Constrained Horn Clauses (CHCs) are an intermediate program representation that can be generated by several verification tools, and that can be processed and solved by a number of Horn solvers. One of the main challen...
详细信息
Reasoning on defeasible knowledge is a topic of interest in the area of description logics, as it is related to the need of representing exceptional instances in knowledge bases. In this direction, in our previous wor...
详细信息
Aspect extraction aims to extract fine-grained opinion targets from opinion texts. Recent work has shown that the syntactical approach performs well. In this paper, we show that logic programming, particularly Answer ...
详细信息
Aspect extraction aims to extract fine-grained opinion targets from opinion texts. Recent work has shown that the syntactical approach performs well. In this paper, we show that logic programming, particularly Answer Set programming (ASP), can be used to elegantly and efficiently implement the key components of syntax based aspect extraction. Specifically, the well known double propagation (DP) method is implemented using 8 ASP rules that naturally model all key ideas in the DP method. Our experiment on a widely used data set also shows that the ASP implementation is much faster than a Java-based implementation. Syntactical approach has its limitation too. To further improve the performance of syntactical approach, we identify a set of general words from Word Net that have little chance to be an aspect and prune them when extracting aspects. The concept of general words and their pruning are concisely captured by 10 new ASP rules, and a natural extension of the 8 rules for the original DP method. Experimental results show a major improvement in precision with almost no drop in recall compared with those reported in the existing work on a typical benchmark data set. logic programming provides a convenient and effective tool to encode and thus test knowledge needed to improve the aspect extraction methods so that the researchers can focus on the identification and discovery of new knowledge to improve aspect extraction.
This paper introduces and studies a declarative framework for updating views over indefinite databases. An indefinite database is a database with null values that are represented, following the standard database appro...
详细信息
This paper introduces and studies a declarative framework for updating views over indefinite databases. An indefinite database is a database with null values that are represented, following the standard database approach, by a single null constant. Typically a database is represented by a single set of facts D that model what is known to be true. This paper proposes a model of an indefinite extensional database that is more expressive with respect to the closed-world assumption (CWA) adapted for the setting of indefinite databases (Libkin, 1995, A semantics-based approach to design of query languages for partial information. In Semantics in Databases, vol. 1358 of LNCS, pp. 170-208. Springer;der Meyden, 1998, logical approaches to incomplete information: a survey. In logics for Databases and Information Systems, pp. 307-356. Kluwer Academic Publishers, Norwell, MA, USA). More specifically, in our model, databases are determined by two sets of facts: D representing, as usual, all facts that are true in the database, and E that is meant to represent exceptions to the 'unknown range', i.e. facts that cannot be unknown. Intuitively, unless they are explicitly implied to be true by the first set, the facts specified as exceptions are assumed false. The semantics is given by means of a two-level CWA tailored to the case of indefinite information. The paper characterizes the semantics of indefinite databases in terms of their possible worlds that are obtained by instantiating occurrences of null values by concrete constants and defines several classes of database repairs that realize view-update requests. Most notable is the class of constrained repairs. Constrained repairs change the database 'minimally'and avoid making arbitrary commitments. They narrow down the space of alternative ways to fulfill the view-update request to those that are grounded, in a certain strong sense, in the database, the view and the view-update request.
In many real applications, to reach an agreement between the participants of a dialogue, which can be for instance a negotiation, is not easy. Indeed, there are application domains such as the medical domain where to ...
详细信息
In many real applications, to reach an agreement between the participants of a dialogue, which can be for instance a negotiation, is not easy. Indeed, there are application domains such as the medical domain where to reach a consensus among medical professionals is not feasible and might be even regarded as counterproductive. In this paper, we introduce an approach for expressing qualitative preferences between the goals of a dialogue considering ordered disjunction rules. By applying argumentation semantics and degrees of satisfaction of goals, we introduce the so-called dialogue agreement degree. Moreover, by considering sets of dialogue agreement degrees, we define a lattice of agreement degrees. We argue that a lattice of agreement degrees suggests different approximations between the current state of a dialogue and its aimed goals;hence, a lattice of agreement degrees can help to define different heuristics in the settings of strategic argumentation.
Recent progress in logic programming (e.g. the development of the answer set programming (ASP) paradigm) has made it possible to teach it to general undergraduate and even middle/high school students. Given the limite...
详细信息
Recent progress in logic programming (e.g. the development of the answer set programming (ASP) paradigm) has made it possible to teach it to general undergraduate and even middle/high school students. Given the limited exposure of these students to computer science, the complexity of downloading, installing, and using tools for writing logic programs could be a major barrier for logic programming to reach a much wider audience. We developed onlineSPARC, an online ASP environment with a self-contained file system and a simple interface. It allows users to type/edit logic programs and perform several tasks over programs, including asking a query to a program, getting the answer sets of a program, and producing a drawing/animation based on the answer sets of a program.
Professor Koichi Furukawa, an eminent computer scientist and former Editor-in-Chief of the New Generation Computing journal, passed away on January 31, 2017. His passing was a surprise, and we were all shocked and sad...
详细信息
Professor Koichi Furukawa, an eminent computer scientist and former Editor-in-Chief of the New Generation Computing journal, passed away on January 31, 2017. His passing was a surprise, and we were all shocked and saddened by the news. To remember the deceased, this article reviews the great career and contributions of Professor Koichi Furukawa, focusing on his research activities on the foundation and application of logic programming. Professor Furukawa had both a deep understanding and broad impact on logic programming, and he was always gentle but persistent in articulating its value across a broad spectrum of computer science and artificial intelligence research. This article introduces his research along with its insightful and unique philosophical framework.
The paper deals with base revision for Answer Set programming (ASP). Base revision in classical logic is done by the removal of formulas. Exploiting the non-monotonicity of ASP allows one to propose other revision str...
详细信息
The paper deals with base revision for Answer Set programming (ASP). Base revision in classical logic is done by the removal of formulas. Exploiting the non-monotonicity of ASP allows one to propose other revision strategies, namely addition strategy or removal and/or addition strategy. These strategies allow one to define families of rule-based revision operators. The paper presents a semantic characterization of these families of revision operators in terms of answer sets. This semantic characterization allows for equivalently considering the evolution of syntactic logic programs and the evolution of their semantic content. It then studies the logical properties of the proposed operators and gives complexity results.
Comparative questions in Chinese, as a special and complex form of question answering (QA), have their own unique sentence structure, existing methods cannot solve them well. Inspired by cognitive studies on how human...
详细信息
Comparative questions in Chinese, as a special and complex form of question answering (QA), have their own unique sentence structure, existing methods cannot solve them well. Inspired by cognitive studies on how humans solve complex problems, we propose a hybrid framework which combines logic programming and attention based Bi-LSTM. This framework is decomposed into three consecutive components: 1) identify comparative questions, 2) extract comparative elements from the identified comparative questions, and 3) answer factoid questions containing the extracted comparative elements. Specifically, for the former two components, logic programming is adopted to filter out non-comparative questions and extract comparative elements. For the latter one, a bidirectional long and short term memory (Bi-LSTM) model with attention mechanism is utilized. Experimental results on Chinese geographical question datasets show that our proposed hybrid framework achieves outstanding performance for practical use.
When studying sequent calculi, proof theorists often have to prove properties about the systems, whether to show that they are "well-behaved", amenable to automated proof search, complete with respect to ano...
详细信息
When studying sequent calculi, proof theorists often have to prove properties about the systems, whether to show that they are "well-behaved", amenable to automated proof search, complete with respect to another system, consistent, among other reasons. These proofs usually involve many very similar cases, which leads to authors rarely writing them in full detail, only pointing to one or two more complicated cases. Moreover, the amount of details makes them more error-prone for humans. Computers, on the other hand, are very good at handling details and repetitiveness. In this work we have formalized textbook proofs of the meta-theory of sequent calculi for linear logic in Abella. Using the infrastructure developed, the proofs can be easily adapted to other substructural logics. We implemented rules as clauses in an intuitive and straightforward way, similar to logic programming, using operations on multisets for the explicit contexts. Although the proofs are quite big, they use only elementary reasoning principles, which makes the proof techniques fairly portable to other formal reasoning systems. (C) 2019 Elsevier B.V. All rights reserved.
暂无评论