共查询到20条相似文献,搜索用时 46 毫秒
1.
Let be a continuous map and a constant map between closed orientable surfaces of genus h,g, respectively. By definition the pair (f,c) has the Wecken property if f can be deformed into a map such that every coincidence classes of (f',c) is essential and consists of exactly one point. The main result is that (f,c) has the Wecken property if and only if where . Certain quadratic equations in free groups closely related to the coincidence problem are solved.
Received January 26, 1999; in final form December 10, 1999 / Published online March 12, 2001 相似文献
2.
Robert F. Brown Christina L. Soderlund 《Journal of Fixed Point Theory and Applications》2007,2(1):41-53
Let
be a fiber bundle where E, B and Y are connected finite polyhedra. Let
be a fiber-preserving map and
a closed, locally contractible subset. We present necessary and sufficient conditions for A and its subsets to be the fixed point sets of maps fiber homotopic to f. The necessary conditions correspond to those introduced by Schirmer in 1990 but, in the fiber-preserving setting, homotopies
are fiberpreserving. Those conditions are shown to be sufficient in the presence of additional hypotheses on the bundle and
on the map f. The hypotheses can be weakened in the case that f is fiber homotopic to the identity. 相似文献
3.
Daciberg L. Gonçalves Elena Kudryavtseva Heiner Zieschang 《manuscripta mathematica》2002,107(3):311-341
Let f:M
1→M
2 be a continuous map and c:M
1→M
2 a constant map between closed (not necessarily orientable) surfaces. By definition the pair (f,c) has the Wecken property if f can be deformed into a map f' such that the number of coincidence points of (f',c) is the same as the number of essential coincidence classes of (f,c) and, hence, every essential coincidence class consists of exactly one point. When both surfaces are orientable the problem
to determine all maps which have the Wecken property was solved in [14]. Let A(f) denote the absolute degree as defined in [6] or [15] and . Here we show that a map f has the Wecken property iff either the Euler characteristic or . In free groups there are solved certain quadratic equations closely related to the root problem.
Received: Received: 18 January 2001 / Revised version: 27 November 2001 相似文献
4.
Let M be an n-dimensional complete non-compact submanifold in a hyperbolic space with the norm of its mean curvature vector bounded by
a constant . We prove in this paper that . In particular when M is minimal we have and this is sharp because equality holds when M is totally geodesic.
Received September 14, 1999; in final form November 12, 1999 / Published online December 8, 2000 相似文献
5.
Yongdo Lim 《Mathematische Annalen》2000,316(2):379-389
Let V be a simple Euclidean Jordan algebra with an associative inner product and let be the corresponding symmetric cone. Let be the compact symmetric space of all primitive idempotents of V. We show that the function s(a,b) defined by
is a (the automorphism group of )-invariant complete metric on and it coincides with a natural Finsler distance on We also show that the metric s(a,b) (strictly) contracts any (strict) conformal compression of .
Received: 24 May 1999 / in final form: 15 March 1999 相似文献
6.
7.
Let (G, H) be an irreducible semisimple symmetric pair,P
G a parabolic subgroup. Suppose that theL-orbit of the base point in the flag manifoldG/P is open and writeS(L,P)={gG:gL
LP} for the compression semigroup of this orbit. We show that ifP is minimal andS(L, P)=G, then (G, H) is Riemannian and we give a geometric characterization of those cases whereS(L, P) has non-empty interior different fromG. IfG/H is a symmetric space of regular type, then we show under certain additional assumptions thatS(L, Q) is an Ol'shanskiî semigroup.Supported by a DFG Heisenberg-grant. 相似文献
8.
Richard Pink 《manuscripta mathematica》2000,102(1):1-24
Let X be an irreducible smooth projective curve over an algebraically closed field of characteristic p>0. Let ? be either a finite field of characteristic p or a local field of residue characteristic p. Let F be a constructible étale sheaf of $\BF$-vector spaces on X. Suppose that there exists a finite Galois covering π:Y→X such that the generic monodromy of π*
F is pro-p and Y is ordinary. Under these assumptions we derive an explicit formula for the Euler–Poincaré characteristic χ(X,F) in terms of easy local and global numerical invariants, much like the formula of Grothendieck–Ogg–Shafarevich in the case
of different characteristic. Although the ordinariness assumption imposes severe restrictions on the local ramification of
the covering π, it is satisfied in interesting cases such as Drinfeld
modular curves.
Received: 7 December 1999 / Revised version: 28 January 2000 相似文献
9.
Let P be a simple lattice polytope. We define an action of the Hecke operators on E(P), the Ehrhart polynomial of P, and describe their effect on the coefficients of E(P). We also describe how the Brion–Vergne formula for E(P) transforms under the Hecke operators for nonsingular lattice polytopes P.
相似文献
10.
Let M be an irreducible, orientable, closed 3-manifold with fundamental group G. We show that if the pro-p completion
of G is infinite then G is either soluble-by-finite or contains a free subgroup of rank 2.
Both authors are partially supported by “Bolsa de produtividade de pesquisa” from CNPq, Brazil.
Received: 16 February 2006 相似文献
11.
Jiang Ming CHANG Ming Liang FANG 《数学学报(英文版)》2007,23(6):973-982
Let f be a nonconstant entire function; let k ≥ 2 be a positive integer; and let a be a nonzero complex number. If f(z) = a→f′(z) = a, and f′(z) = a →f^(k)(z) = a, then either f = Ce^λz + a or f = Ce^λz + a(λ - 1)/)λ, where C and ), are nonzero constants with λ^k-1 = 1. The proof is based on the Wiman-Vlairon theory and the theory of normal families in an essential way. 相似文献
12.
Let X be a projective manifold, a locally free ample subsheaf of the tangent bundle T
X
. If and or n, we prove that . Furthermore we investigate ampleness properties of T
X
on large families of curves and the relation to rational connectedness.
Received: 2 July 1996 相似文献
13.
14.
Let G be a noncompact semi-simple Lie group and a Lie semigroup with nonempty interior. We study the homotopy groups , , of S. Generalizing a well known fact for G, it is proved that there exists a compact and connected subgroup such that is isomorphic to . Furthermore, there exists a coset
z contained in int S which is a deformation retract of S.
Received 6 December 2000; in revised form 23 November 2001 相似文献
15.
Let A, B be associative rings with identity, and (S, ≤) a strictly totally ordered commutative monoid which is also artinian. For any bimodule AMB , we construct a bimodule A[[S]]M[S]B[[S]] and prove that AMB defines a quasi-duality if and only if the bimodule A[[S]]M[S]B[[S]] defines a quasi-duality. As a corollary, it is shown that if a ring A has a quasi-duality then the ring A[[S]] of generalized power series over A has a quasi-duality. 相似文献
16.
Mario Petrich 《Monatshefte für Mathematik》2000,129(4):329-340
A subsemigroup S of a semigroup Q is an order in Q if for every there exist such that , where a and d are contained in (maximal) subgroups of Q, and and are their inverses in these subgroups. A regular semigroup S is strict if it is a subdirect product of completely (0-)simple semigroups.
We construct all orders and involutions in Auinger’s model of a strict regular semigroup. This is used to find necessary and
sufficient conditions on an involution on an order S in a strict regular semigroup Q for extendibility to an involution on Q.
(Received 27 April 1999; in revised form 20 October 1999) 相似文献
17.
Harmonic morphisms as unit normal bundles¶of minimal surfaces 总被引:2,自引:0,他引:2
Let be an isometric immersion between Riemannian manifolds and be the unit normal bundle of f. We discuss two natural Riemannian metrics on the total space and necessary and sufficient conditions on f for the projection map to be a harmonic morphism. We show that the projection map of the unit normal bundle of a minimal surface in a Riemannian
manifold is a harmonic morphism with totally geodesic fibres.
Received: 6 February 1999 相似文献
18.
We formulate a general condition, called an enlargement, under which a semigroup T is covered by a Rees matrix semigroup over a subsemigroup.
(Received 1 February 1999; in revised form 19 May 1999) 相似文献
19.
Let X be a Stein manifold. Then we prove that for any family ℱ⊂?(X) the normality domain Dℱ) is a meromorphically ?(X)-convex open set of X.
Received: 4 November 1999 相似文献
20.
Let S be a multiplicative semigroup of matrices with nonnegative entries. Assume that the diagonal entries of the members of S form a finite set. This paper is concerned with the following question: Under what circumstances can we deduce that S itself is finite? 相似文献