Ma Shaohan

A practical propositional knowledge base revision algorithm

This paper gives an outline of knowledge base revision and some recently presented complexity results about propositional knowledge base revision. Different methods for revising propositional knowledge base have been proposed recently by several researchers, but all methods are intractable in the general case. For practical application, this paper presents a revision method for special case, and gives its corresponding polynomial algorithm.

Maximal-clique partitions of interval graphs

Abstract It is shown that if an interval graph possesses a maximal-clique partition then its clique coveringand clique partition numbers are equal, and equal to the maximal-clique partition number.Moreover an interval graph has such a partition if and only if all its maximal cliques areedge-disjoint .1980 Mathematics subject classification (Amer. Math. Soc): 05 C 35. 1. Interval graphs and clique-matricesThroughout this paper graphs are finite, undirected, loopless and without mul-tiple edges. A clique is a complete subgraph, and a maximal clique is a cliquewhich is not a proper subgraph of any other clique.A graph G is called an interval graph if its vertices can be put into one-to-onecorrespondence with a set of intervals 7 of the real line, such that two verticesare connected by an edge of G if and only if the corresponding intervals havenonempty intersection. Clearly any induced subgraph of an interval graph is aninterval graph.The earliest characterization of interval graphs was obtained by Lekkerkerkerand Boland [3], as follows.

An efficient parallel graph edge matching algorithm and its applications

A fast and efficient parallel algorithm for finding a maximal edge matching in an undirected graphG(V,E) is proposed. It runs inO(logn) time with (M/logn+n) processors on an EREW PRAM for a class of graph set II, wheren=|V|, m=|E| and II includes at least (i) planar graphs; (ii) graphs of bounded genus; and (iii) graphs of bounded maximum degree and so on. Our algorithm improves the previously known best algorithms by a factor of logn in the time complexity with linear number of processors on EREW PRAMs when the input is limited to II.

Routing protocols for transmitting large databases or multi-databases systems

Most knowledgeable people agree that networking and routing technologies have been around about 25 years. Routing is simultaneously the most complicated function of a network and the most important. It is of the same kind that more than 70% of computer application fields are MIS applications. So the challenge in building and using a MIS in the network is developing the means to find, access, and communicate large databases or multi-databases systems. Because general databases are not time continuous, in fact, they can not be streaming, so we can’t obtain reliable and secure quality of service by deleting some unimportant datagrams in the databases transmission. In this article, we will discuss which kind of routing protocol is the best type for large databases or multi-databases systems transmission in the networks.

Hardness and methods to solve CLIQUE

This paper briefly reviews NP-hard optimization problems and theirin approximability. The hardness of solving CLIQUE problem isspecifically discussed. A dynamic-programming algorithm and its improvedversion for CLIQUE are reviewed and some additional analysis ispresented. The analysis implies that the improved algorithm, HEWN(hierarchical edge-weighted network), only provides a heuristic oruseful method, but cannot be called a polynomial algorithm.The paper briefly reviews NP-hard optimization problems and their inapproximability. The hardness of solving CLIQUE problem is specifically discussed. A dynamic-programming algorithm and its improved version for CLIQUE are reviewed and some additional analysis is presented. The analysis implies that the improved algorithm, HEWN (hierarchical edge-weighted network), only provides a heuristic or useful method, but cannot be called a polynomial algorithm.

A parallel algorithm for generating multiple ordering spanning trees in undirected weighted graphs

In this paper, we propose an efficient parallel algorithm for generatingk (k≥1) spanning trees of a connected, weighted and undirected graphG(V,E,W) in the order of increasing weight. It runs inO(Tmat(n)+k logn) time withO(n2/logn) processors on a CREW PRAM, wheren=|V|, m=|E| andTmat (n),O(logn)≤Tmat (n)≤O(log2n) is the run time of the fastest parallel allel algorithm for finding a minimum spanning tree (MST) of G on a CREW PRAM. SinceTmat (n)=O(log2n) for the time being, our algorithm is of the same time bound withTmat (n) whenk≤O(logn).

The upper limit of the stability of delay-type cellular neural networks

This paper gives an improved sufficient condition of ensuring the stability of delayed cellular neural networks (DCNN) by means of the analysis of a correspondent Lyapunov function. This result improved the limit given by Civalleri and gives an optional upper limit of the stability of DCNN.

Shortest paths computation of graph by neural networks in real time

A new kind of neural networks on solving shortest paths problem is presented, and the stability of the neural networks is proved. For a directed or undirected graph, the proposed neural network is always convergent to its single equilibrium, so that the shortest paths between every pair of nodes of the oriented graph are produced. This paper makes a new study on solving the optimization but not NP-hard problems by neural networks.

An efficient distributed algorithm for game tree search

This paper presents a distributed game tree search algorithm called DDS*. Based on communication overhead, storage requirement, speed up, and other factors, the performance of algorithm DDS* is analysed, and the number of nodes searched with SSS* as well as a-b algorithm. The simulation test shows that DDS* is an efficient and practical search algorithm.