Association schemes are combinatorial objects that allow us solve problems in several branches of mathematics. They have been used in the study of permutation groups and graphs and also in the design of experiments, coding theory, partition designs etc. In this paper we show some techniques for computing properties of association schemes. The main framework arises from the fact that we can char...

We present a new approach to the construction of simple block designs. Using the computer package DISCRETA, we start with the construction of block designs which are invariant with respect to some prescribed group of automorphisms. Therefore, one applies the method of Kramer and Mesner which means that one has to solve systems of diophantine equations to get the designs. DISCRETA has proven its...

Several intersection matrices of s-subsets versus k-subsets of a v-set are introduced in the literature. We study these matrices systematically through counting arguments and generating function techniques. A number of new or known identities appear as natural consequences of this viewpoint; especially, use of the derivative operator d/dz and some related operators reveals some connections betw...

the matrix functions appear in several applications in engineering and sciences. the computation of these functions almost involved complicated theory. thus, improving the concept theoretically seems unavoidable to obtain some new relations and algorithms for evaluating these functions. the aim of this paper is proposing some new reciprocal for the function of block anti diagonal matrices. more...

Geneva, Switzerland: World Health Organization; 2007. 6. Splettstoesser WD, Tomaso H, Al Dahouk S, Neubauer H, SchuffWerner P. Diagnostic procedures in tularaemia with special focus on molecular and immunological techniques. J Vet Med B Infect Dis Vet Public Health 2005;52:249–261. 7. Jones RM, Nicas M, Hubbard A, Sylvester MD, Reingold A. The infectious dose of Francisella tularensis (tularemi...