Uniform bounds

It is shown that the bilinear Hilbert transforms Hα,β (f, g)(x) = p.v. R f (x − αt)g(x − βt) dt t map Lp1 (R) × Lp2 (R) → Lp (R) uniformly in the real parameters α, β when 2
46p tuanloccuoi 04012013 13 4 Download

Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí hóa hoc quốc tế đề tài : Some limit theorems for the secondorder Markov chains indexed by a general infinite tree with uniform bounded degree
14p sting03 06022012 29 4 Download

We consider the search for a maximum likelihood assignment of hidden derivations and grammar weights for a probabilistic contextfree grammar, the problem approximately solved by “Viterbi training.” We show that solving and even approximating Viterbi training for PCFGs is NPhard. We motivate the use of uniformatrandom initialization for Viterbi EM as an optimal initializer in absence of further information about the correct model parameters, providing an approximate bound on the loglikelihood.
10p hongdo_1 12042013 15 1 Download

Given a bounded valence, bushy tree T , we prove that any cobounded quasiaction of a group G on T is quasiconjugate to an action of G on another bounded valence, bushy tree T . This theorem has many applications: quasiisometric rigidity for fundamental groups of ﬁnite, bushy graphs of coarse PD(n) groups for each ﬁxed n; a generalization to actions on Cantor sets of Sullivan’s theorem about uniformly quasiconformal actions on the 2sphere; and a characterization of locally compact topological groups which contain a virtually free group as a cocompact lattice. ...
51p tuanloccuoi 04012013 17 5 Download

We prove that in every ﬁnitely generated proﬁnite group, every subgroup of ﬁnite index is open; this implies that the topology on such groups is determined by the algebraic structure. This is deduced from the main result about ﬁnite groups: let w be a ‘locally ﬁnite’ group word and d ∈ N. Then there exists f = f (w, d) such that in every dgenerator ﬁnite group G, every element of the verbal subgroup w(G) is equal to a product of f wvalues.
69p noel_noel 17012013 15 5 Download

We prove that Cayley graphs of SL2 (Fp ) are expanders with respect to the projection of any ﬁxed elements in SL(2, Z) generating a nonelementary subgroup, and with respect to generators chosen at random in SL2 (Fp ). 1. Introduction Expanders are highlyconnected sparse graphs widely used in computer science, in areas ranging from parallel computation to complexity theory and cryptography; recently they also have found some remarkable applications in pure mathematics; see [5],[10], [15], [20], [21] and references therein. ...
19p dontetvui 17012013 24 5 Download

For each k ∈ Z, we construct a uniformly contractible metric on Euclidean space which is not mod k hypereuclidean. We also construct a pair of uniformly contractible Riemannian metrics on Rn , n ≥ 11, so that the resulting manifolds Z and Z are bounded homotopy equivalent by a homotopy equivalence which is not boundedly close to a homeomorphism. We show that for these lf spaces the C ∗ algebra assembly map K∗ (Z) → K∗ (C ∗ (Z)) from locally ﬁnite Khomology to the Ktheory of the bounded propagation algebra is not a monomorphism ...
21p tuanloccuoi 04012013 12 5 Download

We present an analysis of boundedenergy lowtension maps between 2spheres. By deriving sharp estimates for the ratio of length scales on which bubbles of opposite orientation develop, we show that we can establish a ‘quantization estimate’ which constrains the energy of the map to lie near to a discrete energy spectrum. One application is to the asymptotics of the harmonic map ﬂow; we ﬁnd uniform exponential convergence in time, in the case under consideration.
71p tuanloccuoi 04012013 21 5 Download

We ﬁnd a sharp combinatorial bound for the metric entropy of sets in Rn and general classes of functions. This solves two basic combinatorial conjectures on the empirical processes. 1. A class of functions satisﬁes the uniform Central Limit Theorem if the square root of its combinatorial dimension is integrable. 2. The uniform entropy is equivalent to the combinatorial dimension under minimal regularity. Our method also constructs a nicely bounded coordinate section of a symmetric convex body in Rn . ...
47p noel_noel 17012013 24 5 Download

There has been much previous work on node localization and event detection [6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16] , includ ing foundational work on theoretical lower bounds [17, 18]. Sex tant differentiates itself from this body of work in several ways. First, it does not assume uniform transmission radii (i.e.
27p nhacsihuytuan 06042013 26 5 Download

There has recendy been a revival of interest in Categorial Grammars (CG) among computational linguists. The various versions noted below which extend pure C G by including operations such as functional composition have been claimed to offer simple and uniform accounts of a wide range of natural language (NL) constructions involving bounded and unbounded "movement" and coordination "reduction" in a number of languages. Such grammars have obvious advantages for computational applications, provided that they can be parsed efficiently.
8p bungio_1 03052013 19 1 Download