Volume 14, 1995, No. 5


Genetic Algorithms and Trees. Part II: Strategy Trees (The Variable Width Case)

K. Robeys, H. van Hove, A. Verschoren

 

Comparison of Several Error-Free Algorithms to Solve Vandermonde Systems

M. Morháč

Abstract. The paper presents a comparative study of three error-free algorithms to solve Vandermonde system of linear equations.  We propose new iterative error-free algorithm to solve Vandermonde system of linear equations. Any of the methods does not introduce either roundoff errors or errors caused by finite length of computer word into the solution.  However the cost analysis of the methods results in favour of the proposed iterative algorithm.

 

Some Observations on the Minimal Armstrong Relations for Normalised Relation Schemes

J. Demetrovics, Vu Duc Thi

Abstract. For functional dependency second normal form (2NF), third normal form (3NF) and Boyse-Codd normal form (BCNF) which were introduced by E.F. Codd have been widely investigated both theoretically and practically. It is known [6] that a set of minimal keys of a relation scheme is a Sperner system (sometimes it is called an antichain) and for an arbitrary Sperner system there exists a relation scheme the set of minimal keys of which is exactly this Sperner system. This paper gives new necessary and sufficient conditions for an arbitrary relation scheme is in 2NF, 3NF, BCNF and its set of minimal keys is a given Sperner system. Based on these characterizations we present some new estimations for the size of minimal Armstrong relations for 3NF and BCNF relation schemes. We show that given a Sperner system K and BCNF relation scheme s a set of minimal keys of which is K, the number of antikeys (maximal nonkeys) of K is polynomial in the number of attributes iff so is the size of minimal Armstrong relation of s.

 

Investigating the Use of Actors for Computer Vision Applications

F. Arcelli, M. de Santo, M. Di Santo, A. Picariello

Abstract. In this paper, we outline an investigation of actor model features by means of the realization of programs solving significant problems. Our aim is to define some initial ideas about a parallel object/oriented programming framework for computer vision, in which all relative aspects can be addressed. Therefore, in the paper we describe an initial experiment of writing parallel code for solving a complex computer vision problem: the segmentation of cursive script characters. Through this task we want to show how an application programmer can express the different kinds of parallelism present in the problem, emphasizing the advantages obtained by the use of the actor model, both from the concurrency and the object-oriented design points of view. The programs have been written by means of a simple but powerful notation which we introduced with the aim of deeply investigating and testing actor model characteristics and as a core for the realization of an actor based high-level language.

 

A Brief Survey on Control Strategies in Pattern Analysis

J. Kepka

Abstract. All the useful information available must be usually utilized to recognize complex patterns with required accuracy and speed. The crucial problem which has to be repeatedly solved is to find the sophisticated strategy of utilizing this information for pattern analysis. This paper can be considered to be an extension of the paper [4] written by Nagao which appeared in Pattern Recognition Journal. The conventional strategies are only briefly reviewed, the new hierarchical strategies based on attributed hierarchical description systems and the knowledge-based strategies to pattern analysis are discussed in more detail.

 

I-Path Analysis

J. Blatný, Z. Kotásek

Abstract. In this paper a circuit at the register transfer level will be denoted as an RTL circuit. The paper describes a method for extracting the RTL circuit structure from the circuit formal description, the I-path concept is used. The way of representing the RTL circuit structure by labelled directed graph where nodes represent components and primary inputs/outputs and arcs represent connections between them is presented. Labels identifying the component type are attached to nodes, other labels are also attached to arcs to identify attributes of connections. It is shown how the graph theory algorithms can be used to derive the information about the accessibility of circuit components, i.e. the existence of I-paths between them, and the sequences of control and clock signals which must be generated to transfer an information along the existing I-paths.


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