a, pp. 203-218. ideas, and comments on an earlier draft. Dr. Bieber, M.P. "Template-Drive Hypertext: A Bhargavais largelyresponsible for the TEFAsub- Methdologyfor Integratinga HypertextInter- system mentionedin the body of the article.This face into Information Systems," working workwas fundedin partby the U.S. Coast Guard paper, BCCS-91-4Computer Science Depart- under contract DTCG39-86-C-E92204(formerly ment, Boston College, Boston, MA, 1991b. DTCG39-86-C-80348),Steven O. Kimbrough Bieber, M.P. "AutomatingHypermedia for Deci- principalinvestigator. sion Support," Hypermedia, forthcoming, 1992. References Bieber, M.P. and Kimbrough,S.O., Towards a Logic Modelof Generalized Hypertext,"Pro- Ackerman,M.S. and Malone, T.W. "Intelligent ceedings of the Twenty-ThirdHawaii Interna- Agents, Object-Oriented Databases, and tionalConference on System Sciences, 1990, Hypertext," in AAAI-88 Workshop,Al and pp. 506-515. Hypertext:Issues and Directions, St. Paul, Brown, P.J. "TurningIdeas into Projects: The MN, August 23, 1988, pp. 1-3. Guide System," Hypertext '87 Proceedings, Akscyn,R.M., McCracken, D.L., and Yoder,E.A. Chapel Hill,NC, November 1987, pp. 33-39. "KMS:A DistributedHypermedia System for Brown, P.J. "A Hypertext System for UNIX," Managing Knowledge in Organizations," ComputingSystems (2:1), 1989, pp. 37.53. Communicationsof the ACM(31:7), July 1988, Conklin, J. "Hypertext: An Introductionand pp. 820-835. Survey," Computer(20:9), September 1987, Apple Computer,Inc. HyperCardUser's Guide, pp. 17-41. Cupertino,CA, 1989. DeRose, J. "Expandingthe Notion of Links," Beeri, C. and Kornatzky,Y. "A Logical Query Hypertext '89 Proceddings, Pittsburgh,PA, Languagefor HypertextSystems," Hypertext: 1989, pp. 249-258. Concepts, Systems, and Applications. Pro- DeYoung, L. "Hypertext Challenges in the ceedings of the European Conference on Auditing Domain," Hypertext '89 Pro- Hypertext '90, Cambridge UniversityPress, ceedings, Pittsburgh,PA, 1989, pp. 169-180. Cambridge, England, 1990, pp. 67-80. Feiner,S.K. and McKeown,K.R. "Automating the Bhargava, H.K. and Kimbrough, S.O. "On Generation of Coordinated MultimediaEx- Embedded Languages for Model Manage- planation,"IEEE Computer (24:10), Ocober ment," Proceedings of the Twenty-Third 1991, pp. 33-41. Hawaii InternationalConference on System Furuta,R. and Stotts, P.D. "TheTrellis Hypertext Sciences, 1990, pp. 443-452. Reference Model," Proceedings of the Bhargava, H.K. and Kimbrough,S.O. "Model Hypertext StandardizationWorkshop, NIST Management:An Embedded Languages Ap- Special PublicationSP500-178, Gaithersburg, proach," Decision Support Systems, forth- MD, January 1990, pp. 83-94. coming, 1992. Gloor, P.A. "CYBERMAP:Yet AnotherWay of Bhargava,H., Bieber, M., and Kimbrough,S.O. Navigating in Hyperspace," Hypertext '91 "Oona, Max, and the WYWWYWIPrinciple: Proceedings, San Antonio, TX, December

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Tompa, F. "A Data Modelfor FlexibleHypertext Pennsylvania. His research interests include DatabaseSystems," ACM Transactions on In- hypertext, information presentation, and formationSystems (7:1), January 1989, pp. knowledge-based decision support. 85-100. Trigg, R.H.A Network-BasedApproach to Text Steven 0. Kimbroughis associate professor in Handlingfor the Online Scientific Communi- the Decision Sciences Department,the Wharton ty, doctoral dissertation, University of School, Universityof Pennsylvania, and is cur- Maryland,College Park, MD, 1983. rentlythe WilliamDavidson Visiting Professor of Van Dam,A. "Hypertext'87: KeynoteAddress," Computerand InformationSystems at the School Communicationsof the ACM(31:7), July 1988, of Business Administration, University of pp. 887-95. Michigan. He received his M.S. (industrial engineering) and Ph.D. (philosophy) degrees About the Authors from the Universityof Wisconsin. His research interests include hypertext, decision support Michael P. Bieber is assistant professor of in- systems, electroniccommerce, and logic model- formation systems at Boston College, Carroll ing. Since 1986, he has been principal in- School of Management.He received his B.S.E. vestigator for the U.S. Coast Guard's KSS in computer science and Ph.D. in decision (knowledge-based decision support systems) sciences at the WhartonSchool, Universityof project.

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