Results for 'relevant modal logic'

993 found
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  1.  36
    The γ-admissibility of Relevant Modal Logics II — The Method using Metavaluations.Takahiro Seki - 2011 - Studia Logica 97 (3):351-383.
    The?-admissibility is one of the most important problems in the realm of relevant logics. To prove the 7-admissibility, either the method of normal models or the method using metavaluations may be employed. The?-admissibility of a wide class of relevant modal logics has been discussed in Part I based on a former method, but the?-admissibility based on metavaluations has not hitherto been fully considered. Sahlqvist axioms are well known as a means of expressing generalized forms of formulas with (...)
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  2.  46
    Halldén Completeness for Relevant Modal Logics.Takahiro Seki - 2015 - Notre Dame Journal of Formal Logic 56 (2):333-350.
    Halldén completeness closely resembles the relevance property. To prove Halldén completeness in terms of Kripke-style semantics, the van Benthem–Humberstone theorem is often used. In relevant modal logics, the Halldén completeness of Meyer–Fuhrmann logics has been obtained using the van Benthem–Humberstone theorem. However, there remain a number of Halldén-incomplete relevant modal logics. This paper discusses the Halldén completeness of a wider class of relevant modal logics, namely, those with some Sahlqvist axioms.
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  3.  47
    Some Metacomplete Relevant Modal Logics.Takahiro Seki - 2013 - Studia Logica 101 (5):1115-1141.
    A logic is called metacomplete if formulas that are true in a certain preferred interpretation of that logic are theorems in its metalogic. In the area of relevant logics, metacompleteness is used to prove primeness, consistency, the admissibility of γ and so on. This paper discusses metacompleteness and its applications to a wider class of modal logics based on contractionless relevant logics and their neighbours using Slaney’s metavaluational technique.
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  4.  78
    General Frames for Relevant Modal Logics.Takahiro Seki - 2003 - Notre Dame Journal of Formal Logic 44 (2):93-109.
    General frames are often used in classical modal logic. Since they are duals of modal algebras, completeness follows automatically as with algebras but the intuitiveness of Kripke frames is also retained. This paper develops basics of general frames for relevant modal logics by showing that they share many important properties with general frames for classical modal logic.
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  5.  57
    An incomplete relevant modal logic.Lou Goble - 2000 - Journal of Philosophical Logic 29 (1):103-119.
    The relevant modal logic G is a simple extension of the logic RT, the relevant counterpart of the familiar classically based system T. Using the Routley-Meyer semantics for relevant modal logics, this paper proves three main results regarding G: (i) G is semantically complete, but only with a non-standard interpretation of necessity. From this, however, other nice properties follow. (ii) With a standard interpretation of necessity, G is semantically incomplete; there is no class (...)
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  6.  51
    A Sahlqvist theorem for relevant modal logics.Takahiro Seki - 2003 - Studia Logica 73 (3):383-411.
    Kripke-completeness of every classical modal logic with Sahlqvist formulas is one of the basic general results on completeness of classical modal logics. This paper shows a Sahlqvist theorem for modal logic over the relevant logic Bin terms of Routley- Meyer semantics. It is shown that usual Sahlqvist theorem for classical modal logics can be obtained as a special case of our theorem.
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  7.  23
    A Sahlqvist Theorem for Relevant Modal Logics.Takahiro Seki - 2003 - Studia Logica 73 (3):383-411.
    Kripke-completeness of every classical modal logic with Sahlqvist formulas is one of the basic general results on completeness of classical modal logics. This paper shows a Sahlqvist theorem for modal logic over the relevant logic Bin terms of Routley-Meyer semantics. It is shown that usual Sahlqvist theorem for classical modal logics can be obtained as a special case of our theorem.
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  8.  28
    The γ-admissibility of Relevant Modal Logics I — The Method of Normal Models.Takahiro Seki - 2011 - Studia Logica 97 (2):199-231.
    The admissibility of Ackermann’s rule γ is one of the most important problems in relevant logic. While the γ-admissibility of normal modal logics based on the relevant logic R has been previously discussed, the case for weaker relevant modal logics has not yet been considered. The method of normal models has often been used to prove the γ-admissibility. This paper discusses which relevant modal logics admit γ from the viewpoint of the (...)
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  9.  38
    An Algebraic Proof of the Admissibility of γ in Relevant Modal Logics.Takahiro Seki - 2012 - Studia Logica 100 (6):1149-1174.
    The admissibility of Ackermann's rule γ is one of the most important problems in relevant logics. The admissibility of γ was first proved by an algebraic method. However, the development of Routley-Meyer semantics and metavaluational techniques makes it possible to prove the admissibility of γ using the method of normal models or the method using metavaluations, and the use of such methods is preferred. This paper discusses an algebraic proof of the admissibility of γ in relevant modal (...)
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  10.  57
    Models for relevant modal logics.André Fuhrmann - 1990 - Studia Logica 49 (4):501 - 514.
    Semantics are given for modal extensions of relevant logics based on the kind of frames introduced in [7]. By means of a simple recipe we may obtain from a class FRM (L) of unreduced frames characterising a (non-modal) logic L, frame-classes FRM (L.M) characterising conjunctively regular modal extensions L.M of L. By displaying an incompleteness phenomenon, it is shown how the recipe fails when reduced frames are under consideration.
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  11.  56
    Boolean negation and non-conservativity I: Relevant modal logics.Tore Fjetland Øgaard - 2021 - Logic Journal of the IGPL 29 (3):340-362.
    Many relevant logics can be conservatively extended by Boolean negation. Mares showed, however, that E is a notable exception. Mares’ proof is by and large a rather involved model-theoretic one. This paper presents a much easier proof-theoretic proof which not only covers E but also generalizes so as to also cover relevant logics with a primitive modal operator added. It is shown that from even very weak relevant logics augmented by a weak K-ish modal operator, (...)
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  12.  92
    Modal logic as metalogic.Kosta Došen - 1992 - Journal of Logic, Language and Information 1 (3):173-201.
    The goal of this paper is to show how modal logic may be conceived as recording the derived rules of a logical system in the system itself. This conception of modal logic was propounded by Dana Scott in the early seventies. Here, similar ideas are pursued in a context less classical than Scott's.First a family of propositional logical systems is considered, which is obtained by gradually adding structural rules to a variant of the nonassociative Lambek calculus. (...)
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  13. Modal Logics A Summary of the Well-Behaved.Melvin Fitting - unknown
    Modal logic is an enormous subject, and so any discussion of it must limit itself according to some set of principles. Modal logic is of interest to mathematicians, philosophers, linguists and computer scientists, for somewhat different reasons. Typically a philosopher may be interested in capturing some aspect of necessary truth, while a mathematician may be interested in characterizing a class of models having special structural features. For a computer scientist there is another criterion that is not (...)
     
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  14.  49
    Canonical modal logics and ultrafilter extensions.J. F. A. K. van Benthem - 1979 - Journal of Symbolic Logic 44 (1):1-8.
    In this paper thecanonicalmodal logics, a kind of complete modal logics introduced in K. Fine [4] and R. I. Goldblatt [5], will be characterized semantically using the concept of anultrafilter extension, an operation on frames inspired by the algebraic theory of modal logic. Theorem 8 of R. I. Goldblatt and S. K. Thomason [6] characterizing the modally definable Σ⊿-elementary classes of frames will follow as a corollary. A second corollary is Theorem 2 of [4] which states that (...)
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  15.  33
    Russell's Modal Logic? Review of Jan Dejnožka, Bertrand Russell on Modality and Logical Relevance.Gary Ostertag - 2000 - Russell: The Journal of Bertrand Russell Studies 20 (2):165-72.
  16.  91
    Axiomatizability of Propositionally Quantified Modal Logics on Relational Frames.Peter Fritz - 2024 - Journal of Symbolic Logic 89 (2):758-793.
    Propositional modal logic over relational frames is naturally extended with propositional quantifiers by letting them range over arbitrary sets of worlds of the relevant frame. This is also known as second-order propositional modal logic. The propositionally quantified modal logic of a class of relational frames is often not axiomatizable, although there are known exceptions, most notably the case of frames validating the strong modal logic $\mathrm {S5}$. Here, we develop new general (...)
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  17. Regression in Modal Logic.Robert Demolombe, Andreas Herzig & Ivan Varzinczak - 2003 - Journal of Applied Non-Classical Logics 13 (2):165-185.
    In this work we propose an encoding of Reiter’s Situation Calculus solution to the frame problem into the framework of a simple multimodal logic of actions. In particular we present the modal counterpart of the regression technique. This gives us a theorem proving method for a relevant fragment of our modal logic.
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  18.  26
    Russell's Modal Logic? [review of Jan Dejnožka, Bertrand Russell on Modality and Logical Relevance ].Gary Ostertag - 2000 - Russell: The Journal of Bertrand Russell Studies 20 (2).
  19.  30
    Neighborhood Semantics for Modal Logic.Eric Pacuit - 2017 - Cham, Switzerland: Springer.
    This book offers a state-of-the-art introduction to the basic techniques and results of neighborhood semantics for modal logic. In addition to presenting the relevant technical background, it highlights both the pitfalls and potential uses of neighborhood models – an interesting class of mathematical structures that were originally introduced to provide a semantics for weak systems of modal logic. In addition, the book discusses a broad range of topics, including standard modal logic results ; (...)
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  20.  32
    The modal logic of Reverse Mathematics.Carl Mummert, Alaeddine Saadaoui & Sean Sovine - 2015 - Archive for Mathematical Logic 54 (3-4):425-437.
    The implication relationship between subsystems in Reverse Mathematics has an underlying logic, which can be used to deduce certain new Reverse Mathematics results from existing ones in a routine way. We use techniques of modal logic to formalize the logic of Reverse Mathematics into a system that we name s-logic. We argue that s-logic captures precisely the “logical” content of the implication and nonimplication relations between subsystems in Reverse Mathematics. We present a sound, complete, (...)
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  21.  37
    On the non-availability of Dawson-modeling into certain relevance alethic modal logics.John Chidgey - 1979 - Studia Logica 38 (2):89 - 94.
    This paper shows that the Dawson technique of modelling deontic logics into alethic modal logics to gain insight into deontic formulas is not available for modelling a normal (in the spirit of Anderson) relevance deontic modal logic into either of the normal relevance alethic modal logics R S4or R M. The technique is to construct an extension of the well known entailment matrix set M 0and show that the model of the deontic formula P (A v (...)
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  22.  38
    Classically complete modal relevant logics.Edwin D. Mares - 1993 - Mathematical Logic Quarterly 39 (1):165-177.
    A variety of modal logics based on the relevant logic R are presented. Models are given for each of these logics and completeness is shown. It is also shown that each of these logics admits Ackermann's rule γ and as a corollary of this it is proved that each logic is a conservative extension of its counterpart based on classical logic, hence we call them “classically complete”. MSC: 03B45, 03B46.
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  23.  17
    Topological Modal Logics Satisfying Finite Chain Conditions.Bernhard Heinemann - 1998 - Notre Dame Journal of Formal Logic 39 (3):406-421.
    We modify the semantics of topological modal logic, a language due to Moss and Parikh. This enables us to study the corresponding theory of further classes of subset spaces. In the paper we deal with spaces where every chain of opens fulfils a certain finiteness condition. We consider both a local finiteness condition relevant to points and a global one concerning the whole frame. Completeness of the appearing logical systems, which turn out to be generalizations of the (...)
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  24.  16
    Constant Domain Quantified Modal Logics Without Boolean Negation.Greg Restall - 2005 - Australasian Journal of Logic 3:45-62.
    his paper provides a sound and complete axiomatisation for constant domain modal logics without Boolean negation. This is a simpler case of the difficult problem of providing a sound and complete axiomatisation for constant-domain quantified relevant logics, which can be seen as a kind of modal logic with a two-place modal operator, the relevant conditional. The completeness proof is adapted from a proof for classical modal predicate logic (I follow James Garson’s 1984 (...)
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  25.  20
    A Short and Readable Proof of Cut Elimination for Two First-Order Modal Logics.Feng Gao & George Tourlakis - 2015 - Bulletin of the Section of Logic 44 (3/4):131-147.
    A well established technique toward developing the proof theory of a Hilbert-style modal logic is to introduce a Gentzen-style equivalent (a Gentzenisation), then develop the proof theory of the latter, and finally transfer the metatheoretical results to the original logic (e.g., [1, 6, 8, 18, 10, 12]). In the first-order modal case, on one hand we know that the Gentzenisation of the straightforward first-order extension of GL, the logic QGL, admits no cut elimination (if the (...)
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  26.  13
    Modal Logic and Its Applications. [REVIEW]T. K. - 1971 - Review of Metaphysics 25 (2):370-371.
    The history of contemporary modal logic dates back to the writings of C. S. Lewis in the early part of this century. Since then, a growing body of literature has attested to professional interest in the area, and in a number of related issues in philosophical logic which have received wide attention. The recent development of powerful formal techniques for modal system building, together with an increasing interest in modal logic as a tool for (...)
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  27.  19
    A General Semantic for Quantified Modal Logic.Robert Goldblatt & Edwin D. Mares - 1998 - In Marcus Kracht, Maarten de Rijke, Heinrich Wansing & Michael Zakharyaschev (eds.), Advances in Modal Logic. CSLI Publications. pp. 227-246.
    In "An Alternative Semantics for Quantified Relevant Logic" (JSL 71 (2006)) we developed a semantics for quantified relevant logic that uses general frames. In this paper, we adapt that model theory to treat quantified modal logics, giving a complete semantics to the quantified extensions, both with and without the Barcan formula, of every proposi- tional modal logic S. If S is canonical our models are based on propositional frames that validate S. We employ (...)
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  28.  37
    Computing with cylindric modal logics and arrow logics, lower Bounds.Maarten Marx - 2002 - Studia Logica 72 (2):233-252.
    The complexity of the satisfiability problems of various arrow logics and cylindric modal logics is determined. As is well known, relativising these logics makes them decidable. There are several parameters that can be set in such a relativisation. We focus on the following three: the number of variables involved, the similarity type and the kind of relativised models considered. The complexity analysis shows the importance and relevance of these parameters.
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  29.  62
    Quantified Modal Relevant Logics.Nicholas Ferenz - 2023 - Review of Symbolic Logic 16 (1):210-240.
    Here, I combine the semantics of Mares and Goldblatt [20] and Seki [29, 30] to develop a semantics for quantified modal relevant logics extending ${\bf B}$. The combination requires demonstrating that the Mares–Goldblatt approach is apt for quantified extensions of ${\bf B}$ and other relevant logics, but no significant bridging principles are needed. The result is a single semantic approach for quantified modal relevant logics. Within this framework, I discuss the requirements a quantified modal (...)
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  30.  34
    St. Thomas’ Modal Logic: Did Wittgenstein and Heidegger Embrace It?Robert C. Trundle Jr - 1996 - Idealistic Studies 26 (1):79-99.
    Wittgenstein and Heidegger were not merely pioneering leaders of different philosophical schools. They both disavowed a Judeo-Christian God and influenced trends opposed to traditional metaphysical arguments. Therefore, we may suppose that they had a major role in relegating medieval arguments for God to archaic syllogistic pedantries. But I will argue that a conditional premise in Thomas’ Second-Way argument not only finds expression in modal logic, since it specifies necessarily if there is no God, there is no world, but (...)
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  31. Modal Logic vs. Ontological Argument.Andrezej Biłat - 2012 - European Journal for Philosophy of Religion 4 (2):179--185.
    The contemporary versions of the ontological argument that originated from Charles Hartshorne are formalized proofs based on unique modal theories. The simplest well-known theory of this kind arises from the b system of modal logic by adding two extra-logical axioms: “If the perfect being exists, then it necessarily exists‘ and “It is possible that the perfect being exists‘. In the paper a similar argument is presented, however none of the systems of modal logic is (...) to it. Its only premises are the axiom and, instead of, the new axiom : “If the perfect being doesn’t exist, it necessarily doesn’t‘. The main goal of the work is to prove that is no more controversial than and -- in consequence -- the whole strength of the modal ontological argument lies in the set of its extra-logical premises. In order to do that, three arguments are formulated: ontological, “cosmological‘ and metalogical. (shrink)
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  32.  40
    A semantical proof of the admissibility of the rule assertion in some relevant and modal logics.Gemma Robles - 2012 - Bulletin of the Section of Logic 41 (1/2):51-60.
  33.  37
    Note on a strong liberated modal logic and its relevance to possible world skepticism.Charles G. Morgan - 1979 - Notre Dame Journal of Formal Logic 20 (4):718-722.
  34.  8
    Interpretations of Weak Positive Modal Logics.Katalin Bimbó - 2021 - In Ofer Arieli & Anna Zamansky (eds.), Arnon Avron on Semantics and Proof Theory of Non-Classical Logics. Springer Verlag. pp. 13-38.
    This paper investigates set-theoretical semantics for logics that contain unary connectives, which can be viewed as modalities. Indeed, some of the logics we consider are closely related to linear logic. We use insights from the relational semantics of relevance logics together with a new version of the squeeze lemma in our semantics for logics with disjunction. The ideal-based semantics, which takes co-theories to be situations, dualizes the theory-based semantics for logics with conjunction.
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  35. Remark on Al-Fārābī's missing modal logic and its effect on Ibn Sīnā.Wilfrid Hodges - 2019 - Eshare: An Iranian Journal of Philosophy 1 (3):39-73.
    We reconstruct as much as we can the part of al-Fārābī's treatment of modal logic that is missing from the surviving pages of his Long Commentary on the Prior Analytics. We use as a basis the quotations from this work in Ibn Sīnā, Ibn Rushd and Maimonides, together with relevant material from al-Fārābī's other writings. We present a case that al-Fārābī's treatment of the dictum de omni had a decisive effect on the development and presentation of Ibn (...)
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  36.  18
    Bertrand Russell on modality and logical relevance.Bernard Linsky - 2015 - [North Charleston, South Carolina]: [CreateSpace].
    BERTRAND RUSSELL ON MODALITY AND LOGICAL RELEVANCE - SECOND EDITION of 2015. Praise for the first edition of 1999: "In the twenty-nine years since Russell's death, much of the major scholarship has drawn heavily on his manuscripts and unpublished correspondence. The author shows that the published Russell is capable of new interpretations; in particular, that modal notions such as possibility have a greater place in various aspects of his logical and philosophical thought than has been previously imagined." -Ivor Grattan-Guinness, (...)
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  37.  55
    Quantifiers, propositions and identity: admissible semantics for quantified modal and substructural logics.Robert Goldblatt - 2011 - New York: Cambridge University Press.
    Many systems of quantified modal logic cannot be characterised by Kripke's well-known possible worlds semantic analysis. This book shows how they can be characterised by a more general 'admissible semantics', using models in which there is a restriction on which sets of worlds count as propositions. This requires a new interpretation of quantifiers that takes into account the admissibility of propositions. The author sheds new light on the celebrated Barcan Formula, whose role becomes that of legitimising the Kripkean (...)
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  38.  6
    Modal translation: the relevance of worlds.Paul Hanmer - 2023 - Wilmington, Delaware: Vernon Press.
    This book concerns the philosophical analysis of modal sentences. David Lewis' Modal Translation Scheme 'translates' sentences of quantified modal logic into sentences of predicate logic supplemented by counterpart theory. A number of theoretical advantages are thereby secured. One component of the translation scheme makes reference to non-actual but possible worlds i.e. the primitive predicate "at a world(s), w". The author addresses the problem of advanced modal sentences which threaten this predicate and so the ability (...)
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  39.  15
    A Substructural Approach to Explicit Modal Logic.Shawn Standefer - 2023 - Journal of Logic, Language and Information 32 (2):333–362.
    In this paper, we build on earlier work by Standefer (Logic J IGPL 27(4):543–569, 2019) in investigating extensions of substructural logics, particularly relevant logics, with the machinery of justification logics. We strengthen a negative result from the earlier work showing a limitation with the canonical model method of proving completeness. We then show how to enrich the language with an additional operator for implicit commitment to circumvent these problems. We then extend the logics with axioms for D, 4, (...)
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  40.  34
    Neighbourhood Semantics for Modal Relevant Logics.Nicholas Ferenz & Andrew Tedder - 2023 - Journal of Philosophical Logic 52 (1):145-181.
    In this paper, we investigate neighbourhood semantics for modal extensions of relevant logics. In particular, we combine the neighbourhood interpretation of the relevant implication (and related connectives) with a neighbourhood interpretation of modal operators. We prove completeness for a range of systems and investigate the relations between neighbourhood models and relational models, setting out a range of augmentation conditions for the various relations and operations.
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  41. Epistemic Closure and Epistemic Logic I: Relevant Alternatives and Subjunctivism.Wesley H. Holliday - 2015 - Journal of Philosophical Logic 44 (1):1-62.
    Epistemic closure has been a central issue in epistemology over the last forty years. According to versions of the relevant alternatives and subjunctivist theories of knowledge, epistemic closure can fail: an agent who knows some propositions can fail to know a logical consequence of those propositions, even if the agent explicitly believes the consequence (having “competently deduced” it from the known propositions). In this sense, the claim that epistemic closure can fail must be distinguished from the fact that agents (...)
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  42.  13
    Relevant Logics.Edwin D. Mares & Robert K. Meyer - 2001 - In Lou Goble (ed.), The Blackwell Guide to Philosophical Logic. Malden, Mass.: Wiley-Blackwell. pp. 280–308.
    Once upon a time, modal logic was castigated because it ‘had no semantics.’ Kripke, Hintikka, Kanger, and others changed all that. In a similar way, when Relevant Logic was introduced by Anderson and Belnap, it too was castigated for ‘having no semantics.’ The present overview marks a culmination of that effort. The semantic approach described here brings together a number of hitherto disparate efforts to set out formal systems for logics of relevant implication and entailment. (...)
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  43.  64
    An Incompleteness Theorem for Modal Relevant Logics.Shawn Standefer - 2021 - Notre Dame Journal of Formal Logic 62 (4):669 - 681.
    In this paper, an incompleteness theorem for modal extensions of relevant logics is proved. The proof uses elementary methods and builds upon the work of Fuhrmann.
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  44.  24
    Non-Boolean classical relevant logics I.Tore Fjetland Øgaard - 2019 - Synthese (8):1-32.
    Relevant logics have traditionally been viewed as paraconsistent. This paper shows that this view of relevant logics is wrong. It does so by showing forth a logic which extends classical logic, yet satisfies the Entailment Theorem as well as the variable sharing property. In addition it has the same S4-type modal feature as the original relevant logic E as well as the same enthymematical deduction theorem. The variable sharing property was only ever regarded (...)
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  45.  14
    Modern Modalities: Studies of the History of Modal Theories From Medieval Nominalism to Logical Positivism.Simo Knuuttila (ed.) - 1988 - Kluwer Academic Publishers.
    The word "modem" in the title of this book refers primarily to post-medieval discussions, but it also hints at those medieval mo dal theories which were considered modem in contradistinction to ancient conceptions and which in different ways influenced philosophical discussions during the early modem period. The me dieval developments are investigated in the opening paper, 'The Foundations of Modality and Conceivability in Descartes and His Predecessors', by Lilli Alanen and Simo Knuuttila. Boethius's works from the early sixth century belonged (...)
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  46.  92
    Modal translations in substructural logics.Kosta Došen - 1992 - Journal of Philosophical Logic 21 (3):283 - 336.
    Substructural logics are logics obtained from a sequent formulation of intuitionistic or classical logic by rejecting some structural rules. The substructural logics considered here are linear logic, relevant logic and BCK logic. It is proved that first-order variants of these logics with an intuitionistic negation can be embedded by modal translations into S4-type extensions of these logics with a classical, involutive, negation. Related embeddings via translations like the double-negation translation are also considered. Embeddings into (...)
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  47.  23
    Carnapian Modal and Epistemic Logic and Arithmetic with Descriptions.Jan Heylen - 2009 - Dissertation, Ku Leuven
    In the first chapter I have introduced Carnapian intensional logic against the background of Frege's and Quine's puzzles. The main body of the dissertation consists of two parts. In the first part I discussed Carnapian modal logic and arithmetic with descriptions. In the second chapter, I have described three Carnapian theories, CCL, CFL, and CNL. All three theories have three things in common. First, they are formulated in languages containing description terms. Second, they contain a system of (...)
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  48.  15
    Temporal modalities in Arabic logic.Nicholas Rescher - 1967 - Dordrecht,: D. Reidel.
    Nicholas Rescher. Schools.” An English translation of these sections of the text is given in Appendix A below. No matter how difficult or boring this material proved for the Muslim schoolmaster, it is of the greatest relevance for our interests.
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  49. Bertrand Russell on Modality and Logical Relevance.Jan Dejnožka - 2001 - Studia Logica 68 (2):289-294.
  50.  26
    Relevant propositional dynamic logic.Andrew Tedder & Marta Bilková - 2022 - Synthese 200 (3):1-42.
    Relevant propositional dynamic logics have been sporadically discussed in the broader context of modal relevant logics, but have not come up for sustained investigation until recently. In this paper, we develop a philosophical motivation for these systems, and present some new results suggested by the proposed motivation. Among these, we’ll show how to adapt some recent work to show that the extensions of relevant logics by the extensional truth constants \ are complete with respect to a (...)
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