Research Gate See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/221513338 Group Decision-Making for Collaborative Educational Games. Conference Paper · January 1998 Source: DBLP CITATIONS READS 4 17 3 authors, including: Giannina Nuñez Universidad de Panamá 2 PUBLICATIONS 4 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: Portal Web Centro Regional Universitario de Veraguas View project Proj ect Propuesta de implementación de las TIC en los Programas Anexos de la Universidad de Panamá. View project All content following this page was uploaded by Giannina Nuñez on 09 November 2018. The user has requested enhancement of the downloaded file. Proceedings of CRIWG'98 • Fourth International Workshop on Groupware Quarto Seminario Internacional sobre Sistemas Cooperativos Cuarto Taller Internacional en Sistemas Cooperativos September 9-11, 1998 Arma~ao de Buzios, Rio de Janeiro, Brasil GROUP DECISION-MAKING FOR COLLABORATIVE EDUCATIONAL GAMES Giannina Nunez 9728105@atlas.cic.itcr.ac.cr Ulises Aguero uaguero@sol.racsa.co.cr Cesar Olivares coliva@sol.racsa.co.cr Centro de Investigaciones en Computacion Instituto Tecnologico de Costa Rica Abstract Human beings live in a dynamic world. We confront numerous situations that demand decisions at the personal level. However, in a globalized world, the performance of groups has more impact than that of the individuals. The presence of plausibility-driven group decision-making tools in collaborative educational games results in the following advantages: increased game dynamics, better group awareness, respect for different opinions and improved critical thinking. In this context, the purpose of this paper is to report on the main partial results of an ongoing project that intends to develop collaborative educational games as tools to improve the quality of the learning process in the presence of globalization issues. The focus is on the use of consensusbuilding techniques in a game's group decision-making activities. 1 INTRODUCTION Human beings live in a dynamic world. We confront numerous situations that demand decisions at the personal level. However, in a globalized world, the performance of groups has more impact than that of the individuals. As a consequence, effective group decision making techniques that take full advantage of technological advances must be systematically infused into society (see [DeKr60] [Jani72], [John81], [Mart89], [Mart92], and [Mert80] for discussions about the role of individuals and groups in society). In the presence of such clear need for building group awareness, modem education must certainly lead the way to reach that objective. The effort ought to start with children and develop towards higher levels of education, so to produce a solid foundation from where to grow. The power of networks in general, and the Internet in particular, must be fully exploited to create effective educational tools for group decision-making. In addition, many long standing educational techniques to develop group dynamics need to be reworked to take into account the new collaboration technologies (see [CaZa71] and [CiVi66]). In this context, the purpose of this paper is to report on the main partial results of an ongoing project that intends to develop collaborative educational games as tools to improve the 143 J i J quality of the learning process in the presence of globalization issues. The focus will be on the use of consensus-building techniques in a game's group decision making activities. More specifically, the paper bas the following objectives: I 1. Show the importance of collaborative educational games for modern globalized education. 2. Analyze the role of group decision-making in collaborative educational games. J 3. Discuss consensus-building approaches to group decision making, including a significant voting scheme that improves the effectiveness of the games. j To complete the objectives, the paper covers the following topics: j Team Work and Education. In this respect, it is interesting to note the strong relationship between group dynamics techniques and modern education. From this perspective, education uses the psychological and sociological strengths of group dynamics to form self-sufficient individuals that are capable of surviving in society and, at the same time, be integral part of groups [CiVi66]. Collaborative Educational Games. These games represent valuable tools for group-aware education. This because collaborative educational games (a) are entertaining and based on experience-driven heuristic learning, (b) encourage collaboration and (c) serve as laboratories for experimenting with conflict resolution approaches. The Theory of Plausibility. In the games, conflict resolution is rooted on consensus-building arguments, so that decisions represent the group better. This approach uses the reasoning principles of the theory of plausibility and a flexible voting scheme. Application. Finally, the paper describes the general nature of the design of a collaborative educational game to support the area of equivalent fractions. 2 GROUP WORK AND EDUCATION It is quite common to find comparisons between the so-called traditional and modern approaches to education [CiVi66]. Modem education considers individuals as intelligent organisms that perform in a social environment. For these individuals, learning is active problem-solving and not just memorization. Experience leaves in an individual a guide for action in future situations; therefore, a person needs to discover how to learn, how to experiment, how to act in groups and how to make decisions. In our societies, evidence evolves and so must decisions. As a result, children must learn principles, not details, so that they can adapt to evolving circumstances and decisions. Correspondingly, a group exhibits the following characteristics in group dynamics [CaZa71][CiVi66]: 1. A distinguishable association between two or more individuals. 2. Group conscience: the members consider themselves a whole group; there is a collective perception of unit, a conscientious mutual identification. 3. A sense of participation with common goals and ideals. 4. Reciprocal dependency on the satisfaction of needs; the group members need to help each other achieve the common goals that motivated the team formation. 144 J 5. The members have means to communicate among them. 6. Ability to act as whole. 7. The group has an internal structure, where roles are well-established. In this context, the following are eight basic principles that can guide the dynamics of team work [CiVi66]: 1. Environment: The environment must contribute to improve participation, spontaneity and cooperation among all group members. 2. Reduction of intimidation: The reduction of personal confrontation and intimidation among group members improves productivity. 3. Distributed leadership: All members must have the opportunity to fully develop their potential and initiatives to improve team capabilities. 4. Goal definition: All members should participate in the team goals definition to increase collective conscience. 5. Flexibility: The group must allow goal reformulation to adapt to changing circumstances. 6. Consensus: The group must establish a free and spontaneous communication in order to reach decisions by means of mutual agreements among all group members. 7. Process understanding: Group members must fully understand the rules for interaction and collaboration in order to increase the possibilities of reaching the common goals. 8. Continuous evaluation: The group needs frequent feedback about its progress in reaching the team goals. Many of these principles may be satisfied in the design of educational games based on collaborative consensus-building decision-making schemes. To achieve this educational goal, the use of computers and networks becomes a great asset when combined with the wellestablished discipline of group dynamics. In this respect, Computer Supported Collaborative Leaming (CSCL) is the term commonly used to refer to the integration of computers, networks and collaborative learning [SIGCU92], that is, the integration of Computer Supported Cooperative Work (CSCW) and group dynamics in education. 3 COLLABORATIVE EDUCATIONAL GAMES For the purposes of this paper, a collaborative educational game has the following characteristics: 1 1. It is based on rules and takes place in an entertaining environment-therefore, it is a game. 2. Seeks the construction of knowledge-therefore, it is educational. 3. It is restricted to the realm of computer networks and includes software components for players to participate and collaborate even when they are physically distant from each other-therefore, it is collaborative. Collaborative games do not intend to replace conventional activities; on the contrary they should be part of a series of integrated means to learn. 1 145 4. The different proposed solutions are discussed with the help of consensus-building tools, including threaded discussions, decision graphs and voting. All these are based on the Theory of Plausibility (see below). Figure I shows a sketch of the collaboration interface of a game on equivalent fractions. PLAY ..\ND VERSION CONTROL VOTING PLAYERS TOOLS CON~'EN~'US-BUILDING DrnC-'USSIONS Figure 1 : Work areas for a collaborative game. The sketch shows several areas. Some of these areas are visible to all players and others are local to a player. The following is the general functionality of each area: Play area: the main activity takes place here. In particular, in this area is where the players register their answers and manipulate objects. It also includes a version-control area. Players: it is a global area where the participants are identified and information about them can be requested. Tools: it is a set of collaboration and object-manipulation tools available to the players. Voting: it is where the players cast their votes, using white and blue balls to express agreement and disagreement, respectively (see the section on voting below). The voting process results are accounted for here, establishing a plausibility state for a given issue or proposed solution. Discussion: here is where consensus-building discussions take place. These discussions may be private or public, using group decision-making support tools designed with plausibility criteria-i.e., decision graphs, discussion forums and voting facilities. l J l 4 PLAUSIBILITY-DRIVEN DECISION-MAKING The Theory of Plausibility was first introduced as a basis for explaining the way computer architecture designers make decisions when determining the features of a machine[Ague87]. However, it has been used in the general area of group decision making, even at the commercial level.2 The theory of plausibility for group decision-making is based on two fundamental objects of study: plausible issues and plausibility statements. A decision is organized in terms of issues. During a step of a decision-making process, an issue may be in any of the plausibility states acceptable, satisfactory, doubtful, unsatisfactory, or undetermined, depending upon the evidence at hand. 2 For example, Virtua!Meetings™ is a commercial Costa Rican product based on the theory of plausibility, developed by CREADISA in 1993, to support group decision-making. 146 J I A plausibility statement is the structure used to make claims about the plausibility of a decision. Issues that qualify to be in the ace table lausib · state. to be in the sat.isfacto,,, pla11S1bili%y state. Issues that qualify t-0 be in the wuleurmined pla11S1bili%y state Issues that qualify to be in the doubt state Issues to be in the uns,tiefacto,,, plausibihty state. Figure 2: Regions of the plausibility space. During a design process, the plausibility of an issue may change from one decision step to another. As a consequence, an issue C may be in one of five plausibility states: 1. Acceptable: there is no evidence against C's plausibility. 2. Satisfactory: there is significant evidence in favor of and no evidence against C's plausibility. 3. Doubtful: there is evidence against C 's plausibility. 4. Unsatisfactory: there is significant evidence against C's plausibility. 5. Undetermined: it is unknown whether or not there is evidence against C's plausibility. This is the initial state of every new issue. The evidence in the above definitions may be any combination of the following three kinds: • Precise and formal, based on two-valued deduction theories. • Approximate (and formal), based on heuristic methods founded on less precise logic than two-valued logic. • Experimental, based on experimental methods such as simulation and emulation. Plausibility statements are intended to model claims about a decision in order to enhance a decision maker's confidence in it. , I r A plausibility statement may establish the plausibility (state) of an issue as being acceptable, satisfactory, doubtful or unsatisfactory. Plausibility statements are fundamental entities in the theory of plausibility. They are used to establish an issue's plausibility state for purposes such as: evaluating an existing decision; driving the development of new decisions; determining the advantages and disadvantages of one decision with respect to another; and supporting the plausibility of decisions. In any case, the use of conventional features such as anonymity and retraction enhances de decision process. 147 Based on the five states of the plausibility of an issue, some verifiable laws ofp lausibility can be specified (see Figure 2): 1. If issue C qualifies to be in the satisfactory plausibility state, then C qualifies to be in the acceptable plausibility state. 2. If C qualifies to be in the acceptable plausibility state then C does not qualify to be in the doubtful plausibility state. 3. If C does not qualify to be in the doubtful plausibility state and C does not qualify to be in the undetermined plausibility state, then C qualifies to be the acceptable state. 4. If C does not qualify to be in the doubtful plausibility state, then C does not necessarily qualify to be in the satisfactory state. 5. If C does not qualify to be in the satisfactory plausibility state, then C does not necessarily qualify to be in the doubtful state. 6. If C qualifies to be in the acceptable plausibility state, then C does not necessarily qualify to be in the satisfactory plausibility state. 7. If C qualifies to be in the undetermined plausibility state, then C does not qualify to be in any other state. A plausibility-driven voting model generates, for the decision maker, more flexible voting options. As a consequence, the decision maker may explain his or her position better. In fact, he may express consent and disagreement at the same time for a given issue. 5 A PLAUSIBILITY-DRIVEN VOTING SCHEME [0LIV96] In a group decision-making situation, there are decision makers and issues. As explained before, the plausibility state of an issue can be defined in terms of the evidence in favor of and against the issue, as established by the group. In a voting scheme, it is possible to gather that evidence by creating a variation of the Group Valance Model [HoK194). In a voting activity, issues frequently take the form of alternatives. The group evaluation is based on the evaluation of each individual and on the influence or weight that the individual has on the overall decision. When considering an issue, a decision maker should pay attention to both positive and negative evidence. The evidence in favor of or against an issue is represented in terms of a degree of approval and a degree of disapproval. The plausibility (or acceptability) of an issue is calculated by combining the evidence expressed by each individual. Voting Principles The voting scheme is based on five basic principles that represent high-level specifications or restrictions: • 1. Each decision maker may express both approval and disapproval, even at the same time. 2. Approval and disapproval may be expressed in different degrees. 3. Decision makers may have different influence levels on the decision. j 148 4. The degree of approval of the group is calculated by combining the degrees of approval of all members, adjusted with respect to their influence levels. Corresponding considerations apply to the degree of disapproval. 5. Issues are placed in plausibility states according to their assigned degrees of approval and disapproval. Voting Norms Derived from the principles, the voting scheme includes more specific norms to structure the plausibility-driven voting process, as follows: 1. Each decision maker is assigned a number of white balls and blue balls. 2. The number of white and blue balls assigned to a decision maker represents the influence level of the decision maker--i.e., his power within the group. 3. The degree of approval of a given issue o by a decision maker dis the number of white balls d assigns too. The degree of disapproval of a given issue o by a decision maker dis the number of blue balls d assigns too. 4. The degree of group approval of o is the algebraic sum of the individual degrees of approval, and the degree ofgroup disapproval of o is the algebraic sum of the individual degrees of disapproval. 5. The voting scheme includes the definition of an approval mark (mJ, a minimum approval mark (uJ, a disapproval mark (m,.) and a minimum disapproval mark (11i,). Ola must be between 1 and the total number of white balls assigned to the decision makers. Ua must be between 1 and m •. m,. must be between 1 and the total number of blue balls assigned to the decision makers. 11i, must be between 1 and m,._ 6. An issue that as been exposed to a voting process qualifies for a plausibility state according to the following definitions (see Figure 2): • Satisfactory: degree of approval greater than or equal to the approval mark and degree of disapproval less than the minimum disapproval mark. • Acceptable: degree of approval greater than or equal to the minimum approval mark and degree of disapproval less than the minimum disapproval mark. • Doubtful: degree of disapproval greater than or equal to the minimum disapproval mark. • Unsatisfactory: degree of disapproval greater than the disapproval mark. • Undetermined: degree of approval less than the minimum approval mark and degree of disapproval less than the minimum disapproval mark. Voting Policies A policy is a set of restrictions to administer the voting process. The following are the main types of policies: 1. The distribution of influence in the group. 149 2. The possibility of decision makers of establishing different degrees of approval (and disapproval) for competing alternatives. 3. The possibility of decision makers providing both positive and negative evidence for a given issue. 4. The consensus required for the approval or disapproval of an issue. Influence distribution policies Balanced: All decision makers have the same influence--expressed in the number of balls received. Unbalanced: The distribution of balls is not the same for all decision makers. Expressivity policies Expressivity refers to the possibility for decision makers to vote with different degrees of approval and disapproval for competing alternatives. The following are two examples: 1. A single approval policy limits decision makers to express approval for no more than one alternative. 2. A linear approval policy limits the decision makers to assign the same number of approval (white) balls to all the alternatives with a non-zero degree of approval. Evaluation policies The following are examples of evaluation policies: 1. Unidimensional: a decision maker may express either approval or disapproval for a given alternative, but not both.. 2. Multidimensional: a decision maker may express both approval and disapproval for a given alternative. Consensus policies. Consensus refers to the degrees of approval and disapproval required and tolerated when selecting one of the competing alternatives. ln general, consensus policies are expressed in terms of the values assigned to the approval and disapproval marks and minimum marks. The following are some examples: I. Fixed: the approval mark and its minimum are chosen based on the total number of white balls distributed among the decision makers. 2. Relative: the approval mark and its minimum are chosen based on the total number of white balls deposited by the decision makers. 3. Medium consensus: the approval mark is at least half the number of accountable white balls--i.e., distributed or deposited. Similarly, the minimum approval mark is at least one third the accountable white balls. 4. Low consensus: the approval mark is at least two thirds the number of accountable white balls; the minimum approval mark is at least one. 150 6 EDUCATIONAL GAMES AND GROUP DECISION-MAKING The types of multiplayer educational games that we are researching emphasize problems that allow for different correct solutions because they are better suited to discussions. We are not concerned so much about the strategies players use to find solutions, but on the evaluation of the proposed solutions by the group of players themselves. As part of the games, we want players to criticize and search for consensus on the plausibility of the solutions. Players will have at least three different group decision-making tools available in their search for consensus: a decision graph tool, discussion forums and voting faci lities. r Decision graph tool. This is a visual tool for the construction of decision graphs-and trees in particular. The solutions proposed by the different players or teams of players become, automatically, part of a predefined decision tree. The solutions represent leaves of the tree and have plausibility-driven evaluation forums (i.e., specialized threaded discussions) associated with them (see Figure 3). Fractions I No Name [] P-OR r Groupl []P-OR I Solutionl Solution2 Solutionl Solution2 □ Cl (!] CD I==== Solution3 Ci1 I==== Figure 3: A decision graph for the fractions game In the graph's nodes, specific icons represent plausibility states of the solutions; through laws of plausibility-that define the behavior of AND and OR-the plausibility states are automatically propagated from the leaves to higher levels. The states of the terminal nodes are determined through either evaluation forums or voting processes. Any team may create their own decision graphs to help synthesize their proposed solutions. The construction may be done collaboratively in real-time. Plausibility-driven threaded discussion forums. These are general-purpose forums where annotations to main entries can be labeled as annotations against or in favor of the entry. Evaluation forums-mentioned above-are specializations of these forums. Through an automatic analysis of the annotations, the plausibility logic engine is able to provide feedback to the players about the plausibility state of the forum entries (see Figure 4). 151 :§) 0 ULISES Mon Jul 27 16:28:31 1998 General Entry ffl ESTRE Mon Jul 27 16:34:01 1998 General annotation PJ IBARRANT Mon Jul 27 16:38:42 1998 Annotation In Favor Of &J LCAMPOS Mon Jul 27 16:40:13 1998 Annotation Against Figure 4: An annotated entry in a forum. Voting facilities. In the collaborative games, plausibility-driven voting is associated with solutions that, in tum, correspond to nodes in the automatically generated decision tree. Players will typically decide to vote on a proposed solution when they are not able to reach consensus in the evaluation forums. Players may also decide to vote on any general entry of a discussion forum. In order to vote, white and blue balls are assigned to each player based on predetermined game parameters. 7 AN APPLICATION The example is a game to experiment and play with the concept of equivalent fractions. It has been inspired on the work of [DeVa96][DuLe96][CaLe96][Quin89]. The game's general objective is to form a specified fraction inside a number of different pictures, using the parts provided. Only proper fractions are considered--i.e., those with the numerator less than the denominator. Educational Objectives The following are specific educational objectives of this game: • Identify equivalent fractions. • Derive the concept of equivalent fractions. • Experiment with fractions in general. • Develop group conscience through plausibility-able tools. • Experience the effectiveness of collaborative educational material through computers. • Complement the conventional classroom activities related to a difficult topic such as fractions. Game Guidelines The following are the basic game guidelines: 1. Each participant must place one of the pieces provided on each of the pictures. 2. The game is played in rounds. During his or her turn, a player has exclusive access to the game area (see Figure 1). 152 3. The parts that form a fraction inside a picture do not have to be positioned side-by-side (see Figures 5 and 6) 4. All parts used to form a fraction must be of equal size. 5. The fraction that must be formed on each picture has a numerator greater than or equal to one (see Figures 5 and 6). 6. The fraction that must be formed is selected by the software automatically. 7. Each completed round generates one new version (see Figure 1). The software keeps track of all versions so that players may start discussions and voting processes on any vers10n. 8. Players discuss about the plausibility of the proposed solutions, registering evidence in favor of and against the solutions in the corresponding decision graph. The evidence is expressed in natural language and labeled by the player as evidence in favor of or against a proposed solution. According to the evidence provided and the definitions of the various plausibility states, the software gives feedback about the plausibility of the solutions. 9. Players may start voting processes to solve conflicts that the general discussions did not clear. The voting results are calculated automatically by the software, providing the corresponding feedback to the players about the plausibility of the solutions. I 0. Once the players have ended the discussions and the voting processes, they may request the software to check the proposed solutions automatically. Figure 5: Forming one half. ~E-.1 □ ■ [] ■ ■ CB Figure 6: Forming three quarters. 8 IMPLKMENTATION ISSUES The types of games that have been characterized in this paper are better suited for real-time collaboration because of their inherent dynamics. Players must be able to manipulate and 153 visualize objects concurrently with the best possible response time. We are already developing a set of programming tools for the management of real-time collaboration. The tools are based on the UDP/IP protocol in order to overcome some of the overhead associated with TCP/IP. With respect to plausibility issues, the logic manipulations necessary to provide useful feedback should be transparent to the players. Here, interface and human-machine interaction design decisions will be of primary importance. These facilities are being implemented as a set of programming tools. The implementation of our first prototype will be based primarily on the T .120 standard for real-time collaboration, complemented with the above-mentioned programming tools. The prototype will be able to run on any UDP/IP network, including Internet. 9 CONCLUSIONS The presence of plausibility-driven group decision-making tools in collaborative educational games results in the following advantages: Increased Game Dynamics. Games becoIIJ.e more interesting and challenging for the players because the areas of activity are not limited to the game itself. Better Group Awareness. Plausibility arguments, game rules and frequent player interaction drive players to improve their awareness about the important role that each individual plays in the outcome of the group's performance as a whole. Respect for Different Opinions. The presence of decision-making activities as integral parts of the game promotes each player's recognition that their own opinions are not always common sense for the rest of the group members. Improved Critical Thinking. Plausibility-driven discussions and voting require that the players assume clear positions about their degree of agreement and disagreement on different issues. This implies an increased quality of the thinking process. The collaborative educational games project is now at the application design and development stage in order to produce a working prototype. 10 REFERENCES [Ague87] [CaLe96] [CaZa71] [CiVi66] [DeKr60] Aguero, U. and S. Dasgupta, A "Plausibility-Driven Approach to Computer Arquitecture Design". Communications ofthe ACM, vol 30, no. 11, 1987. Castellon, M. et al. Matematicas 6: texto. Primera Edici6n. San Jose, Costa Rica. Editorial de la Universidad de Costa Rica: PROMECE, Ministerio de Educaci6n Publica, 1996. Cartwright, D. and Zander A. Dinamica de grupos: investigaci6n y teoria. Mexico. Editorial Trillas, 1971. Cirigliano, G. and Villaverde, A. Dina.mica de grupos y educaci6n: fundamentos y tecnicas. Buenos Aires, Argentina. Editorial Hvmanitas, 1966. Deutsch, M. and Krauss, R.M. "Efecto de la amenaza en la negociaci6n interpersonal". Journal ofAbnormal and Social Psychology, no. 61, 1960. 154 Delgado, V. and Valerio, J.O. de. Matematicas 4: texto. Primera Edicion. San Jose, Costa Rica. Editorial de la Universidad de Costa Rica: PROMECE, Ministerio de Educaci6n Publica, 1996. Duran, M., et al. Matematicas 5: texto. Primera Edicion. San Jose, Costa Rica. [DuLe96] Editorial de la Universidad de Costa Rica: PROMECE, Ministerio de Educacion Publica, 1996. Hoffman, L.R. and Kleinman, G.B. "Individual and Group in Group Problem [HoK194] Solving The Valence Model Redressed". Human Communication Research, vol. 21, no. 1, septiembre 1994. [HwMa78] Hwang, C. and Masud, A.S. Lecture Notes in Economics and Mathematical Systems. Multiple Objetive Decision Making. Methods and Applications. A State-of-the-Art Survey. vol. 164, New York, Springer-Verlag, 1978. Janis, LL. Victims ofgroupthinking. Boston, Houghton Mifflin Co., 1972. [Jani72] Johnson, D.W., Maruyama, G., Johnson, R., Nelson, D. and Skon, L. "Efectos [John81] de las estructuras finales de tipo cooperativo, competitivo e individualista en el logro: un meta-analisis". Psychological Bulletin, no. 89, 1981. Martin-Baro, I. Sistema, grupo y poder.. San Salvador, UCA Editores, 1989. [Mart89] Martin-Baro, I. Acci6n e Ideologia. San Salvador, UCA Editores, 1992. [Mart92] Merton, R.K. Teoria y estructuras sociales. Mexico, Fondo de Cultura [Mert80] Economica, 1980. Olivares, C. Fundamentos 16gicos y politicas para un modelo de votaci6n en [Oliv96] grupos grandes basado en la teoria de plausibilidad. Cartago, Tesis para opt r al grado de Magister Scientiae en Computacion en el lnstituto Tecnologico ~ Costa Rica, 1996. Quintero, A.E. iQue me pasa con las matematicas? Algunos factores [Quin89] asociados con la dificultades en el aprendizaje de las matematicas. Editorial de la Universidad de Puerto Rico. 1989. Bulletin of the Special Interest Group for Computer Uses in Education, Special [SIGCU92] Issue on Computer Supported Collaborative Learning, vol.21, no. 3, Spring 1992. [DeVa96] 155 View publication stats