Movatterモバイル変換


[0]ホーム

URL:


PhilPapersPhilPeoplePhilArchivePhilEventsPhilJobs
Switch to: References

Add citations

You mustlogin to add citations.
  1. Hereditarily Structurally Complete Intermediate Logics: Citkin’s Theorem Via Duality.Nick Bezhanishvili &Tommaso Moraschini -2023 -Studia Logica 111 (2):147-186.
    A deductive system is said to be structurally complete if its admissible rules are derivable. In addition, it is called hereditarily structurally complete if all its extensions are structurally complete. Citkin (1978) proved that an intermediate logic is hereditarily structurally complete if and only if the variety of Heyting algebras associated with it omits five finite algebras. Despite its importance in the theory of admissible rules, a direct proof of Citkin’s theorem is not widely accessible. In this paper we offer (...) a self-contained proof of Citkin’s theorem, based on Esakia duality and the method of subframe formulas. As a corollary, we obtain a short proof of Citkin’s 2019 characterization of hereditarily structurally complete positive logics. (shrink)
    Direct download(3 more)  
     
    Export citation  
     
    Bookmark   1 citation  
  • Hereditarily Structurally Complete Superintuitionistic Deductive Systems.Alex Citkin -2018 -Studia Logica 106 (4):827-856.
    Propositional logic is understood as a set of theorems defined by a deductive system: a set of axioms and a set of rules. Superintuitionistic logic is a logic extending intuitionistic propositional logic \. A rule is admissible for a logic if any substitution that makes each premise a theorem, makes the conclusion a theorem too. A deductive system \ is structurally complete if any rule admissible for the logic defined by \ is derivable in \. It is known that any (...) logic can be defined by a structurally complete deductive system—its structural completion. The main goal of the paper is to study the following problem: given a superintuitionistic logic L, is the structural completion of L hereditarily structurally complete? It is shown that, on the one hand, there is continuum many of such logics, including \, and many of its standard extensions. On the other hand, there is continuum many superintutitionistic logics structural completion of which is not hereditarily structurally complete. It is observed that the class of hereditarily structurally complete superintuitionistic consequence relations does not have the smallest element and it contains continuum many members lacking the finite model property. The following statement is instrumental in obtaining negative results: if a Lindenbaum algebra of formulas on one variable is finite and has more than 15 elements, then a structural completion of such a logic is not hereditarily structurally complete. (shrink)
    Direct download(4 more)  
     
    Export citation  
     
    Bookmark   2 citations  
  • Locally Tabular $$ne $$ Locally Finite.Sérgio Marcelino &Umberto Rivieccio -2017 -Logica Universalis 11 (3):383-400.
    We show that for an arbitrary logic being locally tabular is a strictly weaker property than being locally finite. We describe our hunt for a logic that allows us to separate the two properties, revealing weaker and weaker conditions under which they must coincide, and showing how they are intertwined. We single out several classes of logics where the two notions coincide, including logics that are determined by a finite set of finite matrices, selfextensional logics, algebraizable and equivalential logics. Furthermore, (...) we identify a closure property on models of a logic that, in the presence of local tabularity, is equivalent to local finiteness. (shrink)
    Direct download(2 more)  
     
    Export citation  
     
    Bookmark   1 citation  

  • [8]ページ先頭

    ©2009-2025 Movatter.jp