9845111
Quantitative Agent Service Matching
The ultimate goal of service matching is to find the service provider(s) that would perform tasks of given description with the best overall degree of satisfaction. However, service description matching solves only part of the problem. Agents that match a given request may vary greatly in their actual capabilities to perform the tasks, and an agent may have strong and weak areas. In this work, we take a quantitative approach in which performance rating is considered an integral part of an agent's capability model and service distribution is taken into account in determining the degree of match. With the dynamic refinement of the agent capability model, the broker captures an agent's performance levels as well as its strong and weak areas. An experimental system has been designed and implemented within the OWL/OWL-S framework and the results statistics show significant advantage over other major levels of brokers.
9863446
ITTALKS: An Application of Agents in the Semantic Web
Effective use of the vast quantity of information now available on the web will require the use of "Semantic Web" markup languages such as the DARPA Agent Markup Language (DAML). Such languages will enable the automated gathering and processing of much information that is currently available but insufficiently utilized. Effectively, such languages will facilitate the integration of multi-agent systems with the existing information infrastructure. As part of our exploration of SemanticWeb technology, and DAML in particular, we have constructed ITTALKS, a web-based system for automatic and intelligent notification of information technology talks. In this paper, we describe the ITTALKS system, and discuss the numerous ways in which the use of Semantic Web concepts and DAML extend its ability to provide an intelligent online service to both the human community and the agents assisting them.
15167056
Swoogle: Searching for Knowledge on the Semantic Web
Swoogle is an implemented system that discovers, analyzes and indexes knowledge encoded in semantic web documents on the Web. Swoogle reasons about these documents and their constituent parts (e.g., terms and triples) and records meaningful metadata about them. Swoogle provides webscale semantic web data access service, which helps human users and software systems to find relevant documents, terms and triples, via its search and navigation services. Swoogle also provides a customizable algorithm inspired by Google's PageRank algorithm but adapted to the semantics and use patterns found in semantic web documents.
1962537
Finding and Ranking Knowledge on the Semantic Web
Swoogle helps software agents and knowledge engineers find Semantic Web knowledge encoded in RDF and OWL documents on the Web. Navigating such a Semantic Web on the Web is difficult due to the paucity of explicit hyperlinks beyond the namespaces in URIrefs and the few inter-document links like rdfs:seeAlso and owl:imports. In order to solve this issue, this paper proposes a novel Semantic Web navigation model providing additional navigation paths through Swoogle's search services such as the Ontology Dictionary. Using this model, we have developed algorithms for ranking the importance of Semantic Web objects at three levels of granularity: documents, terms and RDF graphs. Experiments show that Swoogle outperforms conventional web search engine and other ontology libraries in finding more ontologies, ranking their importance, and thus promoting the use and emergence of consensus ontologies.
18308344
Using Colored Petri Nets for Conversation Modeling
Conversations are a useful means of structuring communicative interactions among agents. The value of a conversation-based approach is largely determined by the conversational model it uses. Finite State Machines, used heavily to date for this purpose, are not sufficient for complex agent interactions requiring a notion of concurrency. We propose the use of Colored Petri Nets as a model underlying a language for conversation specification. This carries the relative simplicity and graphical representation of the former approach, along with greater expressive power and support for concurrency. The construction of such a language, Protolingua, is currently being investigated within the framework of the Jackal agent development environment. In this paper, we explore the use of Colored Petri Nets in modeling agent communicative interaction.
183316
Modifying Bayesian Networks by Probability Constraints
This paper deals with the following problem: modify a Bayesian network to satisfy a given set of probability constraints by only change its conditional probability tables, and the probability distribution of the resulting network should be as close as possible to that of the original network. We propose to solve this problem by extending IPFP (iterative proportional fitting procedure) to probability distributions represented by Bayesian networks. The resulting algorithm E-IPFP is further developed to D-IPFP, which reduces the computational cost by decomposing a global E-IPFP into a set of smaller local E-IPFP problems. Limited analysis is provided, including the convergence proofs of the two algorithms. Computer experiments were conducted to validate the algorithms. The results are consistent with the theoretical analysis.
11039476
On the chromatic uniqueness of certain bipartite graphs
Let K(p, q), p ⩽ q, denote the complete bipartite graph in which the two partite sets consist of p and q vertices, respectively. We denote by K-r(p, q), the family of all graphs obtained by deleting any r distinct edges from K(p, q). Teo and Koh showed that K-1(p, q) is chromatically unique (in short χ-unique) for all p, q such that 3 ⩽ p ⩽ q. In this paper, we obtain a sufficient condition for a graph in K-2(p, q) to be χ-unique. Using this result, we then prove that each graph in K-2(p, p + d) is χ-unique for p ⩾ 4and 0 ⩽ d ⩽ 3. For d ⩾ 4, the graphs in K-2(p, q + d) are χ-unique if p > (A + √B)/4d2, where A and B are polynomials in d. We also show that each graph (≇K(4, 4) – K(1, 3)) in K-3(p, p + d) is χ-unique, for p ⩾ 4 and d=0, 1; and all graphs in K-3(p, p + 2) are χ-unique if and only if all graphs in K-4(p + 1, p + 1) are χ-unique, where p ⩾ 4. Finally we prove that every graph in K-4(p, p + 1) is χ-unique for p ⩾ 5.
5372255
Holes in Graphs
The celebrated Regularity Lemma of Szemeredi asserts that every sufficiently large graph $G$ can be partitioned in such a way that most pairs of the partition sets span $\epsilon$-regular subgraphs. In applications, however, the graph $G$ has to be dense and the partition sets are typically very small. If only one $\epsilon$-regular pair is needed, a much bigger one can be found, even if the original graph is sparse. In this paper we show that every graph with density $d$ contains a large, relatively dense $\epsilon$-regular pair. We mainly focus on a related concept of an $(\epsilon,\sigma)$-dense pair, for which our bound is, up to a constant, best possible.
17089555
Counting Small Cliques in 3-uniform Hypergraphs
Many applications of Szemeredi's Regularity Lemma for graphs are based on the following counting result. If ${\mathcal G}$ is an $s$-partite graph with partition $V({\mathcal G}) =\bigcup_{i=1}^{s} V_i$, $\vert V_i\vert =m$ for all $i\in [s]$, and all pairs $(V_i, V_j)$, $1\leq i < j\leq s$, are $\epsilon$-regular of density $d$, then $\mathcal{G}$ contains $(1\pm f(\epsilon))d^{({s\atop 2})}m^s$ cliques $K_{s}$, provided $\epsilon<\epsilon(d)$, where $f(\epsilon)$ tends to 0 as $\epsilon$ tends to 0.Guided by the regularity lemma for 3-uniform hypergraphs established earlier by Frankl and Rodl, Nagle and Rodl proved a corresponding counting lemma. Their proof is rather technical, mostly due to the fact that the ‘quasi-random’ hypergraph arising after application of Frankl and Rodl's regularity lemma is ‘sparse’, and consequently difficult to handle.When the ‘quasi-random’ hypergraph is ‘dense’ Kohayakawa, Rodl and Skokan (J. Combin. Theory Ser. A 97 307–352) found a simpler proof of the counting lemma. Their result applies even to $k$-uniform hypergraphs for arbitrary $k$. While the Frankl–Rodl regularity lemma will not render the dense case, in this paper, for $k=3$, we are nevertheless able to reduce the harder, sparse case to the dense case.Namely, we prove that a ‘dense substructure’ randomly chosen from the ‘sparse $\delta$-regular structure’ is $\delta$-regular as well. This allows us to count the number of cliques (and other subhypergraphs) using the Kohayakawa–Rodl–Skokan result, and provides an alternative proof of the counting lemma in the sparse case. Since the counting lemma in the dense case applies to $k$-uniform hypergraphs for arbitrary $k$, there is a possibility that the approach of this paper can be adopted to the general case as well.
21181741
An alternative estimation method for the accelerated failure time frailty model
Frailty models based on the proportional hazards model are useful to analyze correlated or clustered failure time data. However, there has been some recent interest in a frailty model based on the popular accelerated failure time model for correlated failure time data ([Pan, W., 2001. Using frailties in the accelerated failure time model. Lifetime Data Anal. 7(1), 55-64], for example). In this paper we review recent advances on this model in the literature. We propose a general estimation method based on M-estimators and the EM algorithm to estimate the parameters in the model. To evaluate the performance of the proposed method, we carry out a simulation study. The results of the simulation study show that the proposed method performs well in comparison with existing estimation methods. As an illustration, the model and the proposed method are applied to analyze the effects of sublingual nitroglycerin and oral isosorbide dinitrate on angina pectoris of coronary heart disease patients [Danahy, D.T., Burwell, D.T., Aronow, W.S., Prakash, R., 1977. Sustained hemodynamic and antianginal effect of high dose oral isosorbide dinitrate. Circulation 55, 381-387].
14722098
TCS-Chord: An Improved Routing Algorithm to Chord Based on the Topology-aware Clustering in Self-organizing Mode
The study on semantic routing efficiency of DHTP2P networks is a key element to promote the development of P2P networks, it is critical for a P2P routing algorithm to be aware of the network physical topology, which leads to improvement of the routing efficiency. By analyzing the Hashing function's properties, some novel logical connections are presented among the destination node, the Chord semantic routing relay node sequence, and the ID of clustering neighbor nodes. This paper describes TCS-Chord (an improved routing algorithm to Chord based on the Topology-aware Clustering in Self-organizing mode) to improve the efficiency of Chord routing. Since the clustering nodes only have local views in the self-organizing mode, some rules are applied for a node to learn other nodes' physical topology-aware locations. The TCS-Chord's routing algorithm is described completely, and our experiments also indicate that TCS-Chord can improve the Chord semantic routing efficiently.