共查询到20条相似文献,搜索用时 578 毫秒
1.
D. Blanusa 《Annali di Matematica Pura ed Applicata》1962,57(1):321-337
Summary C∞ — isometric imbeddings of the hyperbolic plane and of the two types of orientable cylinders with hyperbolic metric in spherical8-space are constructed, furthermore C∞ — isometric imbeddings of the non-orientable cylinder with hyperbolic metric in Euclidean8-space and in spherical10-space.
To Enrico Bompiani on his scientific Jubilee. 相似文献
2.
Beniamino Segre 《Annali di Matematica Pura ed Applicata》1959,48(1):1-96
Sunto Studio sistematico di varie proprietà — di carattere algebrico, geometrico ed aritmetico — inerenti agli spazi di Galois.
ossia agli spazi proiettivi sopra un corpo finito.
A Giovanni Sansone nel suo 70mo compleanno. 相似文献
3.
Ansten Mørch Klev 《Archive for Mathematical Logic》2009,48(7):691-703
Using infinite time Turing machines we define two successive extensions of Kleene’s O{\mathcal{O}} and characterize both their height and their complexity. Specifically, we first prove that the one extension—which we will
call O+{\mathcal{O}^{+}}—has height equal to the supremum of the writable ordinals, and that the other extension—which we will call O++{\mathcal{O}}^{++}—has height equal to the supremum of the eventually writable ordinals. Next we prove that O+{\mathcal{O}^+} is Turing computably isomorphic to the halting problem of infinite time Turing computability, and that O++{\mathcal{O}^{++}} is Turing computably isomorphic to the halting problem of eventual computability. 相似文献
4.
Jonatan Vasilis 《Geometriae Dedicata》2011,152(1):51-62
Suppose that n cyclically tangent discs with pairwise disjoint interiors are externally tangent to and surround the unit disc. The sharp
ring lemma in two dimensions states that no disc has a radius below c
n
(R
2) = (F
2n−3−1)−1—where F
k
denotes the kth Fibonacci number—and that the lower bound is attained in essentially unique Apollonian configurations. In this article,
generalizations of the ring lemma to three dimensions are discussed, a version of the ring lemma in three dimensions is proved,
and a natural generalization of the extremal two-dimensional configuration—thought to be extremal in three dimensions—is given.
The sharp three-dimensional ring lemma constant of order n is shown to be bounded from below by the two-dimensional constant of order n − 1. 相似文献
5.
A. V. Greshnov 《Siberian Advances in Mathematics》2010,20(3):164-179
We consider some metric spaces with quasimetric (quasispaces) comprising uniformly regular (equiregular) Carnot — Carathéodory
quasispaces whose quasimetric is induced by C
ϒ−1-smooth vector fields of formal degree not higher than ϒ. For these spaces, some analogues of the Campbell — Hausdorff formula
are derived, which allows us to prove a theorem on a nilpotent tangent cone, a theorem on isomorphism of various nilpotent
tangent cones defined at a common point, and a local approximation theorem. 相似文献
6.
In this paper, we consider the almost everywhere convergenc of Bochner—Riesz means below the critical index in Bessel potential
spacesL
a
p
(1≤p≤2 anda>0) and find out the relation between the index of Bochner—Riesz means and the degree of smoothness of functions. 相似文献
7.
We show that separable, locally compact spaces with property (a) necessarily have countable extent — i.e., have no uncountable
closed, discrete subspaces — if the effective weak diamond principle ⋄(ω,ω,<) holds. If the stronger, non-effective, diamond principle Φ(ω,ω,<) holds then separable, countably paracompact spaces also have countable extent. We also give a short proof that the latter
principle implies there are no small dominating families in
ω
1
ω. 相似文献
8.
Zhan Yinwei 《分析论及其应用》1994,10(2):83-91
In this note we characterize the geometric feature of a (μ;r,k)—FES. Namely, for a Cμ triangular interpolation scheme with Cr vertex data, any angle of the macrotriangle must be divided into at least (μ+1)/(r+1−μ) parts. 相似文献
9.
Neeta Pandey 《Proceedings Mathematical Sciences》1999,109(1):1-10
We define a class of simplicial maps — those which are “expanding directions preserving” — from a barycentric subdivision to the original simplicial complex. These maps naturally induce a self map on the links
of their fixed points. The local index at a fixed point of such a map turns out to be the Lefschetz number of the induced
map on the link of the fixed point in relative homology. We also show that a weakly hyperbolic [4] simplicial map sdnK →K is expanding directions preserving. 相似文献
10.
11.
Generators of some Ramanujan formulas 总被引:2,自引:0,他引:2
Jesús Guillera 《The Ramanujan Journal》2006,11(1):41-48
In this paper we prove some Ramanujan type formulas for 1/π but without using the theory of modular forms. Instead we use
the WZ—method created by H. Wilf and D. Zeilberger and find some hypergeometric functions in two variables which are second
components of WZ—pairs than can be certified using Zeilberger's EKHAD package. These certificates have an additional property
which allows us to get generalized Ramanujan's type series which are routinely proven by computer. We call these second hypergeometric
components of the WZ—pairs generators. Finding generators seems a hard task but using a kind of experimental research (explained
below), we have succeeded in finding some of them. Unfortunately we have not found yet generators for the most impressive
Ramanujan's formulas. We also prove some interesting binomial sums for the constant 1/π2. Finally we rewrite many of the obtained series using pochhammer symbols and study the rate of convergence.
2000 Mathematics Subject Classification Primary—33C20 相似文献
12.
Ernesto Stagni 《Annali di Matematica Pura ed Applicata》1917,26(1):85-94
Sunto. La frequenza di vibrazione libera di un sistema elastico, come il valore del carico critico, può definirsi mediante un rapporto,
ω2, da rendere minimo mediante l'opportuna determinazione di una funzione η (configurazione). I metodi approssimati per la soluzione
di questo problema variazionale — metodo di Ritz e delle successive approssimazioni — possono essere applicati, anche in questo
caso, rappresentando le funzioni η numericamente, con poche differenze rispetto al caso già visto dell' instabilità. Si tratta
di definire un appropriato termine correttivo, per eliminare l'errore dovuto alla discontinuità della rappresentazione numerica,
e di giungere, attraverso un particolare procedimento, a determinare anche i valori delle prime armoniche dopo la frequenza
fondamentale. 相似文献
13.
Ronald L. Lipsman 《Israel Journal of Mathematics》1986,54(3):335-350
It is proven that theL
2 spectrum for certain non-semisimple, non-nilpotent symmetric spaces is multiplicity-free. The spectrum and spectral measure
are computed precisely for symmetric spaces corresponding to non-compact motion groups. Somewhat less complete results on
theL
2 spectrum — in both the Mackey Machine and Orbit Method modes — are given for general semidirect product symmetric spaces.
The author was supported by the NSF through DMS84-00900-A01 and by a Senior Fulbright Fellowship. 相似文献
14.
Given an i.i.d. sample from a probability measure P on ℝ, an estimator is constructed that efficiently estimates P in the bounded-Lipschitz metric for weak convergence of probability measures, and, at the same time, estimates the density
of P — if it exists (but without assuming it does) — at the best possible rate of convergence in total variation loss (that is,
in L
1-loss for densities).
相似文献
15.
Résumé. — Soit μ la mesure d'équilibre d'un endomorphisme de P
k
(C). Nous montrons ici qu'elle est son unique mesure d'entropie maximale. Nous construisons directement μ comme distribution
asymptotique des préimages de tout point hors d'un ensemble exceptionnel algébraique.
Manucsrit re?u le 30 novembre 2000. 相似文献
— Let μ be the equilibrium measure of an endomorphism of P k (C). We show that it is its unique measure of maximal entropy. We build μ directly as the distribution of premiages of any point outside an algebraic exceptional set.
Manucsrit re?u le 30 novembre 2000. 相似文献
16.
Richárd Rimányi 《Inventiones Mathematicae》2001,143(3):499-521
As an application of the generalized Pontryagin-Thom construction [RSz] here we introduce a new method to compute cohomological
obstructions of removing singularities — i.e. Thom polynomials [T]. With the aid of this method we compute some sample results,
such as the Thom polynomials associated to all stable singularities of codimension ≤8 between equal dimensional manifolds,
and some other Thom polynomials associated to singularities of maps N
n
?P
n+k
for k>0. We also give an application by reproving a weak form of the multiple point formulas of Herbert and Ronga ([H], [Ro2]).
As a byproduct of the theory we define the incidence class of singularities, which — the author believes — may turn to be
an interesting, useful and simple tool to study incidences of singularities.
Oblatum 4-II-1999 & 19-VII-2000?Published online: 30 October 2000 相似文献
17.
Carlo Bonferroni 《Annali di Matematica Pura ed Applicata》1959,48(1):387-402
Sunto Definito il flusso d'area attraverso una linea, di volume attraverso una superficie, ecc..., viene definita per analogia —
riferendosi all'ordinaria rappresentazione geometrica di un campo di probabilità — la densità di probabilità come flusso di
probabilità, dandone l'espressione come flusso di un vettore attraverso una linea, o una superficie, ecc..., secondo le dimensioni
del campo di probabilità.
A Giovanni Sansone nel suo 70mo compleanno. 相似文献
18.
Giulio Andreoli 《Annali di Matematica Pura ed Applicata》1960,49(1):97-116
Sunto La genetica mendeliana, depurata da fatti aleatori e da eventuali catene diMarkoff, è riproducibile — come schema matematico — da algebre non associative. Vi è tuttavia, fra queste, un caso eccezionale, trattato
più estesamente in questa memoria.
Interpretando poi le strutture successive di una collettività mendeliana come vettori, questi soddisfano ad un'equazione vettoriale
del tipoRiccati.
A Giovanni Sansone nel suo 70mo compleanno. 相似文献
19.
It is shown that for every 1≤s≤n, the probability that thes-th largest eigenvalue of a random symmetricn-by-n matrix with independent random entries of absolute value at most 1 deviates from its median by more thant is at most 4e
−
t
232
s2. The main ingredient in the proof is Talagrand’s Inequality for concentration of measure in product spaces.
Research supported in part by a USA — Israel BSF grant, by a grant from the Israel Science Foundation and by the Hermann Minkowski
Minerva Center for Geometry at Tel Aviv University.
Research supported in part by a USA — Israel BSF grant and by a Bergmann Memorial Grant. 相似文献
20.
We deal with (n−1)-generated modules of smooth (analytic, holomorphic) vector fieldsV=(X
1,..., Xn−1) (codimension 1 differential systems) defined locally on ℝ
n
or ℂ
n
, and extend the standard duality(X
1,..., Xn−1)↦(ω), ω=Ω(X1,...,Xn−1,.,) (Ω−a volume form) betweenV′s and 1-generated modules of differential 1-forms (Pfaffian equations)—when the generatorsX
i are linearly independent—onto substantially wider classes of codimension 1 differential systems. We prove that two codimension
1 differential systemsV and
are equivalent if and only if so are the corresponding Pfaffian equations (ω) and
provided that ω has1-division property: ωΛμ=0, μ—any 1-form ⇒ μ=fω for certain function germf. The 1-division property of ω turns out to be equivalent to the following properties ofV: (a)fX∈V, f—not a 0-divisor function germ ⇒X∈V (thedivision property); (b) (V
⊥)⊥=V; (c)V
⊥=(ω); (d) (ω)⊥=V, where ⊥ denotes the passing from a module (of vector fields or differential 1-forms) to its annihilator.
Supported by Polish KBN grant No 2 1090 91 01.
Partially supported by the fund for the promotion of research at the Technion, 100–942. 相似文献