In classical propositional logic (CPL) logical reasoning is formalised as logical entailment and can be computed by means of tableau and resolution proof procedures. Unfortunately CPL is not expressive enough and using first order logic (FOL) does not solve the problem either since proof procedures for these logics are not decidable. Modal propositional logics (MPL) on the other hand are both decidable and more expressive than CPL. It therefore seems reasonable to apply tableau and resolution proof systems to MPL in order to compute logical entailment in MPL. Although some of the principles in CPL are present in MPL, there are complexities in MPL that are not present in CPL. Tableau and resolution proof systems which address these issues and others will be surveyed here. In particular the work of Abadi & Manna (1986), Chan (1987), del Cerro & Herzig (1988), Fitting (1983, 1990) and Gore (1995) will be reviewed. / Computing / M. Sc. (Computer Science)

Textual Entailment vise à capturer les principaux besoins d'inférence sémantique dans les applications de Traitement du Langage Naturel. Depuis 2005, dans la Textual Entailment reconnaissance tâche (RTE), les systèmes sont appelés à juger automatiquement si le sens d'une portion de texte, le texte - T, implique le sens d'un autre texte, l'hypothèse - H. Cette thèse nous nous intéressons au cas particulier de l'implication, l'implication de généralité. Pour nous, il ya différents types d'implication, nous introduisons le paradigme de l'implication textuelle en généralité, qui peut être définie comme l'implication d'une peine spécifique pour une phrase plus générale, dans ce contexte, le texte T implication Hypothèse H, car H est plus générale que T.Nous proposons des méthodes sans surveillance indépendante de la langue de reconnaissance de l'implication textuelle par la généralité, pour cela, nous présentons une mesure asymétrique informatif appelée Asymmetric simplifié InfoSimba, que nous combinons avec différentes mesures d'association asymétriques à reconnaître le cas spécifique de l'implication textuelle par la généralité.Cette thèse, nous introduisons un nouveau concept d'implication, les implications de généralité, en conséquence, le nouveau concept d'implications de la reconnaissance par la généralité, une nouvelle orientation de la recherche en Traitement du Langage Naturel. / Textual Entailment aims at capturing major semantic inference needs across applications in Natural Language Processing. Since 2005, in the Textual Entailment recognition (RTE) task, systems are asked to automatically judge whether the meaning of a portion of text, the Text - T, entails the meaning of another text, the Hypothesis - H. This thesis we focus a particular case of entailment, entailment by generality. For us, there are various types of implication, we introduce the paradigm of Textual Entailment by Generality, which can be defined as the entailment from a specific sentence towards a more general sentence, in this context, the Text T entailment Hypothesis H, because H is more general than T. We propose methods unsupervised language-independent for Recognizing Textual Entailment by Generality, for this we present an Informative Asymmetric Measure called the Simplified Asymmetric InfoSimba, which we combine with different asymmetric association measures to recognizingthe specific case of Textual Entailment by Generality.This thesis, we introduce the new concept of implication, implications by generality, in consequence, the new concept of recognition implications by generality, a new direction of research in Natural Language Processing.

[pt] A avaliação sistemática de uma Instituição de Ensino Superior (IES) fornece à sua administração um feedback valioso sobre vários aspectos da vida acadêmica, como a reputação da instituição e o desempenho individual do corpo docente. Em particular, as pesquisas com alunos são uma fonte de informação de primeira mão que ajuda a avaliar o desempenho do professor e a adequação do curso. Os objetivos principais desta tese são criar e avaliar modelos de análise de sentimento dos comentários dos alunos e estratégias para resumir os comentários dos alunos. A tese primeiro descreve duas abordagens para classificar a polaridade dos comentários dos alunos, ou seja, se eles são positivos, negativos ou neutros. A primeira abordagem depende de um dicionário criado manualmente que lista os termos que representam o sentimento a ser detectado nos comentários dos alunos. A segunda abordagem adota um modelo de representação de linguagem, que não depende de um dicionário criado manualmente, mas requer algum conjunto de teste anotado manualmente. Os resultados indicaram que a primeira abordagem superou uma ferramenta de linha de base e que a segunda abordagem obteve um desempenho muito bom, mesmo quando o conjunto de comentários anotados manualmente é pequeno. A tese então explora várias estratégias para resumir um conjunto de comentários com interpretações semelhantes. O desafio está em resumir um conjunto de pequenas frases, escritas por pessoas diferentes, que podem transmitir ideias repetidas. Como estratégias, a tese testou Market Basket Analysis, Topic Models, Text Similarity, TextRank e Entailment, adotando um método de inspeção humana para avaliar os resultados obtidos, uma vez que as métricas tradicionais de sumarização de textos se mostraram inadequadas. Os resultados sugerem que o agrupamento combinado com a estratégia baseada em centróide atinge os melhores resultados. / [en] The systematic evaluation of a Higher Education Institution (HEI) provides its administration with valuable feedback about several aspects of academic life, such as the reputation of the institution and the individual performance of teachers. In particular, student surveys are a first-hand source of information that help assess teacher performance and course adequacy. The primary goals of this thesis are to create and evaluate sentiment analysis models of students comments, and strategies to summarize students comments. The thesis first describes two approaches to classify the polarity of students comments, that is, whether they are positive, negative, or neutral. The first approach depends on a manually created dictionary that lists terms that represent the sentiment to be detected in the students comments. The second approach adopts a language representation model, which does not depend on a manually created dictionary, but requires some manually annotated test set. The results indicated that the first approach outperformed a baseline tool, and that the second approach achieved very good performance, even when the set of manually annotated comments is small. The thesis then explores several strategies to summarize a set of comments with similar interpretations. The challenge lies in summarizing a set of small sentences, written by different people, which may convey repeated ideas. As strategies, the thesis tested Market Basket Analysis, Topic Models, Text Similarity, TextRank, and Entailment, adopting a human inspection method to evaluate the results obtained, since traditional text summarization metrics proved inadequate. The results suggest that clustering combined with the centroid-based strategy achieves the best results.

The claim that a principle known as Irreducible Complexity (IC) is empirically discoverable is investigated successively from the perspective of engineering, then molecular biology and finally theology, with the aim of evaluating the utility of IC for an interdisciplinary dialogue between all three. In the process, IC is subjected to the principle objections presented against it in the literature, leading to the conclusion that IC is sufficiently resistant to scientific criticism to be accepted as a true property of certain living systems. The ubiquity of machine descriptors in the professional literature of molecular biology is scrutinised in the context of the role of metaphor in science, as well as in the context of entailment models. A Biblical Theological approach to the Bible is harnessed to establish a framework for estimating the extent to which the story of Christ warrants expectation of first order design formalisms in nature, and whether that story within itself provides any homomorphic exemplification of IC. Additionally, key theological criticisms of IC are evaluated as well as criticisms of the Neo Darwinian revisioning of the Biblical account. The overall conclusion is that a true interdisciplinary dialogue where IC is the nexus holds theoretical as well as experimental promise. / Thesis (M.A. (Dogmatics))--North-West University, Potchefstroom Campus, 2008.

The claim that a principle known as Irreducible Complexity (IC) is empirically discoverable is investigated successively from the perspective of engineering, then molecular biology and finally theology, with the aim of evaluating the utility of IC for an interdisciplinary dialogue between all three. In the process, IC is subjected to the principle objections presented against it in the literature, leading to the conclusion that IC is sufficiently resistant to scientific criticism to be accepted as a true property of certain living systems. The ubiquity of machine descriptors in the professional literature of molecular biology is scrutinised in the context of the role of metaphor in science, as well as in the context of entailment models. A Biblical Theological approach to the Bible is harnessed to establish a framework for estimating the extent to which the story of Christ warrants expectation of first order design formalisms in nature, and whether that story within itself provides any homomorphic exemplification of IC. Additionally, key theological criticisms of IC are evaluated as well as criticisms of the Neo Darwinian revisioning of the Biblical account. The overall conclusion is that a true interdisciplinary dialogue where IC is the nexus holds theoretical as well as experimental promise. / Thesis (M.A. (Dogmatics))--North-West University, Potchefstroom Campus, 2008.

The claim that a principle known as Irreducible Complexity (IC) is empirically discoverable is investigated successively from the perspective of engineering, then molecular biology and finally theology, with the aim of evaluating the utility of IC for an interdisciplinary dialogue between all three. In the process, IC is subjected to the principle objections presented against it in the literature, leading to the conclusion that IC is sufficiently resistant to scientific criticism to be accepted as a true property of certain living systems. The ubiquity of machine descriptors in the professional literature of molecular biology is scrutinised in the context of the role of metaphor in science, as well as in the context of entailment models. A Biblical Theological approach to the Bible is harnessed to establish a framework for estimating the extent to which the story of Christ warrants expectation of first order design formalisms in nature, and whether that story within itself provides any homomorphic exemplification of IC. Additionally, key theological criticisms of IC are evaluated as well as criticisms of the Neo Darwinian revisioning of the Biblical account. The overall conclusion is that a true interdisciplinary dialogue where IC is the nexus holds theoretical as well as experimental promise. / Thesis (M.A. (Dogmatics))--North-West University, Potchefstroom Campus, 2008.

Étant donnée la masse toujours croissante de texte publié, la compréhension automatique des langues naturelles est à présent l'un des principaux enjeux de l'intelligence artificielle. En langue naturelle, les faits exprimés dans le texte ne sont pas nécessairement tous explicites : le lecteur humain infère les éléments manquants grâce à ses compétences linguistiques, ses connaissances de sens commun ou sur un domaine spécifique, et son expérience. Les systèmes de Traitement Automatique des Langues (TAL) ne possèdent naturellement pas ces capacités. Incapables de combler les défauts d'information du texte, ils ne peuvent donc pas le comprendre vraiment. Cette thèse porte sur ce problème et présente notre travail sur la résolution d'inférences pour la compréhension automatique de texte. Une inférence textuelle est définie comme une relation entre deux fragments de texte : un humain lisant le premier peut raisonnablement inférer que le second est vrai. Beaucoup de tâches de TAL évaluent plus ou moins directement la capacité des systèmes à reconnaître l'inférence textuelle. Au sein de cette multiplicité de l'évaluation, les inférences elles-mêmes présentent une grande variété de types. Nous nous interrogeons sur les inférences en TAL d'un point de vue théorique et présentons deux contributions répondant à ces niveaux de diversité : une tâche abstraite contextualisée qui englobe les tâches d'inférence du TAL, et une taxonomie hiérarchique des inférences textuelles en fonction de leur difficulté. La reconnaissance automatique d'inférence textuelle repose aujourd'hui presque toujours sur un modèle d'apprentissage, entraîné à l'usage de traits linguistiques variés sur un jeu d'inférences textuelles étiquetées. Cependant, les données spécifiques aux phénomènes d'inférence complexes ne sont pour le moment pas assez abondantes pour espérer apprendre automatiquement la connaissance du monde et le raisonnement de sens commun nécessaires. Les systèmes actuels se concentrent plutôt sur l'apprentissage d'alignements entre les mots de phrases reliées sémantiquement, souvent en utilisant leur structure syntaxique. Pour étendre leur connaissance du monde, ils incluent des connaissances tirées de ressources externes, ce qui améliore souvent les performances. Mais cette connaissance est souvent ajoutée par dessus les fonctionnalités existantes, et rarement bien intégrée à la structure de la phrase.Nos principales contributions dans cette thèse répondent au problème précédent. En partant de l'hypothèse qu'un lexique plus simple devrait rendre plus facile la comparaison du sens de deux phrases, nous décrivons une méthode de récupération de passage fondée sur une expansion lexicale structurée et un dictionnaire de simplifications. Cette hypothèse est testée à nouveau dans une de nos contributions sur la reconnaissance d'implication textuelle : des paraphrases syntaxiques sont extraites du dictionnaire et appliquées récursivement sur la première phrase pour la transformer en la seconde. Nous présentons ensuite une méthode d'apprentissage par noyaux de réécriture de phrases, avec une notion de types permettant d'encoder des connaissances lexico-sémantiques. Cette approche est efficace sur trois tâches : la reconnaissance de paraphrases, d'implication textuelle, et le question-réponses. Nous résolvons son problème de passage à l'échelle dans une dernière contribution. Des tests de compréhension sont utilisés pour son évaluation, sous la forme de questions à choix multiples sur des textes courts, qui permettent de tester la résolution d'inférences en contexte. Notre système est fondé sur un algorithme efficace d'édition d'arbres, et les traits extraits des séquences d'édition sont utilisés pour construire deux classifieurs pour la validation et l'invalidation des choix de réponses. Cette approche a obtenu la deuxième place du challenge "Entrance Exams" à CLEF 2015. / With the ever-growing mass of published text, natural language understanding stands as one of the most sought-after goal of artificial intelligence. In natural language, not every fact expressed in the text is necessarily explicit: human readers naturally infer what is missing through various intuitive linguistic skills, common sense or domain-specific knowledge, and life experiences. Natural Language Processing (NLP) systems do not have these initial capabilities. Unable to draw inferences to fill the gaps in the text, they cannot truly understand it. This dissertation focuses on this problem and presents our work on the automatic resolution of textual inferences in the context of machine reading. A textual inference is simply defined as a relation between two fragments of text: a human reading the first can reasonably infer that the second is true. A lot of different NLP tasks more or less directly evaluate systems on their ability to recognize textual inference. Among this multiplicity of evaluation frameworks, inferences themselves are not one and the same and also present a wide variety of different types. We reflect on inferences for NLP from a theoretical standpoint and present two contributions addressing these levels of diversity: an abstract contextualized inference task encompassing most NLP inference-related tasks, and a novel hierchical taxonomy of textual inferences based on their difficulty.Automatically recognizing textual inference currently almost always involves a machine learning model, trained to use various linguistic features on a labeled dataset of samples of textual inference. However, specific data on complex inference phenomena is not currently abundant enough that systems can directly learn world knowledge and commonsense reasoning. Instead, systems focus on learning how to use the syntactic structure of sentences to align the words of two semantically related sentences. To extend what systems know of the world, they include external background knowledge, often improving their results. But this addition is often made on top of other features, and rarely well integrated to sentence structure. The main contributions of our thesis address the previous concern, with the aim of solving complex natural language understanding tasks. With the hypothesis that a simpler lexicon should make easier to compare the sense of two sentences, we present a passage retrieval method using structured lexical expansion backed up by a simplifying dictionary. This simplification hypothesis is tested again in a contribution on textual entailment: syntactical paraphrases are extracted from the same dictionary and repeatedly applied on the first sentence to turn it into the second. We then present a machine learning kernel-based method recognizing sentence rewritings, with a notion of types able to encode lexical-semantic knowledge. This approach is effective on three tasks: paraphrase identification, textual entailment and question answering. We address its lack of scalability while keeping most of its strengths in our last contribution. Reading comprehension tests are used for evaluation: these multiple-choice questions on short text constitute the most practical way to assess textual inference within a complete context. Our system is founded on a efficient tree edit algorithm, and the features extracted from edit sequences are used to build two classifiers for the validation and invalidation of answer candidates. This approach reaches second place at the "Entrance Exams" CLEF 2015 challenge.

abstract: In this thesis, I present two new datasets and a modification to the existing models in the form of a novel attention mechanism for Natural Language Inference (NLI). The new datasets have been carefully synthesized from various existing corpora released for different tasks. The task of NLI is to determine the possibility of a sentence referred to as “Hypothesis” being true given that another sentence referred to as “Premise” is true. In other words, the task is to identify whether the “Premise” entails, contradicts or remains neutral with regards to the “Hypothesis”. NLI is a precursor to solving many Natural Language Processing (NLP) tasks such as Question Answering and Semantic Search. For example, in Question Answering systems, the question is paraphrased to form a declarative statement which is treated as the hypothesis. The options are treated as the premise. The option with the maximum entailment score is considered as the answer. Considering the applications of NLI, the importance of having a strong NLI system can't be stressed enough. Many large-scale datasets and models have been released in order to advance the field of NLI. While all of these models do get good accuracy on the test sets of the datasets they were trained on, they fail to capture the basic understanding of “Entities” and “Roles”. They often make the mistake of inferring that “John went to the market.” from “Peter went to the market.” failing to capture the notion of “Entities”. In other cases, these models don't understand the difference in the “Roles” played by the same entities in “Premise” and “Hypothesis” sentences and end up wrongly inferring that “Peter drove John to the stadium.” from “John drove Peter to the stadium.” The lack of understanding of “Roles” can be attributed to the lack of such examples in the various existing datasets. The reason for the existing model’s failure in capturing the notion of “Entities” is not just due to the lack of such examples in the existing NLI datasets. It can also be attributed to the strict use of vector similarity in the “word-to-word” attention mechanism being used in the existing architectures. To overcome these issues, I present two new datasets to help make the NLI systems capture the notion of “Entities” and “Roles”. The “NER Changed” (NC) dataset and the “Role-Switched” (RS) dataset contains examples of Premise-Hypothesis pairs that require the understanding of “Entities” and “Roles” respectively in order to be able to make correct inferences. This work shows how the existing architectures perform poorly on the “NER Changed” (NC) dataset even after being trained on the new datasets. In order to help the existing architectures, understand the notion of “Entities”, this work proposes a modification to the “word-to-word” attention mechanism. Instead of relying on vector similarity alone, the modified architectures learn to incorporate the “Symbolic Similarity” as well by using the Named-Entity features of the Premise and Hypothesis sentences. The new modified architectures not only perform significantly better than the unmodified architectures on the “NER Changed” (NC) dataset but also performs as well on the existing datasets. / Dissertation/Thesis / Masters Thesis Computer Science 2019

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We discuss two ways of using abduction to explain missing entailments from description logic knowledge bases, one more common, one more unusual, and then have a closer look at how current results/implementations on abduction could be used towards generating such explanations, and what still needs to be done. / This is an extended version of an article submitted to XLoKR 2021.