一种综合的本体相似度计算方法

本体相似度计算是本体映射的关键环节.本体的实例、关系、属性、结构等信息是相似度计算需要考虑的重要因素.针对目前本体映射过程中相似度计算所存在的问题,提出了一种综合的相似度计算方法.首先判断不同本体之间是否存在相关性.若相关,则充分考虑各种相关因素,从语义和概念两个层面来进行比较,然后给出了本体的综合相似度计算方法.最后采用了两组测试数据对该方法进行实验,并与GLUE系统的概率统计方法进行了实验对比.实验结果表明,该方法能够有效确保相似度计算的准确性.     

Critical Configurations for 1-View in Projections from ℙ<Superscript>k</Superscript> → ℙ<Superscript>2</Superscript>

In this paper we describe, from a theoretical point of view, critical configurations for the projective reconstruction of a set of points, for a single view, i.e. for calibration of a camera, in the case of projections from ℙ^k to ℙ² for k ≥ 4. We give first a general result describing these critical loci in ℙ^k, which, if irreducible, are algebraic varieties of dimension k−2 and degree 3. If k=4 they can be either a smooth ruled surface or a cone and if k = 5 they can be a smooth three dimensional variety, ruled in planes, or a cone. If k≥ 6, the variety is always a cone, the vertex of which has dimension at least k − 6. The reducible cases are studied in Appendix A. These results are then applied to determine explicitly the critical loci for the projections from ℙ^k which arise from the dynamic scenes in ℙ³ considered in [13]. Marina Bertolini is currently Associate Professor of Geometry at the Department of Mathematics at the Università degli Studi di Milano, Italy. Her main field of research is Complex Projective Algebraic Geometry, with particular interest for the classification of projective varieties and for the geometry of Grassmann varieties. On these topics M. Bertolini has published more than twenty reviewed papers on national and international journals. She has been for some years now interested also in applications of Algebraic Geometry to Computer Vision problems. Cristina Turrini is Associate Professor of Geometry at the Department of Mathematics of Università degli Studi di Milano, Italy. Her main research interest is Complex Projective Algebraic Geometry: subvarieties of Grassmannians, special varieties, automorphisms, classification. In the last two years she has started to work on applications of Algebraic Geometry to problems of Computer Vision. She is author or co-author of about thirty reviewed papers. She is also involved in popularization of Mathematics, and on this subject she is co-editor of some books.     

基于奇异值分解的中文Ontology自动学习技术

语义Web是一个美好的构想，Ontology在语义Web中起着举足轻重的作用，它不仅能为人类用户而且能为软件agent提供从语法层次到语义层次上的互操作性。目前Web上主要是各种布局的HTML文档，未来的语义Web页面将是各种领域Ontology的实例以及到其它实例上的链接，因此语义Web的成功强烈依赖于Ontology的增殖，方便快捷地构造各领城Ontology是实现语义Web的关健。该文提出一种基于奇异值分解的中文Ontology自动学习技术，这种技术的特点是其简易性以及准确的数学理论基础。     

本体校正的半自动处理过程

创建本体间的映射是个单调冗烦的工作过程,特别是当各本体非常庞大时。从Ontol-ogy的基本理论出发,基于基本概念、角色和关系,探讨了Ontology开发中的各个要素,然后介绍了一种半自动校正处理过程,该过程是在本体校正框架的基础上实现的。由即将被校正的两个本体组成输入处理过程,而输出处理过程则是本体间实体的通信集合。     

Ontology Evolution: Not the Same as Schema Evolution

As ontology development becomes a more ubiquitous and collaborative process, ontology versioning and evolution becomes an important area of ontology research. The many similarities between database-schema evolution and ontology evolution will allow us to build on the extensive research in schema evolution. However, there are also important differences between database schemas and ontologies. The differences stem from different usage paradigms, the presence of explicit semantics and different knowledge models. A lot of problems that existed only in theory in database research come to the forefront as practical problems in ontology evolution. These differences have important implications for the development of ontology-evolution frameworks: The traditional distinction between versioning and evolution is not applicable to ontologies. There are several dimensions along which compatibility between versions must be considered. The set of change operations for ontologies is different. We must develop automatic techniques for finding similarities and differences between versions.     

DOLCE ergo SUMO: On foundational and domain models in the SmartWeb Integrated Ontology (SWIntO)

Increased availability of mobile computing, such as personal digital assistants (PDAs), creates the potential for constant and intelligent access to up-to-date, integrated and detailed information from the Web, regardless of one's actual geographical position. Intelligent question-answering requires the representation of knowledge from various domains, such as the navigational and discourse context of the user, potential user questions, the information provided by Web services and so on, for example in the form of ontologies. Within the context of the SmartWeb project, we have developed a number of domain-specific ontologies that are relevant for mobile and intelligent user interfaces to open-domain question-answering and information services on the Web. To integrate the various domain-specific ontologies, we have developed a foundational ontology, the SmartSUMO ontology, on the basis of the DOLCE and SUMO ontologies. This allows us to combine all the developed ontologies into a single SmartWeb Integrated Ontology (SWIntO) having a common modeling basis with conceptual clarity and the provision of ontology design patterns for modeling consistency. In this paper, we present SWIntO, describe the design choices we made in its construction, illustrate the use of the ontology through a number of applications, and discuss some of the lessons learned from our experiences.     

Characterizing TC<Superscript>0</Superscript> in Terms of Infinite Groups

We characterize the languages in TC⁰ = L(Maj[<,Bit]) and L(Maj[<]) as inverse morphic images of certain groups. Necessarily these are infinite, since nonregular sets are concerned. To limit the power of these infinite algebraic objects, we equip them with a finite type set and introduce the notion of a finitely typed (infinite) monoid. Following this approach we investigate type-respecting mappings and construct a new type of block product that more adequately deals with infinite monoids. We exhibit two classes of finitely typed groups which exactly characterize TC⁰ and L(Maj[<]) via inverse morphisms.     

Ontology matching with semantic verification

Automated Semantic Matching of Ontologies with Verification (ASMOV) is a novel algorithm that uses lexical and structural characteristics of two ontologies to iteratively calculate a similarity measure between them, derives an alignment, and then verifies it to ensure that it does not contain semantic inconsistencies. In this paper, we describe the ASMOV algorithm, and then present experimental results that measure its accuracy using the OAEI 2008 tests, and that evaluate its use with two different thesauri: WordNet, and the Unified Medical Language System (UMLS). These results show the increased accuracy obtained by combining lexical, structural and extensional matchers with semantic verification, and demonstrate the advantage of using a domain-specific thesaurus for the alignment of specialized ontologies.     

Ontology and rule-based natural language processing approach for interpreting textual regulations on underground utility infrastructure

The nation’s massive underground utility infrastructure must comply with a multitude of regulations. The regulatory compliance checking of underground utilities requires an objective and consistent interpretation of the regulations. However, utility regulations contain a variety of domain-specific terms and numerous spatial constraints regarding the location and clearance of underground utilities. It is challenging for the interpreters to understand both the domain and spatial semantics in utility regulations. To address the challenge, this paper adopts an ontology and rule-based Natural Language Processing (NLP) framework to automate the interpretation of utility regulations – the extraction of regulatory information and the subsequent transformation into logic clauses. Two new ontologies have been developed. The urban product ontology (UPO) is domain-specific to model domain concepts and capture domain semantics on top of heterogeneous terminologies in utility regulations. The spatial ontology (SO) consists of two layers of semantics – linguistic spatial expressions and formal spatial relations – for better understanding the spatial language in utility regulations. Pattern-matching rules defined on syntactic features (captured using common NLP techniques) and semantic features (captured using ontologies) were encoded for information extraction. The extracted information elements were then mapped to their semantic correspondences via ontologies and finally transformed into deontic logic (DL) clauses to achieve the semantic and logical formalization. The approach was tested on the spatial configuration-related requirements in utility accommodation policies. Results show it achieves a 98.2% precision and a 94.7% recall in information extraction, a 94.4% precision and a 90.1% recall in semantic formalization, and an 83% accuracy in logical formalization.     

Ontology Integration: Approaches and Challenging Issues

In recent years, the decentralized development of ontologies has led to the generation of multiple ontologies of overlapping knowledge. This heterogeneity problem can be tackled by integrating existing ontologies to build a single coherent one. Ontology integration has been investigated during the last two decades, but it is still a challenging task. In this article, we provide a comprehensive survey of all ontology integration aspects. We discuss related notions and scrutinize existing techniques and literature approaches. We also detail the role of ontology matching in the ontology integration process. Indeed, the ontology community has adopted the splitting of the ontology integration problem into matching, merging and repairing sub-tasks, where matching is a necessary preceding step for merging, and repairing can be included in the matching process or performed separately. Ontology matching and merging systems have become quite proficient, however the trickiest part lies in the repairing step. We also focus on the case of a holistic integration of multiple heterogeneous ontologies, which needs further exploration. Finally, we investigate challenges, open issues, and future directions of the ontology integration and matching areas.     

Efficient retrieval of ontology fragments using an interval labeling scheme

Nowadays very large domain ontologies are being developed in life-science areas like Biomedicine, Agronomy, Astronomy, etc. Users and applications can benefit enormously from these ontologies in very different tasks, such as visualization, vocabulary homogenizing and data classification. However, due to their large size, they are often unmanageable for these applications. Instead, it is necessary to provide small and useful fragments of these ontologies so that the same tasks can be performed as if the whole ontology is being used. In this work we present a novel method for efficiently indexing and generating ontology fragments according to the user requirements. Moreover, the generated fragments preserve relevant inferences that can be made with the selected symbols in the original ontology. Such a method relies on an interval labeling scheme that efficiently manages the transitive relationships present in the ontologies. Additionally, we provide an interval’s algebra to compute some logical operations over the ontology concepts. We have evaluated the proposed method over several well-known biomedical ontologies. Results show very good performance and scalability, demonstrating the applicability of the proposed method in real scenarios.     

本体演化管理研究

自W3C主席TimBerncrs-Lee首先提出了语义web的概念后,它正在成为计算机信息处理领域当前研究的热点之一。本体将在“语义Web”中起到至关重要的作用,它通过定义精确的共享术语,以提供某一特定领域可重用的知识。但是这些知识并不是静态的,而是随着时问的推移不断演化。领域的改变、自适应不同的任务、或概念模型的改变都要求本体的变更。随着本体开发变成一个泛化的、协同的过程,本体版本控制和演化管理已成为本体研完中一个重要的领域。本文首先对本体演化的原因和所带来的问题进行分析,然后讨论了本体演化管理的关键技术,着重强调了Web上本体标识和本体变化机制的定义,并对今后的研究工作进行了展望。     

Ontology matching benchmarks: Generation,stability, and discriminability

The OAEI Benchmark test set has been used for many years as a main reference to evaluate and compare ontology matching systems. However, this test set has barely varied since 2004 and has become a relatively easy task for matchers. In this paper, we present the design of a flexible test generator based on an extensible set of alterators which may be used programmatically for generating different test sets from different seed ontologies and different alteration modalities. It has been used for reproducing Benchmark both with the original seed ontology and with other ontologies. This highlights the remarkable stability of results over different generations and the preservation of difficulty across seed ontologies, as well as a systematic bias towards the initial Benchmark test set and the inability of such tests to identify an overall winning matcher. These were exactly the properties for which Benchmark had been designed. Furthermore, the generator has been used for providing new test sets aiming at increasing the difficulty and discriminability of Benchmark. Although difficulty may be easily increased with the generator, attempts to increase discriminability proved unfruitful. However, efforts towards this goal raise questions about the very nature of discriminability.     

Solving Connected Dominating Set Faster than 2<Superscript><Emphasis Type="Italic">n</Emphasis></Superscript>

In the connected dominating set problem we are given an n-node undirected graph, and we are asked to find a minimum cardinality connected subset S of nodes such that each node not in S is adjacent to some node in S. This problem is also equivalent to finding a spanning tree with maximum number of leaves. Despite its relevance in applications, the best known exact algorithm for the problem is the trivial Ω(2 ⁿ ) algorithm that enumerates all the subsets of nodes. This is not the case for the general (unconnected) version of the problem, for which much faster algorithms are available. Such a difference is not surprising, since connectivity is a global property, and non-local problems are typically much harder to solve exactly. In this paper we break the 2 ⁿ barrier, by presenting a simple O(1.9407 ⁿ ) algorithm for the connected dominating set problem. The algorithm makes use of new domination rules, and its analysis is based on the Measure and Conquer technique. An extended abstract of this paper appeared in the proceedings of FSTTCS’06. Fedor V. Fomin was additionally supported by the Research Council of Norway.     

Aondê: An ontology Web service for interoperability across biodiversity applications

Biodiversity research requires associating data about living beings and their habitats, constructing sophisticated models and correlating all kinds of information. Data handled are inherently heterogeneous, being provided by distinct (and distributed) research groups, which collect these data using different vocabularies, assumptions, methodologies and goals, and under varying spatio-temporal frames. Ontologies are being adopted as one of the means to alleviate these heterogeneity problems, thus helping cooperation among researchers. While ontology toolkits offer a wide range of operations, they are self-contained and cannot be accessed by external applications. Thus, the many proposals for adopting ontologies to enhance interoperability in application development are either based on the use of ontology servers or of ontology frameworks. The latter support many functions, but impose application recoding whenever ontologies change, whereas the first supports ontology evolution, but for a limited set of functions.This paper presents Aondê—a Web service geared towards the biodiversity domain that combines the advantages of frameworks and servers, supporting ontology sharing and management on the Web. By clearly separating storage concerns from semantic issues, the service provides independence between ontology evolution and the applications that need them. The service provides a wide range of basic operations to create, store, manage, analyze and integrate multiple ontologies. These operations can be repeatedly invoked by client applications to construct more complex manipulations. Aondê has been validated for real biodiversity case studies.     

An O(2<Superscript>O(k)</Superscript>n<Superscript>3</Superscript>) FPT Algorithm for the Undirected Feedback Vertex Set Problem

We describe an algorithm for the Feedback Vertex Set problem on undirected graphs, parameterized by the size k of the feedback vertex set, that runs in time O(c^kn³) where c = 10.567 and n is the number of vertices in the graph. The best previous algorithms were based on the method of bounded search trees, branching on short cycles. The best previous running time of an FPT algorithm for this problem, due to Raman, Saurabh and Subramanian, has a parameter function of the form 2^{O(k log k /log log k)}. Whether an exponentially linear in k FPT algorithm for this problem is possible has been previously noted as a significant challenge. Our algorithm is based on the new FPT technique of iterative compression. Our result holds for a more general form of the problem, where a subset of the vertices may be marked as forbidden to belong to the feedback set. We also establish "exponential optimality" for our algorithm by proving that no FPT algorithm with a parameter function of the form O(2^o(k)) is possible, unless there is an unlikely collapse of parameterized complexity classes, namely FPT = M[1].     

Ontology design with a granular approach

Ontology design for complex applications is quite a challenge. The quality of an ontology is highly dependent upon the capabilities of designers, and the collaborative design process is hampered by the difficulty of balancing the viewpoints of different designers. In this paper, we present a granular view of ontology: ontologies are granular, ontologies are granular approximations of conceptualizations and conceptual-relation granules of an ontology are ordered tuples. We then propose a corresponding granular ontology design approach. In our granular ontology design approach, the unified granular cognition level and hierarchies of sub-concepts are initialized before ontological terms are designed in detail, which reduces the subjective effects of the capabilities of designers. Our approach also introduces the idea of optimization to choose an optimal subset, which can best approximate the real concept domain, from the knowledge rule set presented by different domain experts. The optimal subset is chosen on the basis of the principle of granular ontology knowledge structure.     

Differential Attack on Five Rounds of the SC2000 Block Cipher<Superscript>*</Superscript>

The SC2000 block cipher has a 128-bit block size and a user key of 128,192 or 256 bits,which employs a total of 6.5 rounds if a 128-bit user key is used.It is a CRYPTREC recommended e-government cipher in Japan.In this paper we address how to recover the user key from a few subkey bits of SC2000,and describe two 4.75-round differential characteristics with probability 2-126 of SC2000 and seventy-six 4.75-round differential characteristics with probability 2-127.Finally,we present a differential cryptanalysis attack on a 5-round reduced version of SC2000 when used with a 128-bit key;the attack requires 2-125.68 chosen plaintexts and has a time complexity of 2 125.75 5-round SC2000 encryptions.The attack does not threat the security of the full SC2000 cipher,but it suggests for the first time that the safety margin of SC2000 with a 128-bit key decreases below one and a half rounds.