共查询到20条相似文献,搜索用时 15 毫秒
1.
Daniel T. Wise 《Inventiones Mathematicae》2002,149(3):579-617
A subgroup M⊂G is almost malnormal provided that for each g∈G−M, the intersection M
g
∩M is finite. It is proven that the free product of two virtually free groups amalgamating a finitely generated almost malnormal
subgroup, is residually finite. A consequence of a generalization of this result is that an acute-angled n-gon of finite groups is residually finite if n≥4. Another consequence is that if G acts properly discontinuously and cocompactly on a 2-dimensional hyperbolic building whose chambers have acute angles and
at least 4 sides, then G is residually finite.
Oblatum 17-VII-2000 & 13-II-2002?Published online: 29 April 2002 相似文献
2.
Erik Elfving 《manuscripta mathematica》2001,105(2):235-251
In this paper we study proper locally linear actions of Lie groups on topological manifolds and prove that such G-spaces have the G-homotopy type of a G-CW complex. Results on G-invariant metrics and equivariant embeddings into Banach G-spaces are also obtained.
Received: 19 June 2000 相似文献
3.
We provide involutory symmetric generating sets of finitely generated Coxeter groups, fulfilling a suitable finiteness condition,
which in particular is fulfilled in the finite, affine and compact hyperbolic cases.
相似文献
4.
Kevin Houston 《Inventiones Mathematicae》2002,147(3):471-485
The disentanglement of certain augmentations is shown to be the topological join of a disentanglement and a Milnor fibre.
The kth disentanglement of a finite map is defined and for corank 1 maps from ℂ
n
to ℂ
n
+1 it is shown that they are homotopically equivalent to a wedge of spheres. Applications to the Mond conjecture are given.
Oblatum 24-VII-2000 & 5-VII-2001?Published online: 12 October 2001 相似文献
5.
6.
In [6], ?evik defined necessary and sufficient conditions for the presentation of a central extension of a cyclic group by
an ordinary group to be p-Cockcroft, where p is a prime or 0. In this paper, as a next step of this above result, we will define the p-Cockcroft property for the presentation of a central extension of an abelian group by any group. Finally, as an application
of the main result, we will present an example. 相似文献
7.
Allen Knutson 《Advances in Mathematics》2004,184(1):161-176
Let (Π,Σ) be a Coxeter system. An ordered list of elements in Σ and an element in Π determine a subword complex, as introduced in Knutson and Miller (Ann. of Math. (2) (2003), to appear). Subword complexes are demonstrated here to be homeomorphic to balls or spheres, and their Hilbert series are shown to reflect combinatorial properties of reduced expressions in Coxeter groups. Two formulae for double Grothendieck polynomials, one of which appeared in Fomin and Kirillov (Proceedings of the Sixth Conference in Formal Power Series and Algebraic Combinatorics, DIMACS, 1994, pp. 183-190), are recovered in the context of simplicial topology for subword complexes. Some open questions related to subword complexes are presented. 相似文献
8.
Phugraveng Hö Hài 《代数通讯》2013,41(3):1085-1117
A presentation for an arbitrary group extension is well known. A generalization of the work by Conway et al. (Group Tensor1972, 25, 405–418) on central extensions has been given by Baik et al. (J. Group Theor.). As an application of this we discuss necessary and sufficient conditions for the presentation of the central extension to be p-Cockcroft, where p is a prime or 0. Finally, we present some examples of this result. 相似文献
9.
If Δ is a polytope in real affine space, each edge of Δ determines a reflection in the perpendicular bisector of the edge.
The exchange groupW (Δ) is the group generated by these reflections, and Δ is a (Coxeter) matroid polytope if this group is finite. This simple
concept of matroid polytope turns out to be an equivalent way to define Coxeter matroids. The Gelfand-Serganova Theorem and
the structure of the exchange group both give us information about the matroid polytope. We then specialize this information
to the case of ordinary matroids; the matroid polytope by our definition in this case turns out to be a facet of the classical
matroid polytope familiar to matroid theorists.
This work was supported in part by NSA grant MDA904-95-1-1056. 相似文献
10.
In the recent paper [Adv. Applied Math., 38 (2007), 210–226] it is proved that the special matchings of permutations generate
a Coxeter group. In this paper we generalize this result to a class of Coxeter groups which includes many Weyl and affine
Weyl groups. Our proofs are simpler, and shorter, than those in [loc. cit.]
All authors are partially supported by EU grant HPRN-CT-2001-00272.
Received: 30 October 2006 相似文献
11.
Karl-Hermann Neeb 《Monatshefte für Mathematik》2000,131(2):123-153
In this paper we give a characterization of those reductive or solvable connected, not necessarily simply connected, Lie
groups which permit a non-degenerate group order. A non-degenerate group ordering on G always defines a pointed generating invariant convex cone W in the Lie algebra of G, but not every such cone arises in this way. The cones that do are called global. To decide whether a given cone is global
or not is a difficult problem which for simply connected groups and invariant cones has completely been solved by Gichev.
(Received 22 October 1999; in revised form 3 March 2000) 相似文献
12.
13.
Thierry Coulbois 《Archive for Mathematical Logic》2001,40(7):523-524
F. Oger proved that if A is a finite group, then the class of groups which are abelian-by-A can be axiomatized by a single first order sentence. It is established here that, in Oger's result, the word abelian cannot
be replaced by group.
Received: 15 March 1996 / Published online: 18 July 2001 相似文献
14.
We prove that any topological loop homeomorphic to a sphere or to a real projective space and having a compact-free Lie group
as the inner mapping group is homeomorphic to the circle. Moreover, we classify the differentiable 1-dimensional compact loops
explicitly using the theory of Fourier series.
Authors’ addresses: ágota Figula, Mathematisches Institut der Universit?t Erlangen-Nürnberg, Bismarckstr. 1 1/2, 91054 Erlangen,
Germany and Institute of Mathematics, University of Debrecen, P.O.B. 12, H-4010 Debrecen, Hungary; Karl Strambach, Mathematisches
Institut der Universit?t Erlangen-Nürnberg, Bismarckstr. 1 1/2, 91054 Erlangen, Germany 相似文献
15.
16.
Igor Mineyev 《Mathematische Zeitschrift》2000,233(2):327-345
We introduce the notion of an -combing and use it to show that hyperbolic groups satisfy linear isoperimetric inequalities for filling real cycles in each positive dimension. S. Gersten suggested the concept of metabolicity (over or ) for groups which implies hyperbolicity. Metabolicity admits several equivalent definitions: by vanishing of -cohomology, using combings, and others. We prove several criteria for a group to be hyperbolic, -metabolicity being among them. In particular, a finitely presented group G is hyperbolic iff for any normed vector space V and any .
Received December 9, 1998 相似文献
17.
Coxeter matroids, introduced by Gelfand and Serganova, are combinatorial structures associated with any finite Coxeter group
and its parabolic subgroup they include ordinary matroids as a specia case. A basic result in the subject is a geometric characterization
of Coxeter matroids first stated by Gelfand and Serganova. This paper presents a self-contained, simple proof of a more general
version of this geometric characterization. 相似文献
18.
Wilfried Buchholz 《Archive for Mathematical Logic》2001,40(4):255-272
Using the concept of notations for infinitary derivations we give an explanation of Takeuti's reduction steps on finite derivations (used in his consistency proof for Π1
1-CA) in terms of the more perspicious infinitary approach from [BS88].
Received: 27 April 1999 / Published online: 21 March 2001 相似文献
19.
Luca Moci 《Journal of Pure and Applied Algebra》2011,215(8):1980-1989
20.
Hee Oh 《Mathematische Annalen》2001,321(4):789-815
We generalize Margulis's S-arithmeticity theorem to the case when S can be taken as an infinite set of primes. Let R be the set of all primes including infinite one and set . Let S be any subset of R. For each , let be a connected semisimple adjoint -group and be a compact open subgroup for each finite prime . Let denote the restricted topological product of 's, with respect to 's. Note that if S is finite, . We show that if , any irreducible lattice in is a rational lattice. We also present a criterion on the collections and for to admit an irreducible lattice. In addition, we describe discrete subgroups of generated by lattices in a pair of opposite horospherical subgroups.
Received: 30 November 2000 / Revised version: 2 April 2001 / Published online: 24 September 2001 相似文献