共查询到20条相似文献,搜索用时 15 毫秒
1.
Miklós Dormán 《Algebra Universalis》2008,58(4):479-492
In this paper we determine all collapsing transformation monoids that contain at least one unary constant operation and whose
nonconstant operations are permutations. Furthermore, we find an infinite family of transformation monoids that consist of
at least three unary constant operations and some permutations for which the corresponding monoidal intervals are 2-element
chains.
This research is supported by Hungarian National Foundation for Scientific Research grant nos. T 37877 and K 60148. 相似文献
2.
H. Karzel S. Pianta 《Abhandlungen aus dem Mathematischen Seminar der Universit?t Hamburg》2005,75(1):203-214
We describe a representation of any semiregularleft loop by means of asemiregular bipartite involution set or, equivalently, a 1-factorization (i.e., a parallelism) of a bipartite graph, with at least one transitive vertex.
In these correspondences,Bol loops are associated on one hand toinvariant regular bipartite involution sets and, on the other hand, totrapezium complete bipartite graphs with parallelism; K-loops (or Bruck loops) are further characterized by a sort of local Pascal configuration in the related graph.
Research partially supported by the Research Project of M.I.U.R. (Italian Ministry of Education, University and Research)
“Strutture geometriche, combinatoria e loro applicazioni” and by the Research group G.N.S.A.G.A. of INDAM. 相似文献
3.
Bokhee Im Helmut Karzel Hayi-Joo Ko 《Abhandlungen aus dem Mathematischen Seminar der Universit?t Hamburg》2002,72(1):9-20
In a web one can define in a natural way reflections in generators and a kind of rotations in points. The structure of the webs and the corresponding loops in which some of these maps are automorphisms will be studied in a synthetic way. 相似文献
4.
A fundamental result concerning collapsed manifolds with bounded sectional curvature is the existence of compatible local
nilpotent symmetry structures whose orbits capture all collapsed directions of the local geometry [CFG]. The underlying topological
structure is called an N-structure of positive rank. We show that if a manifold M admits such an N-structure , then M admits a one-parameter family of metrics g
∈ with curvature bounded in absolute value while injectivity radii and the diameters of -orbits away from the singular set of uniformly converge to zero as . Moreover, g
∈ is -invariant away from the singular set. This result extends collapsing results in [CG1], [Fu3] and [G].
Q.C. supported partially by a Jingshi research fund from Beijing Normal University. X.R. supported partially by NSF Grant
DMS 0504534 and by a Jingshi research fund from Beijing Normal University. 相似文献
5.
J. Kellendonk and M. V. Lawson established that each partial action of a group G on a set Y can be extended to a global action of G on a set Y
G
containing a copy of Y. In this paper we classify transitive partial group actions. When G is a topological group acting on a topological space Y partially and transitively we give a condition for having a Hausdorff topology on Y
G
such that the global group action of G on Y
G
is continuous and the injection Y into Y
G
is an open dense equivariant embedding.
相似文献
6.
A. V. Kartashova 《Russian Mathematics (Iz VUZ)》2009,53(4):20-25
We consider the variety of unary algebras 〈A, f, g〉 defined by the identities f(g(x)) = g(f(x)) = x. We describe algebras of this variety, whose topology lattices are modular, distributive, linearly ordered, complemented, or pseudocomplemented. 相似文献
7.
Mark V. Lawson 《Periodica Mathematica Hungarica》2009,58(2):189-207
We characterise the maximal proper closed inverse submonoids of the polycyclic inverse monoids, also known as Cuntz inverse
semigroups, and so determine all their primitive partial permutation representations. We relate our results to the work of
Kawamura on certain kinds of representations of the Cuntz C*-algebras and to the branching function systems of Bratteli and Jorgensen.
相似文献
9.
We study the operad of finite labeled tournaments. We describe the structure of suboperads of this operad generated by simple tournaments. We prove that a suboperad generated by a tournament with two vertices (i.e., the operad of finite linearly ordered sets) is isomorphic to the operad of symmetric groups, and a suboperad generated by a simple tournament with more that two vertices is isomorphic to the quotient operad of the free operad with respect to a certain congruence. We obtain this congruence explicitly. 相似文献
10.
I. Kocsis 《Acta Mathematica Hungarica》2008,118(4):307-312
Let X ⊂ ℝ be an interval of positive length and define the set Δ = {(x, y) ∈ X × X | x ≧ y}. We give the solution of the equation
which holds for all (x, y) ∈ Δ and (u, υ) ∈ Δ, where the functions F: X → X, G
1: Δ → X, G
2: Δ → X, and G: F(X, X) × F(X, X) → X are continuous and strictly monotonic in each variable.
This research was supported by the Hungarian Scientific Research Fund (OTKA), grant No. T-043080. 相似文献
11.
Some remarks on trigonometric sums 总被引:1,自引:1,他引:0
Let
where m
1 < m
2 < … < m
t
≦ , δ
x
→ 0, p runs over the primes p ≧ ≦ 1, |X
p
| ≦ 1. It is assumed that m
v
, , X
p
may depend on x.
Assume that . It is proved that
for almost all irrational α, π(x) = number of primes up to x.
Research supported by the Applied Number Theory Research Group of the Hungarian Academy of Science and by a grant from OTKA
T46993. 相似文献
12.
E. A. Utkina 《Russian Mathematics (Iz VUZ)》2009,53(4):40-44
We consider a problem with shifts in boundary conditions for the Bianchi equation in a four-dimensional space. We establish sufficient conditions which allow one to evaluate its unique solution in terms of the Riemann function. 相似文献
13.
Nicholas M. Katz 《Geometric And Functional Analysis》2008,18(4):1251-1269
We give sharp estimates for certain families of exponential sums in several variables over finite fields.
Received: May 2007, Accepted: September 2007 相似文献
14.
J. L. García-Roig Emma Martín-Gutiérrez 《Abhandlungen aus dem Mathematischen Seminar der Universit?t Hamburg》2000,70(1):85-92
We solve the functional equationf(x
3 +y
3) =f(x)3 +f(y)3 for maps of a finite field into itself. 相似文献
15.
Vladimir Turaev 《Japanese Journal of Mathematics》2007,2(1):1-39
We discuss a topological approach to words introduced by the author in [Tu2]–[Tu4]. Words on an arbitrary alphabet are approximated
by Gauss words and then studied up to natural modifications inspired by the Reidemeister moves on knot diagrams. This leads
us to a notion of homotopy for words. We introduce several homotopy invariants of words and give a homotopy classification
of words of length five.
Based on notes by Eri Hatakenaka, Daniel Moskovich, and Tadayuki Watanabe 相似文献
16.
A. Joós 《Acta Mathematica Hungarica》2008,119(4):307-321
We construct a convex body K ⊃ ℝ3 such that the maximum number of mutually nonoverlapping translates of K which touch K is 15.
The work is in part supported by grant no. T043556 of the Hungarian National Science Foundation (OTKA). 相似文献
17.
For k an algebraic closure of the finite field , ℓ prime distinct from p and X a surface over k, we prove that the field of rational functions k(X) can be recovered from the maximal pro-ℓ-quotient of its absolute Galois group – in fact already from the second central descending series quotient of .
Submitted: July 2004, Revision: October 2005, Final revision: February 2008, Accepted: February 2008 相似文献
18.
Christian Pries 《Geometric And Functional Analysis》2009,18(5):1774-1785
Given a C
∞ Riemannian metric g on
P
2 we prove that (, g) has constant curvature iff all geodesics are closed. Therefore is the first non-trivial example of a manifold such that the smooth Riemannian metrics which involve that all geodesics are
closed are unique up to isometries and scaling. This remarkable phenomenon is not true on the 2-sphere, since there is a large
set of C
∞ metrics whose geodesics are all closed and have the same period 2π (called Zoll metrics), but no metric of this set can be
obtained from another metric of this set via an isometry and scaling. As a corollary we conclude that all two-dimensional
P-manifolds are SC-manifolds.
Received: April 2007; Revision: September 2007; Accepted: September 2007 相似文献
19.
Tudor Zamfirescu 《Periodica Mathematica Hungarica》2008,57(2):227-230
Suppose a convex body wants to pass through a circular hole in a wall. Does its ability to do so depend on the thickness of the wall? In fact in most cases it does, and in this paper we present a sufficient criterion for a polytope to allow an affirmative answer to the question. 相似文献
20.
Jean Bourgain 《Geometric And Functional Analysis》2009,18(5):1477-1502
The main result of this paper is an exponential sum bound in prime fields for multilinear expressions of the type under nearly optimal conditions on . It provides the expected generalization of the well-known inequality for r = 2. We also establish a new result on Gauss sums for multiplicative subgroups H of , obtaining a nontrivial estimate provided . This is a further improvement on [BGK].
Received: May 2007, Revision: October 2007, Accepted: October 2007 相似文献