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Claudio Gutierrez

Publications and source records attributed to Claudio Gutierrez.

At least 19 recordsLinked to original sources
arXiv2026

Multiset semantics in SPARQL, Relational Algebra and Datalog

The paper analyzes and characterizes the algebraic and logical structure of the multiset semantics for SPARQL patterns involving AND, UNION, FILTER, EXCEPT, and SELECT. To do this, we align SPARQL with two well-established query languages: Datalog and Relational Algebra. Specifically, we study (i) a version of non-recursive Datalog with safe negation extended to support multisets, and (ii) a multiset relational algebra comprising projection, selection, natural join, arithmetic union, and except. We prove that these three formalisms are expressively equivalent under multiset semantics.

cs.DB↗
arXiv2026

On the Meaning of the Web as an Object of Study

This text advances the hypothesis that the meaning of the Web as an object of study has diluted as a clear research domain. One example of this phenomenon is the identity crisis of the Web Conference and the International Semantic Web Conference. At its root is the Web's evolution from a focused technological object into a universal digital environment, a transition whose very success has fragmented its academic community and obscured its core identity. We chart this trajectory from a well-defined object of study to a fragmented backdrop, identifying key pressures such as the "academic tragedy of the commons" and the disruptive force of AI. We conclude that a fundamental community discussion is needed to define what it means to study the Web now that it has become the universal infrastructure for global digital activity.

cs.CY↗
arXiv2023

A Copernican Revolution in Data

Half a century ago, Charles Bachman foresaw the significance and centrality of data in the digital world. In this short paper, we delve into the evolution of these ideas within the database community over the past decades. We believe that this historical analysis helps deepen our comprehension of the fundamental changes undergoing our discipline and provides insights into the future trajectory of our field.

cs.DB↗
arXiv2022

Educational Tools for Mapuzugun

Mapuzugun is the language of the Mapuche people. Due to political and historical reasons, its number of speakers has decreased and the language has been excluded from the educational system in Chile and Argentina. For this reason, it is very important to support the revitalization of the Mapuzugun in all spaces and media of society. In this work we present a tool towards supporting educational activities of Mapuzugun, tailored to the characteristics of the language. The tool consists of three parts: design and development of an orthography detector and converter; a morphological analyzer; and an informal translator. We also present a case study with Mapuzugun students showing promising results. Short Abstract in Mapuzuzgun: Tüfachi küzaw pegelfi kiñe zugun küzawpeyüm kelluaetew pu mapuzugun chillkatufe kimal kizu tañi zugun.

cs.CL↗
arXiv2021

Knowledge Graphs

In this paper we provide a comprehensive introduction to knowledge graphs, which have recently garnered significant attention from both industry and academia in scenarios that require exploiting diverse, dynamic, large-scale collections of data. After some opening remarks, we motivate and contrast various graph-based data models and query languages that are used for knowledge graphs. We discuss the roles of schema, identity, and context in knowledge graphs. We explain how knowledge can be represented and extracted using a combination of deductive and inductive techniques. We summarise methods for the creation, enrichment, quality assessment, refinement, and publication of knowledge graphs. We provide an overview of prominent open knowledge graphs and enterprise knowledge graphs, their applications, and how they use the aforementioned techniques. We conclude with high-level future research directions for knowledge graphs.

cs.AI↗
arXiv2021

Querying in the Age of Graph Databases and Knowledge Graphs

Graphs have become the best way we know of representing knowledge. The computing community has investigated and developed the support for managing graphs by means of digital technology. Graph databases and knowledge graphs surface as the most successful solutions to this program. The goal of this document is to provide a conceptual map of the data management tasks underlying these developments, paying particular attention to data models and query languages for graphs.

cs.DB↗
arXiv2018

The Problem of Correlation and Substitution in SPARQL -- Extended Version

Implementations of a standard language are expected to give same outputs to identical queries. In this paper we study why different implementations of SPARQL (Fuseki, Virtuoso, Blazegraph and rdf4j) behave differently when evaluating queries with correlated variables. We show that at the core of this problem lies the historically troubling notion of logical substitution. We present a formal framework to study this issue based on Datalog that besides clarifying the problem, gives a solid base to define and implement nesting.

cs.LO↗
arXiv2017

An introduction to Graph Data Management

A graph database is a database where the data structures for the schema and/or instances are modeled as a (labeled)(directed) graph or generalizations of it, and where querying is expressed by graph-oriented operations and type constructors. In this article we present the basic notions of graph databases, give an historical overview of its main development, and study the main current systems that implement them.

cs.DB↗
arXiv2017

Organic Visualization of Document Evolution

Recent availability of data of writing processes at keystroke-granularity has enabled research on the evolution of document writing. A natural step is to develop systems that can actually show this data and make it understandable. Here we propose a data structure that captures a document's fine-grained history and an organic visualization that serves as an interface to it. We evaluate a proof-of-concept implementation of the system through a pilot study with documents written by students at a public university. Our results are promising and reveal facets such as general strategies adopted, local edition density and hierarchical structure of the final text.

cs.HC↗
arXiv2017

G-CORE: A Core for Future Graph Query Languages

We report on a community effort between industry and academia to shape the future of graph query languages. We argue that existing graph database management systems should consider supporting a query language with two key characteristics. First, it should be composable, meaning, that graphs are the input and the output of queries. Second, the graph query language should treat paths as first-class citizens. Our result is G-CORE, a powerful graph query language design that fulfills these goals, and strikes a careful balance between path query expressivity and evaluation complexity.

cs.DB↗
arXiv2016

The multiset semantics of SPARQL patterns

The paper determines the algebraic and logic structure of the multiset semantics of the core patterns of SPARQL. We prove that the fragment formed by AND, UNION, OPTIONAL, FILTER, MINUS and SELECT corresponds precisely to both, the intuitive multiset relational algebra (projection, selection, natural join, arithmetic union and except), and the multiset non-recursive Datalog with safe negation.

cs.DB↗
arXiv2016

Correlation and Substitution in SPARQL

In the current SPARQL specification the notion of correlation and substitution are not well defined. This problem triggers several ambiguities in the semantics. In fact, implementations as Fuseki and Virtuoso assume different semantics. In this technical report, we provide a semantics of correlation and substitution following the classic philosophy of substitution and correlation in logic, programming languages and SQL. We think this proposal not only fix the current ambiguities and problems, but helps to set a safe formal base to further extensions of the language. This work is part of an ongoing work of Daniel Hernandez. These anomalies in the W3C Specification of SPARQL 1.1 were detected early and reported no later than 2014, when two erratas were registered (cf. https://www.w3.org/2013/sparql-errata#errata-query-8 and https://www.w3.org/2013/sparql-errata#errata-query-10).

cs.DB↗
arXiv2016

Negation in SPARQL

This paper presents a thorough study of negation in SPARQL. The types of negation supported in SPARQL are identified and their main features discussed. Then, we study the expressive power of the corresponding negation operators. At this point, we identify a core SPARQL algebra which could be used instead of the W3C SPARQL algebra. Finally, we analyze the negation operators in terms of their compliance with elementary axioms of set theory.

cs.DB↗
arXiv2016

Group Centrality for Semantic Networks: a SWOT analysis featuring Random Walks

Group centrality is an extension of the classical notion of centrality for individuals, to make it applicable to sets of them. We perform a SWOT (strengths, weaknesses, opportunities and threats) analysis of the use of group centrality in semantic networks, for different centrality notions: degree, closeness, betweenness, giving prominence to random walks. Among our main results stand out the relevance and NP-hardness of the problem of finding the most central set in a semantic network for an specific centrality measure.

cs.SI↗
arXiv2015

Conferences vs. Journals: Throwing the baby out with the bath water?

Criticism of the conference model should be put in context. Evidences suggest that the essential features of this model have emerged as responses to challenges posed by current trends of scientific research and the impact of the new techno-economic paradigm, the age of Information and Communication Technology. This context seems indispensable when discussing today's problems of scientific evaluation, in particular the Conference vs. Journal (CvJ) debate. This debate, also, would benefit from systematic historical and sociological studies of these practices. In this note we briefly develop these arguments.

cs.DL↗
arXiv2014

Carlos Grandjot. Drei Jahrzehnte der Mathematik in Chile: 1930-1960

Carlos Grandjot (1900-1979) was a German mathematician, doctorate from Göttingen, who moved to Chile in 1929 and developed there his life and career. He was influential in the development of Chilean mathematics during the period 1930 to 1960. This article reports our investigation of his biography and describes the mathematical environment in his new homeland.

math.HO↗
arXiv2013

Web Maps and Their Algebra

A map is an abstract visual representation of a region, taken from a given space, usually designed for final human consumption. Traditional cartography focuses on the mapping of Euclidean spaces by using some distance metric. In this paper we aim at mapping the Web space by leveraging its relational nature. We introduce a general mathematical framework for maps and an algebra and discuss the feasibility of maps suitable for interpretation not only by humans but also by machines.

cs.DL↗