42745
The chromaticity of s-bridge graphs and related graphs
Abstract The graph consisting of s paths joining two vertices is called s -bridge graph. In this paper, we discuss the chromaticity of some families of s -bridge graphs, especially 4-bridge graphs, and some graphs related to s -bridge graphs.
2551506
Chromatic Equivalence Classes of Certain Generalized Polygon Trees, II
Let P(G) denote the chromatic polynomial of a graph G. Two graphs G and H are chromatically equivalent, if P(G)=P(H). A set of graphs S is called a chromatic equivalence class if for any graph H that is chromatically equivalent with a graph G in S, then [email protected]?S. Peng et al. (Discrete Math. 172 (1997) 103-114), studied the chromatic equivalence classes of certain generalized polygon trees. In this paper, we continue that study and present a solution to Problem 2 in Koh and Teo (Discrete Math. 172 (1997) 59-78).
33972996
Chromatic equivalence classes of certain cycles with edges
Abstract Let P(G) denote the chromatic polynomial of a graph G . Two graphs G and H are chromatically equivalent, written G∼H , if P(G)=P(H) . A graph G is chromatically unique if for any graph H , G∼H implies that G is isomorphic with H . In this paper, we give the necessary and sufficient conditions for a family of generalized polygon trees to be chromatically unique.
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.
6604689
Chromaticity of certain tripartite graphs identified with a path
For a graph G, let P(G) be its chromatic polynomial. Two graphs G and H are chromatically equivalent if P(G)=P(H). A graph G is chromatically unique if P(H)=P(G) implies that [email protected]?G. In this paper, we classify the chromatic classes of graphs obtained from K"2","2","[email protected]?P"m(m>=3), (K"2","2","2-e)@?P"m(m>=5) and (K"2","2","2-2e)@?P"m(m>=6) by identifying the end-vertices of the path P"m with any two vertices of K"2","2","2, K"2","2","2-e and K"2","2","2-2e, respectively, where e and 2e are, respectively, an edge and any two edges of K"2","2","2. As a by-product of this, we obtain some families of chromatically unique and chromatically equivalent classes of graphs.
42292049
Fitting semiparametric cure models
Survival data with a sizable cure fraction are commonly encountered in some cancer clinical researches and the semiparametric proportional hazards cure model has been recently investigated to analyze such data. However the estimation method of the model requires a special C program. The restrictive assumptions of the model also limit its application in broader settings. We present a new computational method for the cure model in this article. The method combines the computational methods for logistic regression and the Cox proportional hazards models and is easy to implement in many statistical packages. We also show how this method allows a number of useful extensions of the model to relax the restrictive assumptions. An illustrative example with survival times of lymphoma patients is provided.
723568
A Bayesian Network Approach to Ontology Mapping
This paper presents our ongoing effort on developing a principled methodology for automatic ontology mapping based on BayesOWL, a probabilistic framework we developed for modeling uncertainty in semantic web. In this approach, the source and target ontologies are first translated into Bayesian networks (BN); the concept mapping between the two ontologies are treated as evidential reasoning between the two translated BNs. Probabilities needed for constructing conditional probability tables (CPT) during translation and for measuring semantic similarity during mapping are learned using text classification techniques where each concept in an ontology is associated with a set of semantically relevant text documents, which are obtained by ontology guided web mining. The basic ideas of this approach are validated by positive results from computer experiments on two small real-world ontologies.
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.
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.
16963632
Agents Making Sense of the Semantic Web
Effective use of the vast quantity of available information and services on the Internet will require multi-agent systems to be tightly integrated with existing web infrastructure. This however will be impossible unless the information on the web is presented in a semantic language, such as the DARPA Agent Markup Language (DAML), which is one aim of the “Semantic Web”. As part of our exploration of Semantic Web 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, more interestingly, the agents assisting them.