Explicit Logic Research Articles

On the models for asynchronous circuit behaviour with OR causality

Asynchronous circuits behave like concurrent programs implemented in hardware logic. The processes in such circuits are synchronised in accordance with the dynamic logical and causal conditions between switching events. The classical paradigm, easily represented in most process-oriented languages for concurrent systems modelling, is AND causality, which is often associated with a rendez-vous synchronisation. In this paper we investigate a different, less known paradigm, called OR causality. This paradigm is however different from the classical MERGE paradigm, which is based on mutually exclusive events. Petri nets and Change Diagrams provide adequate modelling and circuit synthesis tools for the various OR causality types, yet they do not always bring the specifier to a unique decision about which modelling construct must be used for which type. We present a unified descriptive tool, called Causal Logic Net, which is graphically based on Petri net but has an explicit logic causality annotation for transitions. It is aimed as the least possible generalisation of Petri nets and Change Diagrams. The signal-transition interpretation of this tool is analogous to, but more powerful than, the well-known Signal Transition Graph. A number of examples demonstrate the usefulness of this model in the synthesis of asynchronous control circuits. It is shown that the extension of the basic, unconditional, firing rule with the one that depends upon the marking of the transition preconditions increases the descriptive power of the model to that of the Turing Machine model and allows the modelling of non-commutative state transition behaviour in a purely causal form.

Logic for dialogue games

The purpose of this paper is to work toward an explicit logic and semantics for a game theoretically inspired theory of action. The purpose of the logic is to explicate the conceptual machinery implicit in the dialogue-game model of rational discourse developed in Carlson (1983). A variety of ideas and techniques of modal and philosophical logic are used to define a model structure that generalizes the game theoretical notion of a game in extensive form (von Neumann and Morgenstern, 1944). Relative to this model structure, semantic characterizations are given to the action-theoretic notions oftime, possibility, belief, preference, ability, intention, action, andrationality. The unification of these characterizations under the game-theoretical paradigm leads to insights about the logical interdependences between these concepts. The resulting theory of rational interaction is applied to the explication of rational dialogue. The main benefit of the enterprise for a theory of rational dialogue is that concepts and results of game theory become accessible to the explication of dialogue. In particular, the task of proving the logical coherence of a discourse is reduced to the task of showing the rationality of strategy choices made in an associated dialogue game.

The Sentiment of Pragmatism

The Sentiment of Pragmatism

A Hennigian approach to bryophyte phylogeny

Recent empirical advances in bryophyte systematics have been made in the discovery and detailed study of new characters. However, theoretical considerations have not kept pace. Proper attention has not been paid to how these new characters can be used to discover relationships among groups and produce classifications. Recent cladistic studies of the relationships of the major groups of bryophytes have demonstrated the feasibility and usefulness of an approach to phylogenetic systematics derived from the works of Hennig. A Hennigian approach attempts to find the particular hierarchical level at which a given character is a homology (i.e. a synapomorphy or shared, derived character), relationships are established by searching for congruent patterns of homologies, and the resulting hierarchical scheme is used as the basis for a classification. Such an approach provides a rigorous and explicit logic for investigating phylogeny and recognizing natural, historically discrete taxa. The theoretical advantages of a Hennigian approach are discussed and illustrated by examining the congruence of new characters data with preliminary cladograms of the major bryophyte groups.

The overburdened manager and decision making

This article discusses three methods managers can use to make decisions: intuition, management analysis, and Type 1 and Type 2 error analysis. Olson identifies studies that have shown that top managers work at an unrelenting pace and jump from one activity to another. He claims that managers do not have time to plan in a reflective, systematic manner. In fact, in his view, decision makers usually react intuitively to situations that can no longer be ignored. The author presents evidence that top managers prefer verbal media such as telephone calls and meeting for decision making because of their timeliness. He points out that the strategic data bank of the organization is largely in the mind of the manager. As a consequence, he states, an effective analysis requires that the manager communicate to the analyst the relevant data stored in his head. This process often makes it easier for the manager to solve the problem himself rather than delegate it to others. Olson identifies five organizational conditions that enable a top manager to effectively delegate problem solving tasks to management analysts: (1) the analyst must have the confidence of the same people who influence the manager; (2) the analyst must be able to adapt the techniques to the specific needs of the manager; (3) there must be sufficient time for the analyst to structure the problem and evaluate the alternatives; (4) the analyst must share in information gathered by the manager from verbal contacts; and (5) the manager must be part of an organization large enough to make it profitable for him to seek assistance from an analyst. When the above organizational conditions are not met, the author suggests Type 1 and Type 2 error analysis. He promotes this form of analysis as a method for using logic and intuition to consider various forms of information. This management tool is named for Type 1 error (accepting a proposal that should have been rejected) and Type 2 error (rejecting a proposal that should have been accepted). The author advocates the use of this methodology because, in his view, it focuses the attention of the manager on the facts when a decision needs to be made. In this process, the manager must identify and evaluate the likelihood and consequences of each alternative strategy. Olson sees Type 1 and Type 2 error analysis as providing explicit logic to strengthen the intuitive decision making process.

The Scanlon Plan: Co-Operation Through Participation

THE most important task confronting industrial organization is undoubtedly that of securing the active co-operation of its members. It is interesting to note that the earliest economic organizations-simple agricultural and pastoral communities could almost take for granted such co-operation.' These communities rarely had to consider the provision of special incentives: the necessity for belonging to some organized effort which would provide individuals with the means of physical survival was sufficient. It is only with the development of complex industrial society that it has become necessary to recognize that co-operation is a problem that must be solved explicitly. If one were to set out to write about present-day methods for securing cooperation in industrial organizations, it would rapidly become apparent that he was writing primarily about wage-incentive systems. Although it would be easy to accumulate technical details concerning the description of such systems, it would be much more difficult to define any explicit logic for evaluating what makes for a good incentive system. The major evaluative yardstick would appear to be empirical in nature: a good incentive system is one that works. Alternatively, an incentive plan which does not 'incent' is not incentive plan.2 In this article there is suggested alternative method for evaluation in terms of the relationship of such a system to the total functioning of the organization concerned. This point of view focuses attention on three interlocking sets of requirements: productive efficiency, individual satisfaction, and organizational change. Perhaps the selection of these sets of requirements can be clarified by the following comments about the nature of industrial organizations. The existence of any industrial organization depends in part upon the physical resources and the store of technologically relevant knowledge that it possesses. This existence depends also upon the ability of the organization to coordinate the activities of all its members in terms of that knowledge. Considerations such as these focus primarily on the ability of the organization to produce; they assume that any organization can be defined in terms of objective-goods to be produced and they attempt to interpret each aspect * Department of Psychology, Tufts College. The material used in this article is based upon the experience of the author (while a graduate student at the Massachusetts Institute of Technology) in working with Mr. Scanlon. This association covered the period 1947-50, during which time Mr. Scanlon was collaborating with several companies in the development of this incentive system and particularly with the Lapointe Machine Tool Co., Hudson, Mass., and the Market Forge Co., Everett, Mass.