BULLETIN OF THE IRANIAN MATHEMATICAL SOCIETY
Year:2005 | Volume:31 | Issue:2|Papers Count:7

This paper is concerned with the reducing sequences introduced by Auslander-Buchsbaum [1]. A bound from above for the Krull dimension of the Koszul homology modules with respect to a reducing sequence is shown. Using reducing sequence, a result on the Artinianness and the finiteness of the support of the local cohomology modules is given.

In [30] a class of quasi-cyclic LDPC codes has been proposed, whose information rate is 1/2. We generalize that construction to arbitrary rates l-1/l and we provide a Grobner basis for their dual codes, in some generic cases.

Given a finite group G, let p(G) denote the probability that a randomly chosen element in G has a square root. The object of this paper is to show that the set {p(G) |G is a finite group} is a dense subset of the closed interval [0,1].

This paper is dealing with the application of the notion of semi-q-open sets in topological spaces in order to present and study new classes of maps called contra pre-semi-q-open maps and contra pre-semi-B-closed maps. In this connection, two classes of maps called semi- qc-homeomorphism and contra semi- qc homeomorphism are introduced. It turns out that the union of the families of all semi-qc-homeomorphisms and contra semi- qc-homeomorphisms forms a group under the composition of maps.

We derive a formula for the maximum number of edges in a strongly multiplicative graph as a function of its order.

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