Modal operator

About: Modal operator is a research topic. Over the lifetime, 1151 publications have been published within this topic receiving 22865 citations. The topic is also known as: modal connective.

Asynchronous Announcements in a Public Channel

Abstract: We propose a variant of public announcement logic for asynchronous systems. We give a syntax where sending and receiving messages are modeled by different modal operators. The natural approach to defining the semantics leads to a circular definition, but we describe two restricted cases in which we solve this problem. The first case requires the Kripke model representing the initial epistemic situation to be a finite tree, and the second one only allows announcements from the existential fragment. Finally, we provide complexity results for the model checking problem.

Reasoning about knowledge in distributed systems using datalog

Abstract: Logic programming has been considered a viable solution for distributed computing since the Fifth Generation Computer Systems project [8]. Nowadays, this line of thought is gaining new verve, pushed by the need for new programming paradigms for addressing new emerging issues in distributed computing. We argue that a missing piece in the current state-of-the-art is the capability to express statements about the knowledge state of distributed nodes. In fact, reasoning about the knowledge state of (group of) nodes has been demonstrated to be fundamental in order to design and analyze distributed protocols [7]. To reach this goal, we designed Knowlog: Datalog¬ augmented with a set of epistemic modal operators, allowing the programmer to directly express what a node "knows" instead of low level communication details.

Modality and interrupts

Abstract: We suggest that modal operators, in addition to their well-understood semantic role in declarative systems, also mark points at which these systems can be interrupted. We use this idea to describe an interruptible declarative system that gradually refines its responses to queries. Although initial responses may be in error, a correct answer will be provided if arbitrarily large computational resources are available. The ideas presented generalize existing work on stratification of logic programs and the treatment of floundered subgoals.

Modal Platonism: an Easy Way to Avoid Ontological Commitment to Abstract Entities

Abstract: Modal Platonism utilizes “weak” logical possibility, such that it is logically possible there are abstract entities, and logically possible there are none. Modal Platonism also utilizes a non-indexical actuality operator.

A Duplication and Loop Checking Free System for S4

Abstract: Most of the sequent/tableau based proof systems for the modal logic S4 need to duplicate formulas and thus are required to adopt some method of loop checking. In what follows we present a tableau-like proof system for S4, based on D'Agostino and Mondadori's classical KE, which is free of duplication and loop checking. The key feature of this system (let us call it KES4) consists in its use of (i) a label formalism which models the semantics of the modal operators according to the usual conditions for S4; and (ii) a label unification scheme which tells us when two labels "denote" the same world in the S4-model(s) generated in the course of proof search. Moreover, it uses special closure conditions to check models for putative contradictions.