Article

Active logic semantics for a single agent in a static world

Institute for Advanced Computer Studies, University of Maryland, College Park, MD 20742, USA; Department of Computer Science, University of Maryland, College Park, MD 20742, USA; Department of Mathematics, Towson University, Towson, MD 21252, USA; Department of Psychology, Franklin & Marshall College, Lancaster, PA 17604, USA; Department of Computer and Systems Engineering, Alexandria University, Alexandria, Egypt
Artificial Intelligence 05/2008; DOI: 10.1016/j.artint.2007.11.005

ABSTRACT For some time we have been developing, and have had significant practical success with, a time-sensitive, contradiction-tolerant logical reasoning engine called the active logic machine (ALMA). The current paper details a semantics for a general version of the underlying logical formalism, active logic. Central to active logic are special rules controlling the inheritance of beliefs in general (and of beliefs about the current time in particular), very tight controls on what can be derived from direct contradictions (P&¬P), and mechanisms allowing an agent to represent and reason about its own beliefs and past reasoning. Furthermore, inspired by the notion that until an agent notices that a set of beliefs is contradictory, that set seems consistent (and the agent therefore reasons with it as if it were consistent), we introduce an “apperception function” that represents an agent's limited awareness of its own beliefs, and serves to modify inconsistent belief sets so as to yield consistent sets. Using these ideas, we introduce a new definition of logical consequence in the context of active logic, as well as a new definition of soundness such that, when reasoning with consistent premises, all classically sound rules remain sound in our new sense. However, not everything that is classically sound remains sound in our sense, for by classical definitions, all rules with contradictory premises are vacuously sound, whereas in active logic not everything follows from a contradiction.

0 Bookmarks
 · 
60 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A formalism for reasoning about actions is proposed that is based on a temporal logic. It allows a much wider range of actions to be described than with previous approaches such as the situation calculus. This formalism is then used to characterize the different types of events, processes, actions, and properties that can be described in simple English sentences. In addressing this problem, we consider actions that involve non-activity as well as actions that can only be defined in terms of the beliefs and intentions of the actors. Finally, a framework for planning in a dynamic world with external events and multiple agents is suggested.
    Artif. Intell. 01/1984; 23:123-154.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Reasoning with limited computational resources (such as time or memory) is an important problem, in particular in knowledge-intensive embedded systems. Classical logic is usually considered inappropriate for this purpose as no guarantees regarding deadlines can be made. One of the more interesting approaches to address this problem is built around the concept of active logics. Although a step in the right direction, active logics are just a preliminary attempt towards nding an acceptable solution. Our work is based on the assumption that Labeled Deductive Sys- tems oer appropriate metamathematical methodology to study the problem. As a rst step, we have reformulated a pair of active logics systems, namely the memory model and its formalized simplication, the step logic, as Labeled Deductive Systems. This paper presents our motivation behind this project, followed by an overview of the investigations on meta-reasoning relevant to this work, and introduces in some reasonable detail the MM system.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents and discusses several methods for reasoning from inconsistent knowledge bases. A so-called argued consequence relation, taking into account the existence of consistent arguments in favour of a conclusion and the absence of consistent arguments in favour of its contrary, is particularly investigated. Flat knowledge bases, i.e., without any priority between their elements, are studied under different inconsistency-tolerant consequence relations, namely the so-called argumentative, free, universal, existential, cardinality-based, and paraconsistent consequence relations. The syntax-sensitivity of these consequence relations is studied. A companion paper is devoted to the case where priorities exist between the pieces of information in the knowledge base. Key words: inconsistency, argumentation, nonmonotonic reasoning, syntaxsensitivity. * Some of the results contained in this paper were presented at the Ninth Conference on Uncertainty in Artificial Intelligence (UAI'...
    Studia Logica 07/1997; · 0.34 Impact Factor

Full-text (2 Sources)

View
11 Downloads
Available from
May 30, 2014