Abstract.ΠMTL is a schematic extension of the monoidal t-norm based logic (MTL) by the characteristic axioms of product logic. In this paper we prove that ΠMTL satisfies the standard completeness theorem. From the algebraic point of view, we show that the class of ΠMTL-algebras (bounded commutative cancellative residuated l-monoids) in the real unit interval [0,1] generates the variety of all ΠMTL-algebras.

In the present paper we show that any at most countable linearly-ordered commutative residuated lattice can be embedded into a commutative residuated lattice on the real unit interval [0, 1]. We use this result to show that Esteva and Godo''s logic MTL is complete with respect to interpretations into commutative residuated lattices on [0, 1]. This solves an open problem raised in.

The present paper deals with the predicate version MTL of the logic MTL by Esteva and Godo. We introduce a Kripke semantics for it, along the lines of Ono''s Kripke semantics for the predicate version of FLew (cf. [O85]), and we prove a completeness theorem. Then we prove that every predicate logic between MTL and classical predicate logic is undecidable. Finally, we prove that MTL is complete with respect to the standard semantics, i.e., with respect to Kripke frames (...) on the real interval [0,1], or equivalently, with respect to MTL-algebras whose lattice reduct is [0,1] with the usual order. (shrink)

The completeness of quantum mechanics is generally interpreted to be or entail the following conditional statement ): If a QM system S is in a pure non-eigenstate of observable A, then S does not have value ak of A at t. QM itself can be assumed to contain two elements: a formula generating probabilities; Hamiltonians that can be time-dependent due to a time-dependent external potential. It is shown that, given and, QM and SC are incompatible. Hence, SC is not (...) the appropriate interpretation of the completeness of QM. (shrink)

An algebraic proof is presented for the finite strong standard completeness of the Involutive Uninorm Logic with Fixed Point ($${{\mathbf {IUL}}^{fp}}$$ IUL fp ). It may provide a first step towards settling the standard completeness problem for the Involutive Uninorm Logic ($${\mathbf {IUL}}$$ IUL, posed in G. Metcalfe, F. Montagna. (J Symb Log 72:834–864, 2007)) in an algebraic manner. The result is proved via an embedding theorem which is based on the structural description of the class (...) of odd involutive FL$$_e$$ e -chains which have finitely many positive idempotent elements. (shrink)

The monoidal t-norm based logic MTL is obtained from Hájek''s Basic Fuzzy logic BL by dropping the divisibility condition for the strong (or monoidal) conjunction. Recently, Jenei and Montgana have shown MTL to be standard complete, i.e. complete with respect to the class of residuated lattices in the real unit interval [0,1] defined by left-continuous t-norms and their residua. Its corresponding algebraic semantics is given by pre-linear residuated lattices. In this paper we address the issue of standard and (...) rational completeness (rational completeness meaning completeness with respect to a class of algebras in the rational unit interval [0,1]) of some important axiomatic extensions of MTL corresponding to well-known parallel extensions of BL. Moreover, we investigate varieties of MTL algebras whose linearly ordered countable algebras embed into algebras whose lattice reduct is the real and/or the rational interval [0,1]. These embedding properties are used to investigate finite strong standard and/or rational completeness of the corresponding logics. (shrink)

Standard conditionals $\varphi > \psi$, by which I roughly mean variably strict conditionals à la Stalnaker and Lewis, are trivially true for impossible antecedents. This article investigates three modifications in a doxastic setting. For the neutral conditional, all impossible-antecedent conditionals are false, for the doxastic conditional they are only true if the consequent is absolutely necessary, and for the metaphysical conditional only if the consequent is ‘model-implied’ by the antecedent. I motivate these conditionals logically, and also doxastically by properties (...) of conditional belief and belief revision. For this I show that the Lewisian hierarchy of conditional logics can be reproduced within ranking semantics, provided we slightly stretch the notion of a ranking function. Given this, acceptance of a conditional can be interpreted as a conditional belief. The epistemic and the neutral conditional deviate from Lewis’ weakest system $V$, in that ID or even CN are dropped, and new axioms appear. The logic of the metaphysical conditional is completely axiomatised by $V$ to which we add the known Kripke axioms T5 for the outer modality. Related completeness results for variations of the ranking semantics are obtained as corollaries. (shrink)

This paper investigates different modes of organizing for corporate social responsibility (CSR). Based on insights from organization theory, we theorize two ways to organize for CSR. “Complete” organization for CSR happens within businesses and depends on the availability of certain organizational elements (e.g., membership, hierarchy, rules, monitoring, and sanctioning). By contrast, “partial” organization for CSR happens when organizers do not have direct access to all these organizational elements. We discuss partial organization for CSR by analyzing how standards and cross-sector partnerships (...) make selective use of organizational elements. We maintain that an important feature of the increasing institutionalization of CSR—not only within businesses but also among non-governmental, governmental, and professional actors—is the rise of partial forms of organization. We discuss the contributions to this Special Issue in the context of our theorization of complete/partial organization for CSR and outline avenues for further research. (shrink)

We prove completeness of the propositional modal logic S 4 for the measure algebra based on the Lebesgue-measurable subsets of the unit interval, [0, 1]. In recent talks, Dana Scott introduced a new measure-based semantics for the standard propositional modal language with Boolean connectives and necessity and possibility operators, and . Propositional modal formulae are assigned to Lebesgue-measurable subsets of the real interval [0, 1], modulo sets of measure zero. Equivalence classes of Lebesgue-measurable subsets form a measure algebra, (...) , and we add to this a non-trivial interior operator constructed from the frame of ‘open’ elements—elements in with an open representative. We prove completeness of the modal logic S 4 for the algebra . A corollary to the main result is that non-theorems of S 4 can be falsified at each point in a subset of the real interval [0, 1] of measure arbitrarily close to 1. A second corollary is that Intuitionistic propositional logic (IPC) is complete for the frame of open elements in. (shrink)

We investigate a lattice of conditional logics described by a Kripke type semantics, which was suggested by Chellas and Segerberg – Chellas–Segerberg (CS) semantics – plus 30 further principles. We (i) present a non-trivial frame-based completeness result, (ii) a translation procedure which gives one corresponding trivial frame conditions for arbitrary formula schemata, and (iii) non-trivial frame conditions in CS semantics which correspond to the 30 principles.

A completeness theorem is established for logics with congruence endowed with general semantics (in the style of general frames). As a corollary, completeness is shown to be preserved by fibring logics with congruence provided that congruence is retained in the resulting logic. The class of logics with equivalence is shown to be closed under fibring and to be included in the class of logics with congruence. Thus, completeness is shown to be preserved by fibring logics with equivalence (...) and general semantics. An example is provided showing that completeness is not always preserved by fibring ligics endowed with standard (non general) semantics. A categorial characterization of fibring is provided using coproducts and cocartesian liftings. (shrink)

The paper first proves the completeness of the first-order predicate logic presented in Carnap’s 1946 article ‘Modalities and quantification’. By contrast the modal logic defined by the semantics Carnap produces is unaxiomatisable. One can though adapt Carnap’s semantics so that a standard completeness proof for a Carnapian version of predicate S5 turns out to be available. //.

We show that, if a suitable intuitionistic metatheory proves that consistency implies satisfiability for subfinite sets of propositional formulas relative either to standard structures or to Kripke models, then that metatheory also proves every negative instance of every classical propositional tautology. Since reasonable intuitionistic set theories such as HAS or IZF do not demonstrate all such negative instances, these theories cannot prove completeness for intuitionistic propositional logic in the present sense.

Kripke completeness of some infinitary predicate modal logics is presented. More precisely, we prove that if a normal modal logic above is -persistent and universal, the infinitary and predicate extension of with BF and BF is Kripke complete, where BF and BF denote the formulas pi pi and x x, respectively. The results include the completeness of extensions of standard modal logics such as , and its extensions by the schemata T, B, 4, 5, D, and their (...) combinations. The proof is obtained by extending the correspondence between the representation of modal algebras and the completeness of propositional modal logic to infinite. (shrink)

There is a standard way of interpreting physicalism. This is as a completeness thesis of some kind. Completeness physicalists believe there is or in principle could be some future physics that provides a complete explanatory or ontological basis for our universe. And this provides a sense in which physics is special among the sciences, the sense in which it is fundamental. This paper contrasts this standard completeness physicalism with what is a more plausible maximality physicalism. (...) Maximality physicalists believe physics is special only in its providing an epistemic framework that is ontologically or explanatorily superior in some respect. This paper shows how completeness physicalists cannot, while maximality physicalists can, provide an adequate explanation of the empirical support for and the pragmatic usefulness of physicalism. It also shows how maximality physicalism is better supported in light of several developments from late twentieth century philosophy of science. (shrink)

The Oxford Translation of Aristotle was originally published in 12 volumes between 1912 and 1954. It is universally recognized as the standard English version of Aristotle. This revised edition contains the substance of the original Translation, slightly emended in light of recent scholarship three of the original versions have been replaced by new translations and a new and enlarged selection of Fragments has been added. The aim of the translation remains the same: to make the surviving works of Aristotle (...) readily accessible to English speaking readers. (shrink)

In standard quantum mechanics, a state vector \ may belong to infinitely many different orthogonal bases, as soon as the dimension N of the Hilbert space is at least three. On the other hand, a complete physical observable A is associated with a N-dimensional orthogonal basis of eigenvectors. In an idealized case, measuring A again and again will give repeatedly the same result, with the same eigenvalue. Let us call this repeatable result a modality \, and the corresponding eigenstate (...) \. A question is then: does \ give a complete description of \? The answer is obviously no, since \ does not specify the full observable A that allowed us to obtain \; hence the physical description given by \ is incomplete, as claimed by Einstein, Podolsky and Rosen in their famous article in 1935. Here we want to spell out this provocative statement, and in particular to answer the questions: if \ is an incomplete description of \, what does it describe? is it possible to obtain a complete description, maybe algebraic? Our conclusion is that the incompleteness of standard QM is due to its attempt to describe systems without contexts, whereas both are always required, even if they can be separated outside the measurement periods. (shrink)

We provide a constructive, direct, and simple proof of the completeness of the cut-free part of the hypersequential calculus for G¨odel logic (thereby proving both completeness of the calculus for its standard semantics, and the admissibility of the cut rule in the full calculus). We then extend the results and proofs to derivations from assumptions, showing that such derivations can be confined to those in which cuts are made only on formulas which occur in the assumptions.

The addition of "actually" operators to modal languages allows us to capture important inferential behaviours which cannot be adequately captured in logics formulated in simpler languages. Previous work on modal logics containing "actually" operators has concentrated entirely upon extensions of KT5 and has employed a particular modeltheoretic treatment of them. This paper proves completeness and decidability results for a range of normal and nonnormal but quasi-normal propositional modal logics containing "actually" operators, the weakest of which are conservative extensions of (...) K, using a novel generalisation of the standard semantics. (shrink)

Consider the following. The first is a one-premise argument; the second has two premises. The question sign marks the conclusions as such. -/- Matthew, Mark, Luke, and John wrote Greek. ? Every evangelist wrote Greek. -/- Matthew, Mark, Luke, and John wrote Greek. Every evangelist is Matthew, Mark, Luke, or John. ? Every evangelist wrote Greek. -/- The above pair of premise-conclusion arguments is of a sort familiar to logicians and philosophers of science. In each case the first premise is (...) logically equivalent to the set of four atomic propositions: “Matthew wrote Greek”, “Mark wrote Greek”, “Luke wrote Greek”, and “John wrote Greek”. The universe of discourse is the set of evangelists. We presuppose standard first-order logic. -/- As many logic texts teach, the first of these two premise-conclusion arguments—sometimes called a complete enumerative induction— is invalid in the sense that its conclusion does not follow from its premises. To get a counterargument, replace ‘Matthew’, ‘Mark’, ‘Luke’, and ‘John’ by ‘two’,’four’, ‘six’ and ‘eight’; replace ‘wrote Greek’ by ‘are even’; and replace ‘evangelist’ by ‘number’. This replacement converts the first argument into one having true premises and false conclusion. -/- But the same replacement performed on the second argument does no such thing: it converts the second premise into the falsehood “Every number is two, four, six, or eight”. As many logic texts teach, there is no replacement that converts the second argument into one with all true premises and false conclusion. The second is valid; its conclusion is deducible from its two premises using an instructive natural deduction. -/- This paper “does the math” behind the above examples. The theorem could be stated informally: the above examples are typical. (shrink)

Higher-order theories of properties, relations, and propositions are known to be essentially incomplete relative to their standard notions of validity. It turns out that the first-order theory of PRPs that results when first-order logic is supplemented with a generalized intensional abstraction operation is complete. The construction involves the development of an intensional algebraic semantic method that does not appeal to possible worlds, but rather takes PRPs as primitive entities. This allows for a satisfactory treatment of both the modalities and (...) the propositional attitudes, and it suggests a general strategy for developing a comprehensive treatment of intensional logic. (shrink)

If completeness is going to be upheld as a standard of ethical journalism, then journalists cannot continue to systematically exclude certain groups of people from coverage. Using ethnographic methodology, this study looks at the experiences of a group of Hispanic television journalists in 1 market. These journalists identify problem areas, including the idea that news values are still infused with White maleness, which may impact not only news coverage but also the career progress of Hispanic journalists.

There is a good deal of biomedical research that does not produce scientifically useful data because it fails to recruit a sufficient number of subjects. This fact is typically not disclosed to prospective subjects. In general, the guidance about consent concerns the information required to make intelligent self-interested decisions and ignores some of the information required for intelligent altruistic decisions. Bioethics has worried about the ‘therapeutic misconception’, but has ignored the ‘completion misconception’. This article argues that, other things being equal, (...) prospective subjects should be informed about the possibility of non-completion as part of the standard consent process if it is or should be anticipatable that there is a non-trivial possibility of non-completion and that information is likely to be relevant to a prospective subject's decision to consent. The article then considers several objections to the argument, including the objection that disclosing non-completion information would make recruitment even more difficult. (shrink)

Vardoulakis’s ambitious work stems from his perception of the inability of Heidegger’s thought in particular, and of continental philosophy in general, to account for human action in the absence of an understanding of human ends. His specific contention is that this deficiency stems from a mistranslation of Aristotle by Heidegger, whereby Heidegger conflates the ends of phronesis with those of techne. Unfortunately, this contention is itself based on a mistranslation of the Greek. The true argument between Aristotle and Heidegger does (...) not depend upon the difference between the ends of techne and phronesis, but upon the question as to whether our standards for judging human action and thought are given historically or by nature. Heidegger contends that the source of the significance of all things is a mysterious, historical dispensation inaccessible to reason. We are left only with ‘hope’ of a new dispensation, an attitude Vardoulakis rightly finds inadequate. Aristotle’s contention that art or artifice (techne, nomos, poiesis, or ethos) completes or imitates nature can comprehend both constructed or artificial aspects of our ordinary experience and institutions while doing justice to our perception that there are intelligible standards by which we can judge ourselves and others. I suggest the merit of Vardoulakis’s intention is better realized by a return to Aristotle’s understanding of the ends of human action. (shrink)

A μ-algebra is a model of a first-order theory that is an extension of the theory of bounded lattices, that comes with pairs of terms where μx.f is axiomatized as the least prefixed point of f, whose axioms are equations or equational implications.Standard μ-algebras are complete meaning that their lattice reduct is a complete lattice. We prove that any nontrivial quasivariety of μ-algebras contains a μ-algebra that has no embedding into a complete μ-algebra.We then focus on modal μ-algebras, i.e. (...) algebraic models of the propositional modal μ-calculus. We prove that free modal μ-algebras satisfy a condition–reminiscent of Whitman’s condition for free lattices–which allows us to prove that modal operators are adjoints on free modal μ-algebras, least prefixed points of Σ1-operations satisfy the constructive relation μx.f=logical and operatorn≥0fn. These properties imply the following statement: the MacNeille–Dedekind completion of a free modal μ-algebra is a complete modal μ-algebra and moreover the canonical embedding preserves all the operations in the class image of the fixed point alternation hierarchy. (shrink)

Several authors have hypothesized that completely positive maps should provide the means for generalizing quantum dynamics. In a critical analysis of that proposal, we show that such maps are incompatible with the standard phenomenological theory of spin relaxation and that the theoretical argument which has been offered as justification for the hypothesis is fallacious.

Many works are attributed to artists after their death, even when someone else has contributed substantively to the content of the work or when the work left by the artist is deemed incomplete by any standard of completion. Call these works posthumous works.1 Consider, for instance, Garden of Eden, Mysterious Stranger, Silmarillion, Symphony No. 10, Symphony No. 7, Sagrada Familia, the film A.I., Woyzeck, to name just a few. These are examples where..

The standard axiomatization of quantum mechanics (QM) is not fully explicit about the role of the time-parameter. Especially, the time reference within the probability algorithm (the Born Rule, BR) is unclear. From a probability principle P1 and a second principle P2 affording a most natural way to make BR precise, a logical conflict with the standard expression for the completeness of QM can be derived. Rejecting P1 is implausible. Rejecting P2 leads to unphysical results and to a (...) conflict with a generalization of P2, a principle P3. All three principles are shown to be without alternative. It is thus shown that the standard expression of QM completeness must be revised. An absolutely explicit form of the axioms is provided, including a precise form of the projection postulate. An appropriate expression for QM completeness, reflecting the restrictions of the Gleason and Kochen-Specker theorems is proposed. (shrink)

The set of complete groups is a complete co-analytic subset of the standard Borel space of countably infinite groups.

In this paper, I challenge the standard reading of complete virtue (ἀρετή τελεία) in those disputed passages of Nicomachean Ethics and Eudemian Ethics. I argue that, for Aristotle, complete virtue is neither (i) wisdom nor (ii) a whole set of all virtues. Rather, it is a term used by Aristotle to denote any virtue that is in its complete or perfect form. In light of this reading, I offer a pluralist interpretation of Aristotelian happiness. I argue that for Aristotle, (...) the life-long exercise of a predominant virtue—as long as it is exercised in its complete or perfect form—will suffice for human happiness. The so-called inclusivist and intellectualist notions of Aristotelian happiness, thus understood, are merely two forms (viz. the composite and the non-composite form) of the pluralist notion of Aristotelian happiness. And if I am right, my pluralist interpretation provides an alternative, if not better, solution to the long-standing problem of “dual happiness” in Aristotle. (shrink)

We prove strong completeness results for some modal logics with the universal modality, with respect to their topological semantics over 0-dimensional dense-in-themselves metric spaces. We also use failure of compactness to show that, for some languages and spaces, no standard modal deductive system is strongly complete.

We propose a new approach to positive modal logics, hereby called anodic modal logics. Our treatment is completely positive since the language has neither negation nor any falsum or minimal particle. The elimination of the minimal particle of the language requires introducing the new concept of factual sets and factual deductions which permit us to talk about deductions in the actual world. We start from a positive fragment of the standard system K, denoted by K⊃, ∧, ◊, which is (...) a bimodal system with □ and ◊ as primitive. This system is then extended to a class of fragments of the Lemmon and Scott systems (cf. (Lemmon et al., 1977)), denoted by K⊃, ∧, ◊ + Gk;l;m;n + Gm;n;k;l. It is shown that such classes of systems are characterized with respect to the usual Kripke-style semantics. The proof is by way of a Henkin-style construction, with “possible worlds” being taken to be prime theories as introduced in the modal context by J. M. Dunn in (Dunn, 1995). We also obtain a surprising limiting result showing that the incompleteness phenomenon in modal logic is independent of negation. (shrink)

The Oxford Translation of Aristotle was originally published in 12 volumes between 1912 and 1954. It is universally recognized as the standard English version of Aristotle. This revised edition contains the substance of the original Translation, slightly emended in light of recent scholarship; three of the original versions have been replaced by new translations; and a new and enlarged selection of Fragments has been added. The aim of the translation remains the same: to make the surviving works of Aristotle (...) readily accessible to English speaking readers. (shrink)

Standard theories of expected utility require that preferences are complete, and/or Archimedean. We present in this paper a theory of decision under uncertainty for both incomplete and non-Archimedean preferences. Without continuity assumptions, incomplete preferences on a lottery space reduce to an order-extension problem. It is well known that incomplete preferences can be extended to complete preferences in the full generality, but this result does not necessarily hold for incomplete preferences which satisfy the independence axiom, since it may obviously happen (...) that the extension does not satisfy the independence axiom. We show, for incomplete preferences on a mixture space, that an extension which satisfies the independence axiom exists. We find necessary and sufficient conditions for a preorder on a finite lottery space to be representable by a family of lexicographic von Neumann–Morgenstern Expected Utility functions. (shrink)

The Oxford Translation of Aristotle was originally published in 12 volumes between 1912 and 1954. It is universally recognized as the standard English version of Aristotle. This revised edition contains the substance of the original Translation, slightly emended in light of recent scholarship; three of the original versions have been replaced by new translations; and a new and enlarged selection of Fragments has been added. The aim of the translation remains the same: to make the surviving works of Aristotle (...) readily accessible to English speaking readers. (shrink)

In what sense, and to what extent, do rules of inference determine the meaning of logical constants? Motivated by the principle of charity, a natural constraint on the interpretation of logical constants is to make the rules of inference come out sound. But, as Carnap observed, although this constraint does rule out some non-standard interpretations, it does not rule them all out. This is known as Carnap’s problem. I suggest that a charitable interpretation of the logical constants should, as (...) far as possible, make the rules of inference both sound and complete, and I show how this idea can be brought to bear on a successful solution to Carnap’s problem in the case of classical propositional logic, as well as classical first-order logic. In fact, the solution generalizes to any logic whose rules of inference are sound and complete with respect to a bivalent semantics that is classical with respect to negation. (shrink)

Ken Pledger devised a one-sorted approach to the incidence relation of plane geometries, using structures that also support models of propositional modal logic. He introduced a modal system 12g that is valid in one-sorted projective planes, proved that it has finitely many non-equivalent modalities, and identified all possible modality patterns of its extensions. One of these extensions 8f is valid in elliptic planes. These results were presented in his 1980 doctoral dissertation, which is reprinted in this issue of the Australasian (...) Journal of Logic. Here we show that 12g and 8f are strongly complete for validity in their intended one-sorted geometrical interpretations, and have the finite model property. The proofs apply standard technology of modal logic together with a step-by-step procedure introduced by Yde Venema for constructing two-sorted projective planes. (shrink)

Earlier in this century, many philosophers of science (for example, Rudolf Carnap) drew a fairly sharp distinction between theory and observation, between theoretical terms like 'mass' and 'electron', and observation terms like 'measures three meters in length' and 'is _2° Celsius'. By simply looking at our instruments we can ascertain what numbers our measurements yield. Creatures like mass are different: we determine mass by calculation; we never directly observe a mass. Nor an electron: this term is introduced in order to (...) explain what we observe. This (once standard) distinction between theory and observation was eventually found to be wanting. First, if the distinction holds, it is difficult to see what can characterize the relationship between theory :md observation. How can theoretical terms explain that which is itself in no way theorized? The second point leads out of the first: are not the instruments that provide us with observational material themselves creatures of theory? Is it really possible to have an observation language that is entirely barren of theory? The theory-Iadenness of observation languages is now an accept ed feature of the logic of science. Many regard such dependence of observation on theory as a virtue. If our instruments of observation do not derive their meaning from theories, whence comes that meaning? Surely - in science - we have nothing else but theories to tell us what to try to observe. (shrink)

I propose a version of quantum mechanics featuring a discrete and finite number of states that is plausibly a model of the real world. The model is based on standard unitary quantum theory of a closed system with a finite-dimensional Hilbert space. Given certain simple conditions on the spectrum of the Hamiltonian, Schrödinger evolution is periodic, and it is straightforward to replace continuous time with a discrete version, with the result that the system only visits a discrete and finite (...) set of state vectors. The biggest challenges to the viability of such a model come from cosmological considerations. The theory may have implications for questions of mathematical realism and finitism. (shrink)

We introduce a basic intuitionistic conditional logic $\textsf{IntCK}$ that we show to be complete both relative to a special type of Kripke models and relative to a standard translation into first-order intuitionistic logic. We show that $\textsf{IntCK}$ stands in a very natural relation to other similar logics, like the basic classical conditional logic $\textsf{CK}$ and the basic intuitionistic modal logic $\textsf{IK}$. As for the basic intuitionistic conditional logic $\textsf{ICK}$ proposed in Weiss (_Journal of Philosophical Logic_, _48_, 447–469, 2019 ), (...) $\textsf{IntCK}$ extends its language with a diamond-like conditional modality $\Diamond \hspace{-4.0pt}\rightarrow$, but its ( $\Diamond \hspace{-4.0pt}\rightarrow$ )-free fragment is also a proper extension of $\textsf{ICK}$. We briefly discuss the resulting gap between the two candidate systems of basic intuitionistic conditional logic and the possible pros and cons of both candidates. (shrink)

An algebraic setting for the validity of Pavelka style completeness for some natural expansions of Łukasiewicz logic by new connectives and rational constants is given. This algebraic approach is based on the fact that the standard MV-algebra on the real segment [0, 1] is an injective MV-algebra. In particular the logics associated with MV-algebras with product and with divisible MV-algebras are considered.

In the present paper, we start studying epistemic updates using the standard toolkit of duality theory. We focus on public announcements, which are the simplest epistemic actions, and hence on Public Announcement Logic without the common knowledge operator. As is well known, the epistemic action of publicly announcing a given proposition is semantically represented as a transformation of the model encoding the current epistemic setup of the given agents; the given current model being replaced with its submodel relativized to (...) the announced proposition. We dually characterize the associated submodel-injection map as a certain pseudo-quotient map between the complex algebras respectively associated with the given model and with its relativized submodel. As is well known, these complex algebras are complete atomic BAOs . The dual characterization we provide naturally generalizes to much wider classes of algebras, which include, but are not limited to, arbitrary BAOs and arbitrary modal expansions of Heyting algebras . Thanks to this construction, the benefits and the wider scope of applications given by a point-free, intuitionistic theory of epistemic updates are made available. As an application of this dual characterization, we axiomatize the intuitionistic analogue of PAL, which we refer to as IPAL, prove soundness and completeness of IPAL w.r.t. both algebraic and relational models, and show that the well known Muddy Children Puzzle can be formalized in IPAL. (shrink)

Causal discovery becomes especially challenging when the possibility of latent confounding and/or selection bias is not assumed away. For this task, ancestral graph models are particularly useful in that they can represent the presence of latent confounding and selection effect, without explicitly invoking unobserved variables. Based on the machinery of ancestral graphs, there is a provably sound causal discovery algorithm, known as the FCI algorithm, that allows the possibility of latent confounders and selection bias. However, the orientation rules used in (...) the algorithm are not complete. In this paper, we provide additional orientation rules, augmented by which the FCI algorithm is shown to be complete, in the sense that it can, under standard assumptions, discover all aspects of the causal structure that are uniquely determined by facts of probabilistic dependence and independence. The result is useful for developing any causal discovery and reasoning system based on ancestral graph models. (shrink)

This article is an extended promenade strolling along the winding roads of identity, equality, nameability and completeness, looking for places where they converge. We have distinguished between identity and equality; the first is a binary relation between objects while the second is a symbolic relation between terms. Owing to the central role the notion of identity plays in logic, you can be interested either in how to define it using other logical concepts or in the opposite scheme. In the (...) first case, one investigates what kind of logic is required. In the second case, one is interested in the definition of the other logical concepts in terms of the identity relation, using also abstraction. The present paper investigates whether identity can be introduced by definition arriving to the conclusion that only in full higher-order logic a reliable definition of identity is possible. However, the definition needs the standard semantics and we know that with this semantics completeness is lost. We have also studied the relationship of equality with comprehension and extensionality and pointed out the relevant role played by these two axioms in Henkin’s completeness method. We finish our paper with a section devoted to general semantics, where the role played by the nameable hierarchy of types is the key in Henkin’s completeness method. (shrink)

In [10] it is claimed that the set of predicate tautologies of all complete BL-chains and the set of all standard tautologies coincide. As noticed in [11], this claim is wrong. In this paper we show that a complete BL-chain B satisfies all standard BL-tautologies iff for any transfinite sequence of elements of B, the condition ∧i ∈ I = 2 holds in B.