let $gamma(s_n)$ be the minimum number of proper subgroups‎ ‎$h_i, i=1‎, ‎dots‎, ‎l $ of the symmetric group $s_n$ such that each element in $s_n$‎ ‎lies in some conjugate of one of the $h_i.$ in this paper we‎ ‎conjecture that $$gamma(s_n)=frac{n}{2}left(1-frac{1}{p_1}right)‎ ‎left(1-frac{1}{p_2}right)+2,$$ where $p_1,p_2$ are the two smallest primes‎ ‎in the factorization of $ninmathbb{n}$ an...

Stainless steel square honeycomb core sandwich and solid monolithic beams have been subjected to high-pressure, short-duration impulses using a shock simulation technique involving high-speed impact of Al foam projectiles. The experiments have been designed to achieve two objectives: (i) to demonstrate the benefits of sandwich construction, and (ii) to assess the fidelity of dynamic finite elem...

Let S be a multiplicatively idempotent congruence-simple semiring. We show that $$|S|=2$$ if has absorbing element. also prove is finite then either or $$S\cong {{\,\textrm{End}\,}}(L)$$ $$S^{op}\cong where L the 2-element semilattice. It seems to an open question, whether can infinite at all.

This paper is concerned with the development of an efficient and accurate finite element procedure for the solution directly in the time domain of transient problems involving structures submerged in an infinite acoustic fluid. The central feature of the procedure is a novel impedance, or, absorbing boundary, element that is used to render the computational domain finite. This element is local ...

ABSTRACT: Shear wall is commonly employed as a principal element to resist lateral loads due to wind or earthquake forces. An accurate model for a shear wall system needs to consider the effect of all components for analyses i.e. shear wall, foundation, and subsoil. This investigation presents the modeling of a shear wall structure foundation and soil system using the super element, finite and ...

We study a generalization of the Canonical Element Conjecture. In particular we show that given a nonregular local ring (A, m) and an i > 0, there exist finitely generated A-modules M such that the canonical map from ExtA(M/mM,Syzi(M/mM)) to Hi m (M,Syzi(M/mM)) is nonzero. Moreover, we show that even when M has infinite projective dimension and i > dim(A), studying these maps sheds light on the...

a group g is said to be a (pf)c-group or to have polycyclic-by-finite conjugacy classes, if g/c_{g}(x^{g}) is a polycyclic-by-finite group for all xin g. this is a generalization of the familiar property of being an fc-group. de falco et al. (respectively, de giovanni and trombetti) studied groups whose proper subgroups of infinite rank have finite (respectively, polycyclic) conjugacy classes. ...

A greedy heuristic to solve a given combinatorial optimisation problem can be seen as an element of an infinite set of heuristics, H, which is defined by a function that depends on several parameters. We propose a procedure for determining the best element of H for a set of instances of the combinatorial optimisation problem. The procedure consists essentially in applying a direct non-linear op...