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Hugo Luiz Mariano

Publications and source records attributed to Hugo Luiz Mariano.

At least 37 records · Page 2Linked to original sources
arXiv2021

Congruence Filter Pairs, Adjoints and Leibniz Hierarchy

We review the notion of (finitary) filter pair as a tool for creating and analyzing logics. A filter pair can be seen as a presentation of a logic, given by presenting its lattice of theories as the image of a lattice homomorphism, with certain properties ensuring that the resulting logic is finitary and substitution invariant. Every finitary, substitution invariant logic arises from a filter pair. Particular classes of logics can be characterized as arising from special classes of filter pairs. We consider so-called congruence filter pairs, i.e. filter pairs for which the domain of the lattice homomorphism is a lattice of congruences for some quasivariety. We show that the class of logics admitting a presentation by such a filter pair is exactly the class of logics having an algebraic semantics. We study the properties of a certain Galois connection coming with such filter pairs. We give criteria for a congruence filter pair to present a logic in some classes of the Leibniz hierarchy by means of this Galois connection, and its interplay with the Leibniz operator. As an application, we show a bridge theorem, stating that the amalgamation property implies the Craig interpolation property, for a certain class of logics including non-protoalgebraic logics.

math.LO↗
arXiv2021

On sheaf cohomology and natural expansions

In this survey paper, we present Čech and sheaf cohomologies -- themes that were presented by Koszul in University of São Paulo during his visit in the late 1950s -- we present expansions for categories of generalized sheaves (i.e, Grothendieck toposes), with examples of applications in other cohomology theories and other areas of mathematics, besides providing motivations and historical notes. We conclude explaining the difficulties in establishing a cohomology theory for elementary toposes, presenting alternative approaches by considering constructions over quantales, that provide structures similar to sheaves, and indicating researches related to logic: constructive (intuitionistic and linear) logic for toposes, sheaves over quantales, and homological algebra.

math.CT↗
arXiv2021

von Neumann regular Hyperrings and applications to Real Reduced Multirings

A multiring ([Mar3]) is a kind of ring where is allowed the sum of two elements to be anon-empty subset of the structure instead of just one element -and an hyperring is a multiring with a strong distributive property. Thus a reduced hyperring where the prime spec is a Boolean topological space is called von Neumann regular hyperring (vNH). It is possible to associate to every such object a structural presheaf in the same way it is made with rings but there are some vNH such that this presheaf is not a sheaf. In this sense, we give a first-order characterization of vNH with a structural sheaf (geometric vNH or just GvNH) and how to transform a vNH in aGvNH -in fact, this transformation shows that the category GvNH is a reflexive subcategory of vNH. We also build a von Neumann regular hull for multirings and use this to give applications for algebraic theory of quadratic forms. More precisely, we work with Real Reduced Multiring (RRM, [Mar3]) -also known as Real Semigroup (RS, [DP1])-, a special kind of multirings that is useful to explore the real structure of rings, and show that a von Neumann hull of a RRM is again a RRM. This gives a generalization of sheafs arguments present in [DM4].

math.AC↗
arXiv2020

Connecting abstract logics and adjunctions in the theory of ($π$-)institutions: some theoretical remarks and applications

In the present work, a natural sequel to \cite{MaPi1}, we further discuss the existence of adjunctions between categories of institutions and of $π$-institutions. This is done at both a foundational and an applied level. Firstly, we reformulate and conceptually clarify such adjunctions in terms of the $2$-categorical data involved in the construction of categories of institution-like structures. More precisely, we remark that the process used for passing from rooms to institutions (\cite{Diac2}) can be extended, due to its $2$-functoriality, to more general room-like and institution-like structures in such a way that the aforementioned adjunctions are all seen to arise from simpler adjunctions at the room-like level. Secondly, and mostly independently, we provide some applications of such adjunctions to abstract logics, mainly to the setting of propositional logics and filter pairs (\cite{AMP1}); we also generalize the process of skolemization, a classical device from predicate logic, to the institutional setting.

math.LO↗
arXiv2020

Topics on Smooth Commutative Algebra

We present, in the same vein as in [20] and [21], some results of the so-called "Smooth (or $\mathcal{C}^\infty$) Commutative Algebra", a version of Commutative Algebra of $\mathcal{C}^{\infty}-$rings instead of ordinary commutative unital rings, looking for similar results to those one finds in the latter, and expanding some others presented in [20]. We give an explicit description of an adjunction between the categories $\mathcal{C}^\infty{\rm Rng}$ and ${\rm CRing}$, in order to study this "bridge". We present and prove many properties of the analog of the radical of an ideal of a ring (namely, the $\mathcal{C}^\infty$-radical of an ideal), saturation (which we define as "smooth saturation", inspired by [13]), rings of fractions ($\mathcal{C}^\infty$-rings of fractions, defined first by I. Moerdijk and G. Reyes in [20]), local rings (local $\mathcal{C}^\infty$-rings), reduced rings ($\mathcal{C}^\infty$-reduced $\mathcal{C}^\infty$-rings) and others. We also state and prove new results, such as ad hoc "Separation Theorems", similar to the ones we find in Commutative Algebra, and a stronger version (Theorem 6) of the Theorem 1.4 of [20], characterizing every $\mathcal{C}^\infty$-ring of fractions. We describe the fundamental concepts of Order Theory for $\mathcal{C}^\infty$-rings, proving that every $\mathcal{C}^\infty$-ring is semi-real, and we prove an important result on the strong interplay between the smooth Zariski spectrum and the real smooth spectrum of a $\mathcal{C}^\infty$-ring.

math.AC↗
arXiv2020

On the order theory for $\mathcal{C}^\infty$-reduced $\mathcal{C}^\infty$-Rings and applications

In the present work we carry on the study of the order theory for ($\mathcal{C}^{\infty}-$-reduced) $\mathcal{C}^{\infty}-$-rings initiated in \cite{rings1} (see also \cite{BM2}). In particular, we apply some results of the order theory of $\mathcal{C}^{\infty}-$-fields (e.g., every such field is real closed) to present another approach to the order theory of general $\mathcal{C}^{\infty}-$-rings: "smooth real spectra" (see \cite{separation}). This suggests that a model-theoretic investigation of the class of $\mathcal{C}^{\infty}-$-fields could be interesting and also useful to provide the first steps towards the development of the "Real Algebraic Geometry" of $\mathcal{C}^{\infty}-$-rings.

math.AC↗
arXiv2019

Formalizing the Curry-Howard Correspondence

The Curry-Howard Correspondence has a long history, and still is a topic of active research. Though there are extensive investigations into the subject, there doesn't seem to be a definitive formulation of this result in the level of generality that it deserves. In the current work, we introduce the formalism of p-institutions that could unify previous aproaches. We restate the tradicional correspondence between typed $λ$-calculi and propositional logics inside this formalism, and indicate possible directions in which it could foster new and more structured generalizations. Furthermore, we indicate part of a formalization of the subject in the programming-language Idris, as a demonstration of how such theorem-proving enviroments could serve mathematical research.

math.LO↗
arXiv2019

An algebraic (set) theory of surreal numbers, I

The notion of surreal number was introduced by J.H. Conway in the mid 1970's: the surreal numbers constitute a linearly ordered (proper) class $No$ containing the class of all ordinal numbers ($On$) that, working within the background set theory NBG, can be defined by a recursion on the class $On$. Since then, have appeared many constructions of this class and was isolated a full axiomatization of this notion that been subject of interest due to large number of interesting properties they have, including model-theoretic ones. Such constructions suggests strong connections between the class $No$ of surreal numbers and the classes of all sets and all ordinal numbers. In an attempt to codify the universe of sets directly within the surreal number class, we have founded some clues that suggest that this class is not suitable for this purpose. The present work, that expounds parts of the PhD thesis of the first author (\cite{Ran18}), establishes a basis to obtain an "algebraic (set) theory for surreal numbers" along the lines of the Algebraic Set Theory - a categorial set theory introduced in the 1990's based on the concept of ZF-algebra: to establish abstract and general links between the class of all surreal numbers and a universe of "surreal sets" similar to the relations between the class of all ordinals ($On$) and the class of all sets ($V$), that also respects and expands the links between the linearly ordered class of all ordinals and of all surreal numbers.

math.CT↗
arXiv2019

On categories of o-minimal structures

Our aim in this paper is to look at some transfer results in model theory (mainly in the context of o-minimal structures) from the category theory viewpoint.

math.LO↗
arXiv2019

Non Reduced Theory of Quadratic Forms Over Rings

Based on the works of M. Marshall on multirings, we propose the fundamentals for a \textbf{non reduced} abstract quadratic forms theory in general coefficients on rings, with the machinery of multirings and multifields.

math.RA↗
arXiv2019

Von Neumann Regular $\mathcal{C}^{\infty}-$Rings and Applications

In this paper we present the notion of a von Neumann regular $\mathcal{C}^{\infty}-$ring, we prove some results about them and we describe some of their properties. We prove, using two different methods, that the category of von Neumann regular $\mathcal{C}^{\infty}-$rings is a reflective subcategory of $\mathcal{C}^{\infty}{\rm \bf Rng}$. We prove that every homomorphism between Boolean algebras can be represented by a $\mathcal{C}^{\infty}-$ring homomorphism between von Neumann regular $\mathcal{C}^{\infty}-$rings.

math.CT↗
arXiv2019

A Universal Algebraic Survey of $\mathcal{C}^{\infty}-$Rings

In this paper we present some basic results of the Universal Algebra of $\mathcal{C}^\infty$-rings which were nowhere to be found in the current literature. The outstanding book of I. Moerdijk and G. Reyes,[24], presents the basic (and advanced) facts about $\mathcal{C}^\infty$-rings, however such a presentation has no universal algebraic "flavour". We have been inspired to describe $\mathcal{C}^\infty$-rings through this viewpoint by D. Joyce in [15]. Our main goal here is to provide a comprehensive material with detailed proofs of many known "taken for granted" results and constructions used in the literature about $\mathcal{C}^\infty$-rings and their applications - such proofs either could not be found or were merely sketched. We present, in detail, the main constructions one can perform within this category, such as limits, products, homomorphic images, quotients, directed colimits, free objects and others, providing a "propaedeutic exposition" for the reader's benefit.

math.RA↗
arXiv2019

Remarks on expansions of the real field: tameness, Hardy fields and smooth rings

In the talk \cite{vandendries-matthias-} presented at Logic and Foundations section of ICM-2018, Rio de Janeiro, the authors analyze, under a model-theoretic perspective, three ways to enrich the real continuum by infinitesimal and infinite quantities. In the present work, we present a first model-theoretic connection of another (but related to the previous one) triple of structures: o-minimal structures, Hardy fields and smooth rings.

math.LO↗
arXiv2018

Classifying toposes for some theories of $\mathcal{C}^{\infty}-$rings

In this paper we present classifying toposes for the following theories: the theory of $\mathcal{C}^{\infty}-$rings, the theory of local $\mathcal{C}^{\infty}-$rings and the theory of von Neumann regular $\mathcal{C}^{\infty}-$rings. The classifying toposes for the first two theories were stated without proof by Ieke Moerdijk and Gonzalo Reyes on the page 366 of \cite{MSIA}, where they assert that the topos ${\rm \bf Set}^{\mathcal{C}^{\infty}{\rm \bf Rng}_{\rm fp}}$ classifies the theory of $\mathcal{C}^{\infty}-$rings and that the smooth Zariski topos classifies the theory of local $\mathcal{C}^{\infty}-$rings.

math.LO↗
arXiv2017

Promiscuously Quadratic Rings

We consider a convenient category of "quadratic" multirings, that allows simple functorial relations with categories associated with abstract quadratic forms theories and shares many good aspects of the theories of Special Groups and of Realsemigroups, but tries to avoids its drawbacks.

math.RA↗
arXiv2017

Some consequences of the Firoozbakht's conjecture

In this paper we present the statement of the Firoozbakht's conjecture, some of its consequences if it is proved and we show a consequence of Zhang's theorem concerning the Firoozbakht's conjecture.

math.NT↗
arXiv2016

An abstract approach to Glivenko's theorem

The aim of this work is to provide a special kind of conservative translation between abstract logics, namely an \textit{abstract Glivenko's theorem}. Firstly we define institutions on the categories of logic, algebraizable logics, and Lindenbaum algebraizable logic. In the sequel, we introduce the notion os Glivenko's context relating two algebraizable logics (respectively, Lindenbaum algebraizable logics) and we prove that for each Glivenko's context can be associated an institutions morphism between the corresponding logical institutions. As a consequence of the existence of such institutions morphisms, we have established abstract versions of Glivenko's theorem between those algebraizable logics (Lindenbaum algebraizable logics), generalizing the results presented in \cite{To}. In particular, considering the institutions of classical logic and of intuitionistic logic, we build a Glivenko's context and thus an abstract Glivenko's theorem that is exactly the traditional Glivenko's theorem. Finally we present a category of algebraizable logic with Glivenko's context as morphisms. We can interpret the results of this work as an evidence of the (virtually unexplored) relevance of institution theory in the study of propositional logic.

math.LO↗