Raul Fervari

Raul Fervari
National Scientific and Technical Research Council | conicet

PhD in Computing Science

About

43
Publications
3,257
Reads
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362
Citations
Citations since 2016
32 Research Items
333 Citations
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2016201720182019202020212022020406080
2016201720182019202020212022020406080
Introduction
I am currently a researcher at Logics, Interaction and Intelligent Systems group (LIIS) at FaMAF, UNC, Argentina, supported by CONICET. I work in computational aspects of modal logics, in particular my doctoral work was about dynamic logics. My interests include currently: - the study of proof methods for logics combining operators from modal and separation logics - the modelling of different kinds of knowledge in epistemic logic - computational aspects of logics with data comparisons.
Additional affiliations
June 2017 - present
National University of Cordoba, Argentina
Position
  • Professor
August 2016 - December 2016
National University of San Juan
Position
  • Visitor Professor
Description
  • Graduate course: "Introduction to Computational Complexity"
February 2016 - February 2016
23rd Argentinean Summer School in Informatics RIO 2016
Position
  • Lecturer
Description
  • Course: "LogicS: A Modern Perspective" (in spanish)
Education
June 2010 - March 2014
National University of Cordoba, Argentina
Field of study
  • Computational Logic
February 2005 - April 2010
Universidad Nacional de Río Cuarto
Field of study
  • Software Verification

Publications

Publications (43)
Article
Full-text available
Default Logics are a family of non-monotonic formalisms having so-called defaults and extensions as their common foundation. Traditionally, default logics have been defined and dealt with via syntactic notions of consequence in propositional or first-order logic. Here, we build default logics on modal logics. First, we present these default logics...
Chapter
Full-text available
We approach the concept of Pivotal Rule Consequence (PRC) proposed in [14, 15] from a semantical perspective, resorting to model updates in Public Announcement Logic (PAL) [17]. In doing this, we take inspiration from the notion of dynamic consequence from [3, 6]. Our perspective gains in interest since PRC serves as a “bridge” from Classical Logic...
Conference Paper
Full-text available
We study a family of modal logics interpreted on tree-like structures, and featuring local quantifiers ∃^k p that bind the proposition p to worlds that are accessible from the current one in at most k steps. We consider a first-order and a second-order semantics for the quantifiers, which enables us to relate several well-known formalisms, such as...
Article
Full-text available
In this article, we present a modal logic that extends the basic modal logic ML with two dynamic operators: copy (cp), which replicates the current model, labelling each copy with a different propositional symbol and respecting accessibility relations even between distinct copies; and remove (rm), which deletes paths in the model that satisfy certa...
Article
Full-text available
In this paper we introduce sound and strongly complete axiomatizations for XPath with data constraints extended with hybrid operators. First, we present HXPath=, a multi-modal version of XPath with data, extended with nominals and the hybrid operator @. Then, we introduce an axiomatic system for HXPath=, and we prove it is strongly complete with re...
Article
Full-text available
We introduce a new semantics for a multi-agent epistemic operator of knowing how, based on an indistinguishability relation between plans. Our proposal is, arguably, closer to the standard presentation of knowing that modalities in classical epistemic logic. We study the relationship between this semantics and previous approaches, showing that our...
Preprint
Full-text available
We introduce a new semantics for a multi-agent epistemic operator of knowing how, based on an indistinguishability relation between plans. Our proposal is, arguably, closer to the standard presentation of knowing that modalities in classical epistemic logic. We study the relationship between this semantics and previous approaches, showing that our...
Article
Full-text available
Modal separation logics are formalisms that combine modal operators to reason locally, with separating connectives that allow to perform global updates on the models. In this work, we design Hilbert-style proof systems for the modal separation logics MSL(∗,〈!=〉) andMSL(∗,〈〉), where ∗ is the separating conjunction,〈〉is the standard modal operator an...
Article
As a new type of epistemic logics, the logics of knowing how capture the high-level epistemic reasoning about the knowledge of various plans to achieve certain goals. Existing work on these logics focuses on axiomatizations; this paper makes the first study of their model theoretical properties. It does so by introducing suitable notions of bisimul...
Article
Full-text available
Over the last years, the study of logics that can update a model while evaluating a formula has gained in interest. Motivated by many examples in practice such as hybrid logics, separation logics and dynamic epistemic logics, the ability to update a model has been investigated from a more general point of view. In this work, we formalize and verify...
Chapter
Full-text available
Default Logic refers to a family of formalisms designed to carry out non-monotonic reasoning over a monotonic logic (in general, Classical First-Order or Propositional Logic). Traditionally, default logics have been defined and dealt with via syntactic consequence relations. Here, we introduce a family of default logics defined over modal logics. F...
Preprint
We investigate the expressivity and computational complexity of two modal logics on finite forests equipped with operators to reason on submodels. The logic ML(|) extends the basic modal logic ML with the composition operator | from static ambient logic, whereas ML(*) contains the separating conjunction * from separation logic. Though both operator...
Conference Paper
Full-text available
We study the expressivity and complexity of two modal logics interpreted on finite forests and equipped with standard modalities to reason on submodels. The logic ML(C) extends the modal logic K with the composition operator C from ambient logic, whereas ML(∗) features the separating conjunction ∗ from separation logic. Both operators are second-or...
Preprint
Full-text available
In this paper we introduce sound and strongly complete axiomatizations for XPath with data constraints extended with hybrid operators. First, we present HXPath=, a multi-modal version of XPath with data extended with nominals and the hybrid operator @. Then, we introduce an axiomatic system for HXPath=, and we prove it is strongly complete with res...
Chapter
Full-text available
Over the last years, the study of logics that can modify a model while evaluating a formula has gained in interest. Motivated by many examples in practice such as hybrid logics, separation logics and dynamic epistemic logics, the ability of updating a model has been investigated from a more general point of view. In this work, we formalize and veri...
Article
Full-text available
We introduce a modal separation logic MSL whose models are memory states from separation logic and the logical connectives include modal operators as well as separating conjunction and implication from separation logic. With such a combination of operators, some fragments of MSL can be seen as genuine modal logics whereas some others capture standa...
Chapter
Full-text available
We build a Default Logic variant on Intuitionistic Propositional Logic and develop a sound, complete, and terminating, tableaux calculus for it. We also present an implementation of the calculus. We motivate and illustrate the technical elements of our work with examples.
Preprint
Full-text available
Often, we assume that an action is permitted simply because it is not explicitly forbidden; or, similarly, that an action is forbidden simply because it is not explicitly permitted. This kind of assumptions appear, e.g., in autonomous computing systems where decisions must be taken in the presence of an incomplete set of norms regulating a particul...
Article
Full-text available
Often, we assume that an action is permitted simply because it is not explicitly forbidden; or, similarly, that an action is forbidden simply because it is not explicitly permitted. This kind of assumptions appear, e.g., in autonomous computing systems where decisions must be taken in the presence of an incomplete set of norms regulating a particul...
Article
Full-text available
This work studies positive and negative introspection not as ‘static’ properties an agent might or might not have, but rather as epistemic actions that change the agent’s knowledge. The proposed actions include not only operations for achieving full introspection (first with respect to all formulas, and then with respect to a particular χ), but als...
Conference Paper
Full-text available
Modal separation logics are formalisms that combine modal operators to reason locally, with separating connectives that allow to perform global updates on the models. In this work, we design Hilbert-style proof systems for the modal separation logics MSL(*,D) and MSL(*,<>), where * is the separating conjunction, <> is the standard modal operator an...
Chapter
Full-text available
We investigate interpolation and Beth definability in default logics. To this end, we start by defining a general framework which is sufficiently abstract to encompass most of the usual definitions of a default logic. In this framework a default logic \(\mathscr {D}\mathfrak {L}\) is built on a base, monotonic, logic \(\mathfrak {L}\). We then inve...
Article
Full-text available
Relation-changing modal logics (RC for short) are extensions of the basic modal logic with dynamic operators that modify the accessibility relation of a model during the evaluation of a formula. These languages are equipped with dynamic modalities that are able e.g. to delete, add and swap edges in the model, both locally and globally. We study the...
Chapter
Full-text available
Relation-changing modal logics are extensions of the basic modal logic that allow to change the accessibility relation of a model during the evaluation of a formula. In particular, they are equipped with dynamic modalities that are able to delete, add and swap edges in the model, both locally and globally. We investigate the satisfiability problem...
Chapter
Full-text available
This work studies positive and negative introspection not as properties, but rather as actions that change the agent’s knowledge. The actions are introduced as model update operations, with matching modalities expressing their effects. Sound and complete axiom systems are provided, and some properties are explored.
Conference Paper
Full-text available
We provide a sound, complete and terminating tableau procedure to check satisfiability of downward XPath\(_=\) formulas enriched with nominals and satisfaction operators. The calculus is inspired by ideas introduced to ensure termination of tableau calculi for certain Hybrid Logics. We prove that even though we increased the expressive power of XPa...
Conference Paper
Full-text available
In this paper, we propose a single-agent logic of goal-directed knowing how extending the standard epistemic logic of knowing that with a new knowing how operator. The semantics of the new operator is based on the idea that knowing how to achieve phi means that there exists a (uniform) strategy such that the agent knows that it can make sure phi. W...
Article
Full-text available
We give sound and complete axiomatizations for XPath with data tests by ‘equality’ or ‘inequality’, and containing the single ‘child’ axis. This data-aware logic predicts over data trees, which are tree-like structures whose every node contains a label from a finite alphabet and a data value from an infinite domain. The language allows us to compar...
Article
In this paper, we propose a single-agent logic of goal-directed knowing how extending the standard epistemic logic of knowing that with a new knowing how operator. The semantics of the new operator is based on the idea that knowing how to achieve $\phi$ means that there exists a (uniform) strategy such that the agent knows that it can make sure $\p...
Conference Paper
Full-text available
In this paper we introduce a sound and complete axiomatization for XPath with data constraints extended with hybrid operators. First, we define HXPath=(↑↓), an extension of vertical XPath with nominals and the hybrid operator @. Then, we introduce an axiomatic system for HXPath=(↑↓), and we prove it is complete with respect to the class of abstract...
Conference Paper
Full-text available
Relation-changing modal logics are extensions of the basic modal logic that allow changes to the accessibility relation of a model during the evaluation of a formula. In particular, they are equipped with dynamic modalities that are able to delete, add, and swap edges in the model, both locally and globally. We provide translations from these logic...
Technical Report
Full-text available
We give sound and complete axiomatizations for XPath with data tests by "equality" or "inequality", and containing the single "child" axis. This data-aware logic predicts over data trees, which are tree-like structures whose every node contains a label from a finite alphabet and a data value from an infinite domain. The language allows us to compar...
Article
Full-text available
We study dynamic modal operators that can change the accessibility relation of a model during the evaluation of a formula. In particular, we extend the basic modal language with modalities that are able to delete, add or swap an edge between pairs of elements of the domain. We define a generic framework to characterize this kind of operations. Firs...
Article
We propose a logic with the dynamic modal operators copy and remove. The copy operator replicates a given model, and the remove operator removes paths in a given model. We show that the product update by an action model in dynamic epistemic logic decomposes in copy and remove operations, when we consider action models with Boolean preconditions and...
Conference Paper
Full-text available
We propose a logic with the dynamic modal operators copy and remove. The copy operator replicates a given model, and the remove operator removes paths in a given model. We show that the product update by an action model (with Boolean pre-conditions) in dynamic epistemic logic decomposes in copy and remove operations. We also show that copy and remo...
Conference Paper
Full-text available
We propose a logic with the dynamic modal operators copy and remove. The copy operator replicates a given model, and the remove operator removes paths in a given model. We show that the product update by an action model (with Boolean pre-conditions) in dynamic epistemic logic decomposes in copy and remove operations. We also show that copy and remo...
Article
Full-text available
We investigate dynamic modal operators that can change the model during evaluation. We define the logic S S L L by extending the basic modal language with the modality, which is a diamond operator that in addition has the ability to invert pairs of related elements in the domain while traversing an edge of the accessibility relation. S S L L is ver...
Thesis
Full-text available
In this thesis we study dynamic modal operators that can change the model during the evaluation of a formula. In particular, we extend the basic modal language with modalities that are able to swap, delete or add pairs of related elements of the domain. We call the resulting logics Relation-Changing Modal Logics. We study local version of the opera...
Conference Paper
Full-text available
We consider dynamic modal operators that can change the relation of a model during the evaluation of a formula. In this paper, we extend the basic modal language with modalities that are able to delete, add or swap pairs of related elements of the domain; and explore tableau calculi as satisfiability procedures for these logics.
Conference Paper
Full-text available
In this paper we discuss ideas about dynamic modal logics. Modal logics are appropriate to describe properties of relational structures, and several operators have been already introduced to describe dynamic properties of such structures. However, we are interested in those operators which can modify models during the evaluation of a formula. First...
Article
Full-text available
Modal logics are appropriate to describe properties of graphs. But usually these are static properties. We investigate dynamic modal operators that can change the model during evaluation. We define the logic SL by extending the basic modal language with the ♦ modality, which is a diamond operator that has the ability to invert pairs of related elem...
Conference Paper
Full-text available
We study dynamic modal operators that can change the model during the evaluation of a formula. In particular, we extend the basic modal language with modalities that are able to swap, delete or add pairs of related elements of the domain, while traversing an edge of the accessibility relation. We study these languages together with the sabotage mod...
Article
Full-text available
DynAlloy is an extension to the Alloy specification language suitable for modeling properties of executions of software systems. Dy-nAlloy provides fully automated support for verifying properties of pro-grams, in the style of the Alloy Analyzer, i.e., by exhaustively searching for counterexamples of properties in bounded scenarios (bounded do-main...

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Projects (4)
Project
Separation logic has been introduced as an extension of Hoare-Floyd logic to verify programs with mutable data structures. A major feature is to be able to reason locally in a modular way, which can be performed thanks to the separating conjunction (∗) that allows one to state properties in disjoint parts of the memory. In this project, we wish to present new results about decidability, complexity and expressive power of various problems connected with this logic.
Project
Investigate logical aspects of XPath
Project
Investigate the behaviour of dynamic modal logics