Abstract The aim of this paper is to investigate the behaviour projective images groups which are finite over a term their upper central series. In particular, we prove that for any positive integer k , class finitely generated in -th series has index can be described terms lattice invariants, and so it invariant under projectivities. context, also study have only many maximal subgroups not per...

in this paper we classify fuzzy subgroups of the dihedral group $d_{pqrs}$  for distinct primes  $p$, $q$, $r$ and $s$. this follows similar work we have done on distinct fuzzy subgroups of some dihedral groups.we present formulae for the number of (i) distinct maximal chains of subgroups, (ii) distinct fuzzy subgroups and (iii) non-isomorphic classes of fuzzy subgroups under our chosen equival...

Target space symmetries are studied for orbifold compactified string theories containing Wilson line background fields. The symmetries determined are for those moduli which contribute to the string loop threshold corrections of the gauge coupling constants. The groups found are subgroups of the modular group P SL(2, Z) and depend on the choice of discrete Wilson lines and the shape of the under...

Given a group G acting on a set S, Mobius inversion over the lattice of subgroups can be used to obtain congruences relating the number of elements of S stabilized by each subgroup. By taking S to be a set of subsets, partitions, or permutations congruences for binomial and multinomial coefficients. Stirling numbers of both kinds, and various other combinatorial sequences are derived. Congruenc...

Let G be a finite product of SL(2,Ki)′s for local fields Ki of characteristic zero. We present a discreteness criterion for non-solvable subgroups of G containing an irreducible lattice of a maximal unipotent subgroup of G. In particular such a subgroup has to be arithmetic. This extends a previous result of A. Selberg when G is a product of SL2(R)′s.

In this paper‎, ‎we give a complete proof of Theorem 4.1(ii) and a new‎ ‎elementary proof of Theorem 4.1(i) in [Li and Shen‎, ‎On the‎ ‎intersection of the normalizers of the derived subgroups of all‎ ‎subgroups of a finite group‎, ‎ J‎. ‎Algebra, ‎323  (2010) 1349--1357]‎. ‎In addition‎, ‎we also give a generalization of Baer's Theorem‎.

We propose a mathematical formulation of the algorithm of Hanany and Vegh [22] to associate quivers with relations to lattice polygons. We study the case of toric del Pezzo surfaces in detail and discuss its relation with coamoebas following Feng, He, Kennaway and Vafa [10]. As an application, we prove homological mirror symmetry for orbifolds of toric del Pezzo surfaces by finite subgroups of ...

In this paper, the buckling behavior of a composite lattice cylindrical shell is studied and effects of rib defects on the distribution of stress field and buckling response of the shell is investigated. A three dimensional finite element buckling analysis of the lattice shell is carried out using ANSYS suit of program. Geometrical data and material properties of the shell are obtained from the...