We study some operations that may be defined using the minimum operator in the context of a Heyting algebra. Our motivation comes from the fact that 1) already known compatible operations, such as the successor by Kuznetsov, the minimum dense by Smetanich and the operation G by Gabbay may be defined in this way, though almost never explicitly noted in the literature; 2) defining operations in this way is equivalent, from a logical point of view, to two clauses, one corresponding (...) to an introduction rule and the other to an elimination rule, thus providing a manageable way to deal with these operations. Our main result is negative: all operations that arise turn out to be Heyting terms or the mentioned already known operations or operations interdefinable with them. However, it should be noted that some of the operations that arise may exist even if the known operations do not. We also study the extension of Priestley duality to Heyting algebras enriched with the new operations. (shrink)

An l-hemi-implicative semilattice is an algebra $$\mathbf {A} = $$ A= such that $$$$ is a semilattice with a greatest element 1 and satisfies: for every $$a,b,c\in A$$ a,b,c∈A, $$a\le b\rightarrow c$$ a≤b→c implies $$a\wedge b \le c$$ a∧b≤c and $$a\rightarrow a = 1$$ a→a=1. An l-hemi-implicative semilattice is commutative if if it satisfies that $$a\rightarrow b = b\rightarrow a$$ a→b=b→a for every $$a,b\in A$$ a,b∈A. It is shown that the class of l-hemi-implicative semilattices is a variety. These algebras provide (...) a general framework for the study of different algebras of interest in algebraic logic. In any l-hemi-implicative semilattice it is possible to define an derived operation by $$a \sim b := \wedge $$ a∼b:=∧. Endowing $$$$ with the binary operation $$\sim $$ ∼ the algebra $$$$ results an l-hemi-implicative semilattice, which also satisfies the identity $$a \sim b = b \sim a$$ a∼b=b∼a. In this article, we characterize the commutative l-hemi-implicative semilattices. We also provide many new examples of l-hemi-implicative semilattice on any semillatice with greatest element. Finally, we characterize congruences on the classes of l-hemi-implicative semilattices introduced earlier and we characterize the principal congruences of l-hemi-implicative semilattices. (shrink)

An equivalence between the category of MV-algebras and the category $${{\rm MV^{\bullet}}}$$ MV ∙ is given in Castiglioni et al. :67–92, 2014). An integral residuated lattice with bottom is an MV-algebra if and only if it satisfies the equations $${a = \neg \neg a, \vee = 1}$$ a = ¬ ¬ a, ∨ = 1 and $${a \odot = a \wedge b}$$ a ⊙ = a ∧ b. An object of $${{\rm MV^{\bullet}}}$$ MV ∙ is a residuated lattice which in (...) particular satisfies some equations which correspond to the previous equations. In this paper we extend the equivalence to the category whose objects are pairs, where A is an MV-algebra and I is an ideal of A. (shrink)

In this paper we introduce and study a variety of algebras that properly includes integral distributive commutative residuated lattices and weak Heyting algebras. Our main goal is to give a characterization of the principal congruences in this variety. We apply this description in order to study compatible functions.

Let \({\mathcal {K}}\) be a quasivariety. We say that \({\mathcal {K}}\) is a term quasivariety if there exist an operation of arity zero _e_ and a family of binary terms \(\{t_i\}_{i\in I}\) such that for every \(A \in {\mathcal {K}}\), \(\theta \) a \({\mathcal {K}}\) -congruence of _A_ and \(a,b\in A\) the following condition is satisfied: \((a,b)\in \theta \) if and only if \((t_{i}(a,b),e) \in \theta \) for every \(i\in I\). In this paper we study term quasivarieties. For every \(A\in (...) {\mathcal {K}}\) and \(a,b\in A\) we present a description for the smallest \({\mathcal {K}}\) -congruence containing the pair (_a_, _b_). We apply this result in order to characterize \({\mathcal {K}}\) -compatible functions on _A_ (i.e., functions which preserve all the \({\mathcal {K}}\) -congruences of _A_) and we give two applications of this property: (1) we give necessary conditions on \({\mathcal {K}}\) for which for every \(A \in {\mathcal {K}}\) the \({\mathcal {K}}\) -compatible functions on _A_ coincides with a polynomial over finite subsets of _A_; (2) we give a method to build up \({\mathcal {K}}\) -compatible functions. (shrink)

This paper deals about dualities for bounded prelinear Hilbert algebras. In particular, we give an Esakia-style duality between the algebraic category of bounded prelinear Hilbert algebras and a category of H-spaces whose morphisms are certain continuous p-morphisms.

In this paper we introduce and study a variety of algebras that properly includes integral distributive commutative residuated lattices and weak Heyting algebras. Our main goal is to give a characterization of the principal congruences in this variety. We apply this description in order to study compatible functions.

An l-hemi-implicative semilattice is an algebra \\) such that \\) is a semilattice with a greatest element 1 and satisfies: for every \, \ implies \ and \. An l-hemi-implicative semilattice is commutative if if it satisfies that \ for every \. It is shown that the class of l-hemi-implicative semilattices is a variety. These algebras provide a general framework for the study of different algebras of interest in algebraic logic. In any l-hemi-implicative semilattice it is possible to define an (...) derived operation by \ \wedge \). Endowing \\) with the binary operation \ the algebra \\) results an l-hemi-implicative semilattice, which also satisfies the identity \. In this article, we characterize the commutative l-hemi-implicative semilattices. We also provide many new examples of l-hemi-implicative semilattice on any semillatice with greatest element. Finally, we characterize congruences on the classes of l-hemi-implicative semilattices introduced earlier and we characterize the principal congruences of l-hemi-implicative semilattices. (shrink)

Extending the relation between semi-Heyting algebras and semi-Nelson algebras to dually hemimorphic semi-Heyting algebras, we introduce and study the variety of dually hemimorphic semi-Nelson algebras and some of its subvarieties. In particular, we prove that the category of dually hemimorphic semi-Heyting algebras is equivalent to the category of dually hemimorphic centered semi-Nelson algebras. We also study the lattice of congruences of a dually hemimorphic semi-Nelson algebra through some of its deductive systems.

An equivalence between the category of MV-algebras and the category \ is given in Castiglioni et al. :67–92, 2014). An integral residuated lattice with bottom is an MV-algebra if and only if it satisfies the equations \ \vee = 1}\) and \ = a \wedge b}\). An object of \ is a residuated lattice which in particular satisfies some equations which correspond to the previous equations. In this paper we extend the equivalence to the category whose objects are pairs, where (...) A is an MV-algebra and I is an ideal of A. (shrink)

In this paper we shall introduce the variety FWHA of frontal weak Heyting algebras as a generalization of the frontal Heyting algebras introduced by Leo Esakia in [ 10 ]. A frontal operator in a weak Heyting algebra A is an expansive operator τ preserving finite meets which also satisfies the equation $${\tau(a) \leq b \vee (b \rightarrow a)}$$, for all $${a, b \in A}$$. These operators were studied from an algebraic, logical and topological point of view by Leo Esakia (...) in [ 10 ]. We will study frontal operators in weak Heyting algebras and we will consider two examples of them. We will give a Priestley duality for the category of frontal weak Heyting algebras in terms of relational spaces $${\langle X, \leq, T, R \rangle}$$ where $${\langle X, \leq, T \rangle}$$ is a WH -space [ 6 ], and R is an additional binary relation used to interpret the modal operator. We will also study the WH -algebras with successor and the WH -algebras with gamma. For these varieties we will give two topological dualities. The first one is based on the representation given for the frontal weak Heyting algebras. The second one is based on certain particular classes of WH -spaces. (shrink)

In this paper we shall prove that certain subvarieties of the variety of Salgebras (Heyting algebras with successor) has amalgamation. This result together with an appropriate version of Theorem 1 of [L. L. Maksimova, Craig’s theorem in superintuitionistic logics and amalgamable varieties of pseudo-boolean algebras, Algebra i Logika, 16(6):643-681, 1977] allows us to show interpolation in the calculus IPC S (n), associated with these varieties.We use that every algebra in any of the varieties of S-algebras studied in this work has (...) a canonical extension, to show completeness of the calculus IPC S (n) with respect to appropriate Kripke models. (shrink)

A subresiduated lattice is a pair, where A is a bounded distributive lattice, D is a bounded sublattice of A and for every there exists the maximum of the set, which is denoted by. This pair can be regarded as an algebra of type (2, 2, 2, 0, 0), where. The class of subresiduated lattices is a variety which properly contains the variety of Heyting algebras. In this paper we study the subvariety of subresiduated lattices, denoted by, whose members satisfy (...) the equation. Inspired by the fact that in any subresiduated lattice whose order is total the previous equation and the condition for every are satisfied, we also study the subvariety of generated by the class whose members satisfy that for every. (shrink)

We study some operations that may be defined using the minimum operator in the context of a Heyting algebra. Our motivation comes from the fact that 1) already known compatible operations, such as the successor by Kuznetsov, the minimum dense by Smetanich and the operation G by Gabbay may be defined in this way, though almost never explicitly noted in the literature; 2) defining operations in this way is equivalent, from a logical point of view, to two clauses, one corresponding (...) to an introduction rule and the other to an elimination rule, thus providing a manageable way to deal with these operations. Our main result is negative: all operations that arise turn out to be Heyting terms or the mentioned already known operations or operations interdefinable with them. However, it should be noted that some of the operations that arise may exist even if the known operations do not. We also study the extension of Priestley duality to Heyting algebras enriched with the new operations. (shrink)

A hemi-implicative lattice is an algebra \((A,\wedge,\vee,\rightarrow,1)\) of type (2, 2, 2, 0) such that \((A,\wedge,\vee,1)\) is a lattice with top and for every \(a,b\in A\), \(a\rightarrow a = 1\) and \(a\wedge (a\rightarrow b) \le b\). A new variety of hemi-implicative lattices, here named sub-Hilbert lattices, containing both the variety generated by the \(\{\wedge,\vee,\rightarrow,1\}\) -reducts of subresiduated lattices and that of Hilbert lattices as proper subvarieties is defined. It is shown that any sub-Hilbert lattice is determined (up to isomorphism) by (...) a triple (_L_, _D_, _S_) which satisfies the following conditions: _L_ is a bounded distributive lattice, _D_ is a sublattice of _L_ containing 0, 1 such that for each \(a, b \in L\) there is an element \(c \in D\) with the property that for all \(d \in D\), \(a \wedge d \le b\) if and only if \(d \le c\) (we write \(a \rightarrow _D b\) for the element _c_), and _S_ is a non void subset of _L_ such that _S_ is closed under \(\rightarrow _D\) and _S_, with its inherited order, is itself a lattice. Finally, the congruences of sub-Hilbert lattices are studied. (shrink)

In this paper we study the variety \(\textsf{WL}\) of bounded distributive lattices endowed with an implication, called weak Lewis distributive lattices. This variety corresponds to the algebraic semantics of the \(\{\vee,\wedge,\Rightarrow,\bot,\top \}\) -fragment of the arithmetical base preservativity logic \(\mathsf {iP^{-}}\). The variety \(\textsf{WL}\) properly contains the variety of bounded distributive lattices with strict implication, also known as weak Heyting algebras. We introduce the notion of WL-frame and we prove a representation theorem for WL-lattices by means of WL-frames. We extended (...) this representation to a topological duality by means of Priestley spaces endowed with a special neighbourhood relation between points and closed upsets of the space. These results are applied in order to give a representation and a topological duality for the variety of weak Heyting–Lewis algebras, i.e., for the algebraic semantics of the arithmetical base preservativity logic \(\textsf{iP}^{-}\). (shrink)

Mi intención en esta ponencia es hacerles una presentación de la fenomenología en España, para lo cual repetiré ideas que he expresado en la introducción al libro de Ortega Schriften zur Phänomenologie 15 y, en segundo lugar, resumiré una parte del contenido de la conferencia que pronuncié en el penúltimo Congreso de la Sociedad Española de Fenomenología. 16.

Mi ponencia trata de contribuir a una fenomenología de la percepción, desde la discusión de las posturas sobre la percepción que aparecen en la reciente obra de Lester Embree sobre el método fenomenológico. Desde el convencimiento y asentimiento a la llamada de Lester Embree, de que debemos volver a las cosas mismas, por tanto, dejamos de la erudición para alumbrar fenomenología de las cosas, no podemos tampoco desentendemos de lo que dicen nuestros maestros, y pretendo, con ellos, ir a las (...) cosas, para ver en qué medida la percepción como acceso al mundo es un “acto” en el que intervienen la experiencia directa sensible animal y la aportación lingüística que clasifica el mundo, sin por ello convertir la percepción en lenguaje. En el primer punto plantearé la importancia que el tema tiene en la fenomenología sobre todo por el planteamiento husserliana en las Ideas I. En el segundo veremos la postura de Lester Embree, para, en el tercero, exponer lo que yo creo que está implícito en la propuesta de Husserl, que explicita la percepción como el acceso ponente a la realidad, por tanto radicalmente vinculada a la creencia, de manera que, fenomenológicamente, percepción, creencia y realidad están vinculadas, siendo está vinculación el marco en el que sitúa el comienzo de la legitimidad racional. (shrink)

In the first part of my paper, we will journey through the general structure of the first volume of Ideas, from which we will be able to deduce the position of Volume II. After carrying out a general analysis of the noesis/noema correlation structure in Section III and having provided, in Section IV, the basics of a phenomenology of reason, the second volume of Ideas should study the general fields in which the objects of transcendental experience appear: the world, the (...) animal being, and the spiritual or cultural being. The third, unwritten volume should have been devoted to the study of the superior products of culture, and science. Thus, the second part of this paper will show the place of Ideas’ second volume. The third part, the decisive one, will inquire into the position of the world and the place of the body and culture. Specifically, it will ask whether the experience of the body is understood to be an objective genitive or whether it is also understood, necessarily, as a subjective genitive. The same question will be asked about culture. An understanding of one as objective or subjective genitive radically alters the meaning of the pure ego. (shrink)

The author deals with philosophical ethos in its practical function. After the First World War Husserl not only considers the structure but also the function of phenomenology. A meditation on this function, with regard to the history of philosophy, is his primal task in the Freiburg years. Thus the possibility of developing a rigorous phenomenology of practical reason becomes the basis of phenomenology. The importance of Husserl’s characterization of life in terms of striving is stressed as a key motive in (...) the turn from static to genetic phenomenology. It is argued that instinctive life is inserted in a cultural development that shapes a theoretical side providing content to our primal tendencies as well as the identity of individuals. A decisive point in genetic phenomenology is the passage from instinctive animality to human life. This development rests on a pretheoretic affectivity that colors life as a sort of subconsciousness underlying all our activities. It is the originary stratum through which we approach the world. The article goes on to high-light the importance of Husserl’s concept of culture and specifically of his practical concept of culture which is made up of life-regulations and without which an ideal and a technical culture are devoid of a ground. Finally, the author considers life-regulations as a key problem to be dealt with by phenomenology first in the emotional and then in the practical level. (shrink)

En philosophie, le personnage conceptuel trace une nouvelle image de la pensée. Au cinéma, avec la modernité, le personnage découvre une nouvelle image. Après la crise de I’image-action, les signes ne se reconnaissent pas plus qu ’ils ne se déduisent : ils se voient. Celui qui voit, c’est le personnage. Dans cette vision, il devient I’inventeur de nouvelles façons de percevoir. Il est á la fois producteur et créateur. Le propre du personnage conceptuel réside aussi en la création non pas (...) de percepts, mais de concepts. À partir de ces deux constatations, il nous semble intéressant de commenter le troisième chapitre de Qu’est-ce que la philosophie? qui porte sur le personnage conceptuel et de faire une analyse du voyant, personnage de cinéma, qui apparaît dans le premier chapitre de L’image-temps. Grâce à cette étude croisée nous espérons trouver des recoupements et des liens entre personnage, pensée et perception. (shrink)

Meditaciones del Quijote, el primer libro de Ortega y Gasset, es un libro de “encrucijada”, palabra que significa cruce de caminos. El presente texto analiza el concepto de cultura, que por un lado viene de la fenomenología, pero por otro mantiene la matriz neokantiana. Por un lado es el modo de ver y apreciar el mundo, mas por otro se refiere a los modos superiores de la cultura, tal como se entendía en el mundo académico alemán.