Search results for "covering"
showing 10 items of 61 documents
A Group-theoretical Finiteness Theorem
2008
We start with the universal covering space $${\*M^n}$$ of a closed n-manifold and with a tree of fundamental domains which zips it $${T\longrightarrow\*M^n}$$ . Our result is that, between T and $${\* M^n}$$ , is an intermediary object, $${T\stackrel{p} {\longrightarrow} G \stackrel{F}{\longrightarrow} \*M^n}$$ , obtained by zipping, such that each fiber of p is finite and $${T\stackrel{p}{\longrightarrow}G\stackrel{F}{\longrightarrow} \*M^n}$$ admits a section.
A note on coverings with special fibres and monodromy group $ S_{d}$
2012
We consider branched coverings of degree over with monodromy group , points of simple branching, special points and fixed branching data at the special points, where is a smooth connected complex projective curve of genus , and , are integers with . We prove that the corresponding Hurwitz spaces are irreducible if .
Central idempotents and units in rational group algebras of alternating groups
1998
Let ℚAn be the group algebra of the alternating group over the rationals. By exploiting the theory of Young tableaux, we give an explicit description of the minimal central idempotents of ℚAn. As an application we construct finitely many generators for a subgroup of finite index in the centre of the group of units of ℚAn.
Equidistribution of Common Perpendicular Arcs
2019
In this chapter, we prove the equidistribution of the initial and terminal vectors of common perpendiculars of convex subsets, at the universal covering space level, for Riemannian manifolds and for metric and simplicial trees.
On permutations of class sums of alternating groups
1997
We prove a result concerning the class sums of the alternating group An; as a consequence we deduce that if θ is a normalized automorphism of the integral group ring then there exists such that is the identity on , where Sn:is the symmetric group and is the center of
A Case-Study of Green Roof Monitoring: The Building of Council for Agricultural Research and Economics in Bagheria, (Italy)
2018
The energy saving in building goes on as an important challenge in the policy of Developed Countries. While the issue of energy building efficiency in heating season has deeply been investigated for a long time, the issue of energy building efficiency in cooling season is relatively recent. Moreover, considering the increase of electric consumption for air-conditioning in summer, mainly due to the growing quality of life, the research of technologies for reducing energy building consumption during this season becomes essential. The green roof represents a technology useful to reduce the energy consumption during the cooling season. In this work the authors report the results of a monitoring…
A more efficient method for clustering sheet metal shapes
2007
The nesting of two-dimensional irregular shapes is a common problem which is frequently encountered by a number of industries where raw material has to be, as economically as possible, cut from a given stock sheet. A frequently recurring problem as far as cutting stock is concerned, is how to obtain the best nesting of some pieces of flat patterns which occupy minimalarea convex enclosure. The area of convex enclosure is related to the convex hull of the union of patterns which can be imagined as a large rubber band surrounding the set of all polygons. Our goal is to automatically obtain the smallest area convex shape containing all the patterns. As a matter of fact, Cheng and Rao have prop…
An Optimized Roadside Units (RSU) Placement for Delay-Sensitive Applications in Vehicular Networks
2015
International audience; Over the last few years, a lot of applications have been developed for Vehicular Ad Hoc NETworks (VANETs) to exchange information between vehicles. However, VANET is basically a Delay Tolerant Network (DTN) characterized by intermittent connectivity, long delays and message losses especially in low density regions [1]. Thus, VANET requires the use of an infrastructure such as Roadside Units (RSUs) that permits to enhance the network connectivity. Nevertheless, due to their deployment cost, RSUs need to be optimally deployed. Hence, the main objective of this work is to provide an optimized RSUs placement for delay-sensitive applications in vehicular networks that imp…
Architectures “on ruins” and ambiguous transparency: the glass in preservation and communication of archaeology
2008
Abstract The contemporary architecture is characterized by an even more marked transparency, as a result of a continuous experimentation all directed towards the search of the built “lightness”, that is towards the “dematerialization” of the architecture and the consequent loss of weight connected to the excess of form. It is in 1851 that a New Architectural Age springs because of the realization of the Crystal Palace, in London – that has addressed towards the experimentation of the glass as an architectural, structural element and of design. Today, part of this experimentation has been applied for some interventions of coverage, protection and communication in situ of the archaeological r…
Some results concerning simple locally finite groups of 1-type
2005
AbstractIn this paper several aspects of infinite simple locally finite groups of 1-type are considered. In the first part, the classes of diagonal limits of finite alternating groups, of diagonal limits of finite direct products of alternating groups, and of absolutely simple groups of 1-type are distinguished from each other. In the second part, inductive systems of representations over fields of characteristic zero (which are known to correspond to ideals in the group algebra) are studied in general for groups of 1-type. The roles of primitive respectively imprimitive representations in inductive systems are investigated. Moreover it is shown that in any proper inductive system the depth…