An observation concerning porte's rule in modal logic

Rohan French, Ian Lloyd Humberstone

Research output: Contribution to journalArticleResearchpeer-review

2 Citations (Scopus)

Abstract

It is well known that no consistent normal modal logic contains (as theorems) both ♦A and ♦A (for any formula A). Here we observe that this claim can be strengthened to the following: for any formula A, either no consistent normal modal logic contains ♦ A, or else no consistent normal modal logic contains ♦-A.
Original languageEnglish
Pages (from-to)25 - 31
Number of pages7
JournalBulletin of the Section of Logic
Volume44
Issue number1-2
Publication statusPublished - 2015

Cite this