An encompassing framework for Paraconsistent Logic Programs

We propose a framework which extends Antitonic Logic Programs [Damásio and Pereira, in: Proc. 6th Int. Conf. on Logic Programming and Nonmonotonic Reasoning, Springer, 2001, p. 748] to an arbitrary complete bilattice of truth-values, where belief and doubt are explicitly represented. Inspired by Ginsberg and Fitting's bilattice approaches, this framework allows a precise definition of important operators found in logic programming, such as explicit and default negation. In particular, it leads to a natural semantical integration of explicit and default negation through the Coherence Principle [Pereira and Alferes, in: European Conference on Artificial Intelligence, 1992, p. 102], according to which explicit negation entails default negation. We then define Coherent Answer Sets, and the Paraconsistent Well-founded Model semantics, generalizing many paraconsistent semantics for logic programs. In particular, Paraconsistent Well-Founded Semantics with eXplicit negation (WFSX_p) [Alferes et al., J. Automated Reas. 14 (1) (1995) 93–147; Damásio, PhD thesis, 1996]. The framework is an extension of Antitonic Logic Programs for most cases, and is general enough to capture Probabilistic Deductive Databases, Possibilistic Logic Programming, Hybrid Probabilistic Logic Programs, and Fuzzy Logic Programming. Thus, we have a powerful mathematical formalism for dealing simultaneously with default, paraconsistency, and uncertainty reasoning. Results are provided about how our semantical framework deals with inconsistent information and with its propagation by the rules of the program.     

Contents of Volume 138

Volume Contents

Contents of Volume 138     

Stem cell research in a Catholic institution: yes or no?

Catholic teaching has no moral difficulties with research on stem cells derived from adult stem cells or fetal cord blood. The ethical problem comes with embryonic stem cells since their genesis involves the destruction of a human embryo. However, there seems to be significant promise of health benefits from such research. Although Catholic teaching does not permit any destruction of human embryos, the question remains whether researchers in a Catholic institution, or any researchers opposed to destruction of human embryos, could participate in research on cultured embryonic stem cells, or whether a Catholic institution could use any therapy that ultimately results from such research. This position paper examines how such research could be conducted legitimately in a Catholic institution by using an ethical analysis involving a narrative context, the nature of the moral act, and the principle of material cooperation, along with references to significant ethical assessments. It also offers tentative guidelines that could be used by a Catholic institution in implementing such research.     

The role of fair treatment and rewards in perceptions of organizational support and leader-member exchange

This study examined a model of the antecedents and consequences of perceived organizational support (POS) and leader-member exchange (LMX). It was predicted that organizational justice (procedural and distributive justice) and organizational practices that provide recognition to the employee (feelings of inclusion and recognition from upper management) would influence POS. For LMX, it was predicted that leader reward (distributive justice and contingent rewards) and punishment behavior would be important antecedents. Results based on a sample of 211 employee-supervisor dyads indicated that organizational justice, inclusion, and recognition were related to POS and contingent rewards were related to LMX. In terms of consequences, POS was related to employee commitment and organizational citizenship behavior, whereas LMX predicted performance ratings.     

Implications of Racial Diversity in the Supervisor-Subordinate Relationship

This study addresses the impact of race on the supervisor-subordinate relationship. The purpose is to examine this relationship with minority subordinates reporting to both majority and minority group members. Using the subordinates needs framework identified by Baird and Kram (1983), 5 areas were addressed: supervisory support, developmental opportunities, procedural justice, acceptance or assimilation, and discrimination. The results indicated that African American subordinates with White supervisors experience less supervisory support, developmental opportunities, procedural justice, assimilation, and more discrimination than African American subordinates with African American supervisors.     

The Effects of Competition on the Decision Quality of Diverse and Nondiverse Groups

Research has validated that intragroup cooperation, rather than competition, produces more positive group interaction and interpersonal acceptance which leads to better performance. The unique values of culturally diverse group members, however, may influence group processes and performance if these group members respond differently to situational cues. Research on the interaction between cultural diversity and competitive team situations would benefit organizations that employ an increasingly diverse work force. The primary purpose of this study is to explore the effects of cultural diversity on group performance and group processes by comparing culturally diverse and culturally nondiverse groups under conditions of intergroup competition and noncompetition. This experiment was conducted using 500 upper-level undergraduate students enrolled in a principles of management course at a large university in the southwestern United States. The results of this experiment indicate that the competitive nondiverse groups performed better than did the noncompetitive diverse groups in terms of quality of performance. Results also suggest that both the culturally diverse and culturally nondiverse groups outperformed their best individual members' scores when they were matched with competitive situations that enhanced their innate group processing styles. Organizations can increase their effectiveness by appreciating that diverse and nondiverse groups respond differently under conditions of competition and noncompetition.     

Personal Characteristics,Job Performance,and Absenteeism of Public School Teachers1

Personal characteristics and job performance were examined as potential predictors of absenteeism for a professional occupational group. Data on 152 public school teachers demonstrated that sex and independence contributed unique variance to the prediction of absenteeism. Furthermore, the interaction terms of sex with independence, with the ability to control anxiety, and with performance rating significantly added to the variance explained in absenteeism. Implications of the present results are discussed as well as suggestions for future research.     

Relational frameworks for recall in young and older adults

Recent research indicates the presence of an age-related visual processing deficit, for which the elderly may attempt to compensate through the use of relational information. This hypothesis was tested, using the category superiority effect as a model system. In studies of young adults, the category superiority effect has been shown to be confined to relatively abstract stimulus materials, such as verbal items, and to be absent for pictures. However, it was predicted that a category superiority effect would be present in elderly adults both for verbal and for pictorial stimuli, since the elderly would be expected to utilize category information to compensate for imagerie deficits. This prediction was confirmed, consistent with the hypothesis advanced above. It was further suggested that the establishment of a prior framework for recall, based on relational information, would reduce this effect significantly. This prediction was also confirmed. This research was supported by Grant AGI 1605, National Institute on Aging, and by a grant from the School of Natural Sciences, California State University, Fresno.     

Self-esteem,evaluative feedback,and preacquaintance attraction: Indirect reactions to success and failure

Two experiments were conducted to investigate the indirect reactions of high-and low-self-esteem persons to evaluative feedback. Indirect reactions are defined as reactions to evaluative feedback directed toward individuals or mechanisms not associated with the feedback. In each experiment, a sample of college students divided according to level of dispositional self-esteem was provided with feedback on a bogus test of social intelligence. Subjects were informed that each of them had been paired randomly with another person in the session and would interact with that person later in the session. Prior to meeting the individual with whom each ostensibly had been paired, subjects indicated their evaluation of and attraction to those persons. In both experiments a cross-over pattern emerged due to greater attraction following success vs. failure feedback among low-self-esteem subjects and greater attraction following failure vs. success feedback among high-self-esteem subjects. This finding indicates an important new class of reactions to evaluative feedback, indirect reactions, that extends beyond the immediate context in which the feedback is received.Preparation of this article was facilitated by a Summer Faculty Research Fellowship to Rick H. Hoyle from the Office of the Vice President for Research and Graduate Studies at the University of Kentucky.This article is based, in part, on a Master's thesis conducted by Rick H. Hoyle under the supervision of Chester A. Insko. We thank Tom Pyszczynski and John Schopler for helpful advice on the design of the second experiment and Charles Carlson and Monica Harris for helpful comments on a draft of the article.Portions of the research reported in this article were presented at the 94th Annual Convention of the American Psychological Association, Washington, DC, 1986; the 58th Annual Meeting of the Eastern Psychological Association, Arlington, Va, 1987; and the 62nd Annual Meeting of the Eastern Psychological Association, New York, NY, 1991.