Volume 16, 1997, No. 3


A Regular Folding Procedure

M. Gušev, D.J. Evans

Abstract. Folding transformations on processor arrays result in smaller processor arrays, more efficient work for the processing elements, a decrease in I/O time, pipelineable implementations and circular data flow are presented in [1]. In this paper the folding transformation is defined via symmetric transformations and interlocking translations implemented on the space time graphs. The regular folding transformation according to a translated line of symmetry offers valid and regular solutions. Two generalized procedures for regular folding are given here keep the complexity of the data communications, the processor operations, the regular data flow and avoid data collision. The matrix vector multiplication algorithm is given as an example of the proposed procedures and the best folding transformation is determined.

The efficiency analysis shows that the implementation obtained utilizes the processor array with double efficiency. Moreover, by using the same processor array, problems with double the dimension can be solved. Also, the circular data flow can be used for cascaded algorithms.

 

Generalized Semi-Markov Process Model of Asynchronous Automatic Assembly System with Simultaneous Resource Possession Property, the statement of the perturbation analysis algorithm

M. Valent, Z. Lovász

Abstract. In this paper we will construct the base of generated semi-Markov process (GSMP) model of asynchronous automatic assembly system (AAAS) with simultaneous resource possession (SRP) property, and perturbation analysis (PA) algorithm corresponding to the system.

 

On Planar Affine Transform Determination

G. Podhájecký, J. Glasa

Abstract. An effective direct method for determination of planar affine transform coefficients is described. It is based on construction of triangles defined by barycentric centroids of corresponding parts of reference and transformed images which are cut by straight lines determined by barycentric centroids. Numerical experiments performed have confirmed a good performance of proposed method.

 

Fuzzy Modeling with Genetic Algorithms

V. Wuwongse, S. Veluppilai

Abstract. Recent applications of fuzzy control have created an urgent demand for fuzzy modelling techniques. Several methods for identification of fuzzy models from numerical input-output samples have been proposed. Among them, Sugeno and Yasukawa's method [6], which employs fuzzy c/means clustering, holds significant promises. This paper improves the method of Sugeno and Yasukawa. Identified fuzzy models are tuned at various stages by means of genetic algorithms, i.e., the numbers of input variables and rules are reduced and membership function parameters are adjusted. The technique, when applied to a nonlinear system, demonstrates its efficiency in a comparison with the original method of Sugeno and Yasukawa.

 

On the Average Number of Solutions for SAT Instances

H. Drias, A. Bensalma

Abstract. In this paper, we are interested in counting solutions for instances of satisfiability and more precisely we try to extend the formula for the average number of solutions of random instances proposed in [4] to a large class of instances. In fact the formula given in this reference works for the specific class of instances where all clauses are dependent. When we consider the independence characteristic of clauses, we find a more general mathematical expression. The computation of the average number of solutions with the actual formula depends only on the structure of independence of the instance. The latter is defined to be the set of subsets of independent clauses.

Searching the structure of independence for an instance is shown to be NP-hard. An algorithm in time O (nk2)  is designed for finding an approximate structure of an instance, k being the number of clauses and n the number of variables of the instance. Even though an approximate structure of independence is considered in the calculation of the average number of solutions, our formula yields results with more accuracy.

 

Lifting of L-Narrowing Derivations

P. Bachmann

Abstract. If conditional rewrite/rules are restricted to the form  PÞ f (x1, …, xn) ® t where P is a finite set of equations, f is any function symbol, x1, …, xn are variables, and t is any term when the premise P contains in general variables which do not occur in the list x1, …, xn. The rule with premise P can be applied if P is satisfiable. Therefore, we need methods to solve P and narrowing must be combined with rewriting. But, narrowing becomes a special case, called L-narrowing, closely related to lay-narrowing. Two lifting lemmas are shown which characterize the relationship of L/narrowing derivations if the goals are modified by substitutions. From these lifting lemmas, soundness and completeness results can be concluded.


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