Presentaciones a Congresos

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Learning by knowledge sharing in autonomous intelligent systems
(2006) García Martínez, Ramón; Borrajo, Daniel; Maceri, Pablo; Britos, Paola Verónica
"Very few learning systems applied to problem solving have focused on learning operator definitions from the interaction with a completely unknown environment. In order to achieve better learning convergence, several agents that learn separately are allowed to interchange each learned set of planning operators. Learning is achieved by establishing plans, executing those plans in the environment, analyzing the results of the execution, and combining new evidence with prior evidence. Operators are generated incrementally by combining rote learning, induction, and a variant of reinforcement learning. The results show how allowing the communication among individual learning (and planning) agents provides a much better percentage of successful plans, plus an improved convergence rate than the individual agents alone."
Identification of velocity variations in a seismic cube using neural networks
(2006) Cersósimo, Darío Sergio; Ravazoli, Claudia; García Martínez, Ramón
"This research allow to infer that from seismic section and well data it is possible to determine velocity anomalies variations in layers with thicknesses below to the seismic resolution using neuronal networks."
Conceptualization maturity metrics for expert systems
(2006) Britos, Paola Verónica; García Martínez, Ramón; Hauge, Ødwin
“Metrics used on development of expert systems is not a well investigated problem area. This article suggests some metrics to be used to measure the maturity of the conceptualization process and the complexity of the decision process in the problem domain. We propose some further work to be done with these metrics. Applying those metrics makes new and interesting problems, concerning the structure of knowledge to surface.”
Patterns in temporal series of meteorological variables using SOM & TDIDT
(2006) Cogliati, Marisa; Britos, Paola Verónica; García Martínez, Ramón
"The purpose of the present article is to investigate if there exist any such set of temporal stable patterns in temporal series of meteorological variables studying series of air temperature, wind speed and direction an atmospheric pressure in a period with meteorological conditions involving nocturnal inversion of air temperature in Allen, Rio Negro, Argentina. Our conjecture is that there exist independent stable temporal activities, the mixture of which give rise to the weather variables; and these stable activities could be extracted by Self Organized Maps plus Top Down Induction Decision Trees analysis of the data arising from the weather patterns, viewing them as temporal signals."
Detection of breast lesions in medical digital imaging using neural networks
(2006) Ferrero, Gustavo; Britos, Paola Verónica; García Martínez, Ramón
"The purpose of this article is to present an experimental application for the detection of possible breast lesions by means of neural networks in medical digital imaging. This application broadens the scope of research into the creation of different types of topologies with the aim of improving existing networks and creating new architectures which allow for improved detection."
Prediction in health domain using Bayesian networks optimization based on induction learning techniques
(2006) Felgaer, Pablo; Britos, Paola Verónica; García Martínez, Ramón
"A Bayesian network is a directed acyclic graph in which each node represents a variable and each arc a probabilistic dependency; they are used to provide: a compact form to represent the knowledge and exible methods of reasoning. Obtaining it from data is a learning process that is divided in two steps: structural learning and parametric learning. In this paper we define an automatic learning method that optimizes the Bayesian networks applied to classification, using a hybrid method of learning that combines the advantages of the induction techniques of the decision trees (TDIDT-C4.5) with those of the Bayesian networks. The resulting method is applied to prediction in health domain."
Optimizing relationships information in repertory grids
(2008) Calot, Enrique; Britos, Paola Verónica; García Martínez, Ramón
"The Repertory Grid method is widely used in knowledge engineering to infer functional relationships between constructs given by an expert. The method is ignoring information that could be used to infer more precise dependencies. This paper proposes an improvement to take advantage on the information that is being ignored in the current method. Furthermore, this improvement fixes several other limitations attached to the original method, such as election in a discrete set of two values as a similarity pole or a contrast pole, the arbitrary measurement of distances, the unit-scale dependency and the normalization, among others. The idea is to use linear regression to estimate the correlation between constructs and use the fitness error as a distance measure."
Requirements elicitation in data mining for business intelligence projects
(2008) Britos, Paola Verónica; Dieste, Oscar; García Martínez, Ramón
"There are data mining methodologies for business intelligence (DM-BI) projects that highlight the importance of planning an ordered, documented, consistent and traceable requirement’s elicitation throughout the entire project. However, the classical software engineering approach is not completely suitable for DM-BI projects because it neglects the requirements specification aspects of projects. This article focuses on identifying concepts for understand DM-BI project domain from DM-BI field experience, including how requirements can be educed by a proposed DM-BI project requirements elicitation process and how they can be documented by a template set."
Aggregation languages for moving object and places of interest
(2008) Gómez, Leticia Irene; Kuijpers, Bart; Vaisman, Alejandro Ariel
"We address aggregate queries over GIS data and moving object data, where non-spatial information is stored in a data warehouse. We propose a formal data model and query language to express complex aggregate queries. Next, we study the compression of trajectory data, produced by moving objects, using the notions of stops and moves. We show that stops and moves are expressible in our query language and we consider a fragment of this language, consisting of regular expressions to talk about temporally ordered sequences of stops and moves. This fragment can be used not only for querying, but also for expressing data mining and pattern matching tasks over trajectory data."
RE-SPaM: Using regular expressions for sequential pattern mining in trajectory databases
(2008) Gómez, Leticia Irene; Vaisman, Alejandro Ariel
"In sequential pattern mining, languages based on regular expressions (RE) were proposed to restrict frequent sequences to the ones that satisfy user-specified constraints. In these languages, REs are applied over items. We propose a much powerful language, based on regular expressions, denoted RE-SPaM, where the basic elements are constraints over the attributes of the items. Expressions in this language may include attributes, functions over attributes, and variables. We present the data model, sketch the syntax and semantics of RE-SPaM, a set of examples, and suggest how RE-SPaM can be used in the mining process."
Learning life cycle in autonomous intelligent systems
(2008) Ierache, Jorge; García Martínez, Ramón; De Giusti, Armando
"Autonomous Intelligent Systems (AIS) integrate planning, learning, and execution in a closed loop, showing an autonomous intelligent behavior. A Learning Life Cycle (LLC) Operators, Trained Base Operators and World Interaction Operators. The extension of the original architecture to support the new type of operators is presented."
Work in progress: programming misunderstandings discovering process based on intelligent data mining tools
(2008) Britos, Paola Verónica; Jiménez Rey, Elizabeth; Rodríguez, Darío; García Martínez, Ramón
"We present research work in progress that focuses on data mining tools used for helping teachers to apply a three step knowledge discovering process to diagnose students’ misunderstandings (and their causes) related to their programming errors."
Pedagogical protocols selection automatic assistance
(2008) Britos, Paola Verónica; Cataldi, Zulma; Sierra, Enrique; García Martínez, Ramón
"The preliminary results presented in this paper corresponds to a research project oriented to the search of the relationship between the predilection of students concerning learning style and the pedagogical protocols used by the human tutors (professors during the first courses of the Computer Engineering undergraduate Program) by using intelligent systems tools."
Discovering sensing capability in multi-agent systems
(2010) Parpaglione, María Cristina; Santos, Juan Miguel
"What should be the sensing capabilities of agents in a Multi-Agent System be to solve a problem efficiently, quickly and economicly? This question often appears when trying to solve a problem using Multi-Agent Systems. This paper introduces a method to find these sensing capabilities in order to solve a given problem. To achieve this, the sensing capability of an agent is modeled by a parametrized function and then Genetic Algorithms are used to find the parameters’ values. The individual behavior of the agents are found with Reinforcement Learning."
Complete calculi for structured specifications in fork algebra
(2010) López Pombo, Carlos Gustavo; Frías, Marcelo
"In previous articles we presented Argentum, a tool for reasoning across heterogeneous specifications based on the language of fork algebras. Argentum’s foundations were formalized in the framework of institutions. The formalization made simple to describe a methodology capable of producing a complete system desription from partial views, eventually written in different logical languages. Structured specifications were introduced by Sannella and Tarlecki and extensively studied by Borzyszkowski. The latter also presented conditions under which the calculus for structured specifications is complete. Using fork algebras as a “universal” institution capable of representing expressive logics (such as dynamic and temporal logics), requires using a fork language that includes a reflexive-transitive closure operator. The calculus thus obtained does not meet the conditions required by Borzyszkowski. In this article we present structure building operators (SBOs) over fork algebras, and provide a complete calculus for these operators."
Trajectory sequential patterns with regular expression constraints including spatial queries
(2010-05) Gardella, Pablo; Gómez, Leticia Irene; Vaisman, Alejandro Ariel
"Moving object (MO) data representation and computing have received a fair share of attention over recent years from the database community. Replacing raw trajectory data (i.e., MO positions at different time instants) by sequences of application-dependent stops occurred at so-called places of interest (Pols) leads to the notion of semantic trajectories. Different techniques exist for sequential pattern analysis of trajectories defined in this way. One of them, RE-SPaM, expresses sequential patterns by means of regular expressions built not only over item identifiers, but also over constraints defined on the (temporal and non-temporal) attributes of the items to be analyzed. This analysis could be greatly enriched if spatial and non-spatial data associated with the MO are taken into account. In this paper we show how we can take advantage of the extensibility properties of RE-SPaM to augment its expressive power by allowing to include spatial queries in the constraints. For this, we make use of Piet, a framework allowing to integrate OLAP, GIS and MO data, and its associated query language denoted Piet-QL, providing a link between moving object data and their geographic environment."
Analysis of invariants for efficient bounded verification
(2010-07) Galeotti, Juan Pablo; Rosner, Nicolás; López Pombo, Carlos G.; Frías, Marcelo
"SAT-based bounded veri cation of annotated code consists of translating the code together with the annotations to a propositional formula, and analyzing the formula for speci cation violations using a SAT-solver. If a violation is found, an execution trace exposing the error is exhibited. Code involving linked data structures with intricate invariants is particularly hard to analyze using these techniques. In this article we present TACO, a prototype tool which implements a novel, general and fully automated technique for the SAT-based analysis of JML-annotated Java sequential programs dealing with complex linked data structures. We instrument code analysis with a symmetry-breaking predicate that allows for the parallel, automated computation of tight bounds for Java elds. Experiments show that the translations to propositional formulas require signi cantly less propositional variables, leading in the experiments we have carried out to an improvement on the e ciency of the analysis of orders of magnitude, compared to the non instrumented SAT-based analysis. We show that, in somecases, our tool can uncover bugs that cannot be detected by state-of-the-art tools based on SAT-solving, model checking or SMT-solving."
Incorporating coverage criteria in bounded exhaustive black box test generation of structural inputs
(2011) Aguirre, Nazareno; Bengolea, Valeria; Galeotti, Juan Pablo; Frías, Marcelo
"The automated generation of test cases for heap allocated, complex, structures is particularly difficult. Various state of the art tools tackle this problem by bounded exhaustive exploration of potential test cases, using constraint solving mechanisms based on techniques such as search, model checking, symbolic execution and combinations of these. In this article we present a technique for improving the bounded ex haustive constraint based test case generation of structurally complex inputs, for “filtering” approaches. The technique works by guiding the search considering a given black box test criterion. Such a test criterion is incorporated in the constraint based mechanism so that the exploration of potential test cases can be pruned without missing coverable classes of inputs, corresponding to the test criterion. We present the technique, together with some case studies illustrating its performance for some black box testing criteria. The experimental results associated with these case studies are shown in the context of Korat, a state of the art tool for constraint based test case generation, but the approach is applicable in other contexts using a filtering approach to test generation."
Temporal SOLAP: query language, implementation, and a use case
(2012) Bisceglia, Pablo; Gómez, Leticia Irene; Vaisman, Alejandro Ariel
"The integration of Geographic Information Systems (GIS) and On-Line Analytical Processing (OLAP), denoted SOLAP, is aimed at exploring and analyzing spatial data. In real-world SOLAP applications, spatial and non-spatial data are subject to changes. In this paper we present a temporal query language for SOLAP, called TPiet-QL, supporting so-called discrete changes (for example, in land use or cadastral applications there are situations where parcels are merged or split). TPiet-QL allows expressing integrated GIS-OLAP queries in an scenario where spatial objects change across time. We also present a prototype implementation, and show how this application is used in a real-world scenario: the analysis of protected areas in Uruguay."
Querying semantic web data cubes
(2016) Etcheverry, Lorena; Vaisman, Alejandro Ariel
"We address the problem of querying data cubes for Online Analytical Processing (OLAP) analysis, directly on the Semantic Web (SW). We rst introduce CQL, a simple algebra for querying data cubes at a conceptual level. Taking advantage of QB4OLAP metadata, we automatically translate CQL queries into SPARQL ones, and propose query optimization strategies that adapt, to the particular OLAP set ting, general-purpose techniques. A web application allows exploring and querying OLAP cubes on the SW, using the machinery presented here."

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