Historical/temporal necessities/possibilities, and a logical theory of them in branching time

Fuente: arXiv
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Main Authors: Ju, Fengkui, Zhou, Woxuan
Format: Preprint
Published: 2022
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author Ju, Fengkui
Zhou, Woxuan
author_facet Ju, Fengkui
Zhou, Woxuan
contents In this paper, we do three kinds of work. First, we recognize four notions of necessity and two notions of possibility related to time flow, namely strong/weak historical/temporal necessities, as well as historical/temporal possibilities, which are motivated more from a linguistic perspective than from a philosophical one. Strong/weak historical necessities and historical possibility typically concern the possible futures of the present world, and strong/weak temporal necessities and temporal possibility concern possible timelines of alternatives of the present world. Second, we provide our approach to the six notions and present a logical theory of them in branching time. Our approach to the six notions is as follows. The agent has a system of ontic rules that determine expected timelines. She treats some ontic rules as undefeatable, determining accepted timelines. The domains of strong/weak historical necessities, respectively, consist of accepted and expected timelines passing through the present moment, and historical possibility is the dual of strong historical necessity. The domains of strong/weak temporal necessities, respectively, consist of accepted and expected timelines, and temporal possibility is the dual of strong temporal necessity. The logical theory has six operators: a last-moment operator, a next-moment operator, and four operators for the four notions of necessity. Formulas' evaluation contexts consist of a tree-like model representing a time flow, a context representing the agent's system of ontic rules, a timeline, and an instant. Third, we offer an axiomatic system for the logical theory and show its soundness and completeness.
format Preprint
id arxiv_https___arxiv_org_abs_2208_11922
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Historical/temporal necessities/possibilities, and a logical theory of them in branching time
Ju, Fengkui
Zhou, Woxuan
Computation and Language
In this paper, we do three kinds of work. First, we recognize four notions of necessity and two notions of possibility related to time flow, namely strong/weak historical/temporal necessities, as well as historical/temporal possibilities, which are motivated more from a linguistic perspective than from a philosophical one. Strong/weak historical necessities and historical possibility typically concern the possible futures of the present world, and strong/weak temporal necessities and temporal possibility concern possible timelines of alternatives of the present world. Second, we provide our approach to the six notions and present a logical theory of them in branching time. Our approach to the six notions is as follows. The agent has a system of ontic rules that determine expected timelines. She treats some ontic rules as undefeatable, determining accepted timelines. The domains of strong/weak historical necessities, respectively, consist of accepted and expected timelines passing through the present moment, and historical possibility is the dual of strong historical necessity. The domains of strong/weak temporal necessities, respectively, consist of accepted and expected timelines, and temporal possibility is the dual of strong temporal necessity. The logical theory has six operators: a last-moment operator, a next-moment operator, and four operators for the four notions of necessity. Formulas' evaluation contexts consist of a tree-like model representing a time flow, a context representing the agent's system of ontic rules, a timeline, and an instant. Third, we offer an axiomatic system for the logical theory and show its soundness and completeness.
title Historical/temporal necessities/possibilities, and a logical theory of them in branching time
topic Computation and Language
url https://arxiv.org/abs/2208.11922