DSSim-ontology mapping with uncertainty

This paper introduces an ontology mapping system that is used with a multi agent ontology mapping framework in the context of question answering. Our mapping algorithm incorporates the Dempster Shafer theory of evidence into the mapping process in order to improve the correctness of the mapping. Our main objective was to assess how applying the belief function can improve correctness of the ontology mapping through combining the similarities which were originally created by both syntactic and semantic similarity algorithms. We carried out experiments with the data sets of the Ontology Alignment Evaluation Initiative 2006 which served as a test bed to assess both the strong and weak points of our system. The experiments confirm that our algorithm performs well with both concept and property names

Descubrimiento automático de mappings

Dentro de la problemática de la integración de información, los elementos claves son los mappings, unidades que relacionan las diferentes representaciones (ontologías, bases de datos, redes semánticas, etc. ). Y dentro de toda la colección de operaciones que los mappings llevan asociadas en todo su ciclo de vida, el cuello de botella se encuentra en su descubrimiento. Con este trabajo doctoral se pretende dar un paso más en este campo realizando un nuevo modelo de mappings lo menos limitado, y a la vez funcional, posible a diferentes representaciones y lo más versátil para la combinación de técnicas de descubrimiento, de toda índole, ya existentes y de nuevo cuño de manera automática, basándose en un sistema experto previamente construido a costa de evaluaciones sobre casos de uso reales

Comparison of ontology alignment systems across single matching task via the McNemar's test

Ontology alignment is widely-used to find the correspondences between different ontologies in diverse fields.After discovering the alignments,several performance scores are available to evaluate them.The scores typically require the identified alignment and a reference containing the underlying actual correspondences of the given ontologies.The current trend in the alignment evaluation is to put forward a new score(e.g., precision, weighted precision, etc.)and to compare various alignments by juxtaposing the obtained scores. However,it is substantially provocative to select one measure among others for comparison.On top of that, claiming if one system has a better performance than one another cannot be substantiated solely by comparing two scalars.In this paper,we propose the statistical procedures which enable us to theoretically favor one system over one another.The McNemar's test is the statistical means by which the comparison of two ontology alignment systems over one matching task is drawn.The test applies to a 2x2 contingency table which can be constructed in two different ways based on the alignments,each of which has their own merits/pitfalls.The ways of the contingency table construction and various apposite statistics from the McNemar's test are elaborated in minute detail.In the case of having more than two alignment systems for comparison, the family-wise error rate is expected to happen. Thus, the ways of preventing such an error are also discussed.A directed graph visualizes the outcome of the McNemar's test in the presence of multiple alignment systems.From this graph, it is readily understood if one system is better than one another or if their differences are imperceptible.The proposed statistical methodologies are applied to the systems participated in the OAEI 2016 anatomy track, and also compares several well-known similarity metrics for the same matching problem

Automatic Normalization and Annotation for Discovering Semantic Mappings

Schema matching is the problem of finding relationships among concepts across heterogeneous data sources (heterogeneous in format and in structure). Starting from the “hidden meaning” associated to schema labels (i.e. class/attribute names) it is possible to discover relationships among the elements of different schemata. Lexical annotation (i.e. annotation w.r.t. a thesaurus/lexical resource) helps in associating a “meaning” to schema labels. However, accuracy of semi-automatic lexical annotation methods on real-world schemata suffers from the abundance of non-dictionary words such as compound nouns and word abbreviations. In this work, we address this problem by proposing a method to perform schema labels normalization which increases the number of comparable labels. Unlike other solutions, the method semi-automatically expands abbreviations and annotates compound terms, without a minimal manual effort. We empirically prove that our normalization method helps in the identification of similarities among schema elements of different data sources, thus improving schema matching accuracy

Dealing with uncertain entities in ontology alignment using rough sets

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2012 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.Ontology alignment facilitates exchange of knowledge among heterogeneous data sources. Many approaches to ontology alignment use multiple similarity measures to map entities between ontologies. However, it remains a key challenge in dealing with uncertain entities for which the employed ontology alignment measures produce conflicting results on similarity of the mapped entities. This paper presents OARS, a rough-set based approach to ontology alignment which achieves a high degree of accuracy in situations where uncertainty arises because of the conflicting results generated by different similarity measures. OARS employs a combinational approach and considers both lexical and structural similarity measures. OARS is extensively evaluated with the benchmark ontologies of the ontology alignment evaluation initiative (OAEI) 2010, and performs best in the aspect of recall in comparison with a number of alignment systems while generating a comparable performance in precision

Um modelo para suporte ao raciocínio diagnóstico diante da dinâmica do conhecimento sobre incertezas

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia e Gestão do Conhecimento, Florianópolis, 2013A Engenharia do Conhecimento recorre a abordagens transdisciplinares objetivando oferecer soluções às demandas sociais, destacando-se, artefatos para suporte à decisão. A tomada de decisão humana pode ser de magnitude tão complexa que a atividade intensiva em conhecimento realizada pelo especialista demande assistência proveniente de modelos elaborados por uma visão sistêmica do engenheiro do conhecimento no espaço da solução. O problema desta pesquisa emerge da atividade do especialista médico em Classificação de Risco Metabólico em crianças e adolescentes. As variáveis deste cenário e o processo de classificação apresentam incertezas, manifestadas por causalidade e imprecisão. Redes Bayesianas são empregadas no suporte a classificação cujas variáveis que representam o conhecimento são de natureza probabilística. Contudo, o método bayesiano clássico, diante do fator imprecisão, pode convergir para resultados não qualificados em conformidade àqueles obtidos pelo raciocínio clínico. Por outro lado, Redes Fuzzy-Bayesianas aprimoraram o modelo clássico para suportar inferência sobre conceitos ambíguos. Esta pesquisa contribuiu com o desenvolvimento de um modelo de inferência fuzzy-bayesiano para variáveis não-dicotômicas oferecendo suporte ao raciocínio médico num cenário complexo cuja dinâmica da imprecisão é caracterizada por um tipo de superposição conceitual. Essencialmente dispõe de formalismo matemático modificando a equação do Teorema de Bayes, introduzindo qualificadores difusos para lidar com a imprecisão. Para verificar o modelo utilizou-se de simulações aplicadas sobre dados reais de prontuários. Os resultados obtidos mostraram-se convergentes com a interpretação do especialista e a característica notável foi à qualidade destes resultados nos intervalos próximos aos pontos de corte utilizados pelos especialistas e reproduzidos pelo método bayesiano clássico, problema este que não releva a imprecisão. O modelo distribuiu as probabilidades das hipóteses diagnósticas acompanhando a dinâmica inerente a imprecisão das evidências. Este efeito mostra que um paciente, mesmo que de modo gradual, pode estar evoluindo para um cenário de risco metabólico. O modelo é propenso de ser acoplado a metodologias da Engenharia do Conhecimento e sua implementação pode gerar uma ferramenta aliada à prática do diagnóstico clínico. Abstract : The Knowledge Engineering uses transdisciplinary approaches aiming to provide solutions to social demands, especially, artifacts for decision support. The human decision making can be so complex that the magnitude knowledge intensive activity undertaken by specialist demande assistance from models developed by a systemic view of the knowledge engineer in the solution space. The problem of this research emerges from the activity of the specialist physician in Metabolic Risk Rating in children and adolescents. The variables of this scenario and the classification process is uncertain, expressed by causality and imprecision. Bayesian networks are employed to support the classification whose variables representing knowledge are probabilistic in nature. However, the classical Bayesian method, given the uncertainty factor can converge to results unskilled in accordance to those obtained by clinical reasoning. On the other hand, improved Bayesian Networks Fuzzy-classical model to support inference about ambiguous concepts. This research contributed to the development of a fuzzy-Bayesian inference for non-dichotomous variables supporting the medical reasoning in a complex scenario whose dynamics of vagueness is characterized by a kind of conceptual overlay. Essentially offers mathematical formalism modifying the equation of Bayes Theorem, introducing fuzzy qualifiers to deal with imprecision. To verify the model we used simulations applied to real data from medical records. The results obtained were convergent with interpretation specialist and notable feature was the quality of these results in the ranges near the cutoff points used by experts and reproduced by classical Bayesian method, a problem that does not excuse the inaccuracy. The distributed model the odds of diagnostic hypotheses tracking the dynamics inherent imprecision of the evidence. This effect shows that a patient, even if gradually, may be evolving into a scenario of metabolic risk. The model is likely to be coupled to the Knowledge Engineering methodologies and their implementation can generate a tool coupled with the practice of clinical diagnosis