1,269 research outputs found
Generalizations of the Kolmogorov-Barzdin embedding estimates
We consider several ways to measure the `geometric complexity' of an
embedding from a simplicial complex into Euclidean space. One of these is a
version of `thickness', based on a paper of Kolmogorov and Barzdin. We prove
inequalities relating the thickness and the number of simplices in the
simplicial complex, generalizing an estimate that Kolmogorov and Barzdin proved
for graphs. We also consider the distortion of knots. We give an alternate
proof of a theorem of Pardon that there are isotopy classes of knots requiring
arbitrarily large distortion. This proof is based on the expander-like
properties of arithmetic hyperbolic manifolds.Comment: 45 page
Approximation of smooth functions on compact two-point homogeneous spaces
Estimates of Kolmogorov -widths and linear -widths
\da_n(B_p^r, L^q), () of Sobolev's classes ,
(, ) on compact two-point homogeneous spaces (CTPHS)
are established. For part of , sharp
orders of or \da_n (B_p^r, L^q) were obtained by Bordin,
Kushpel, Levesley and Tozoni in a recent paper `` J. Funct. Anal. 202 (2)
(2003), 307--326''. In this paper, we obtain the sharp orders of and \da_n (B_p^r, L^q) for all the remaining . Our proof is
based on positive cubature formulas and Marcinkiewicz-Zygmund type inequalities
on CTPHS
Estimates of n-widths of Sobolev's classes on compact globally symmetric spaces of rank one
AbstractEstimates of Kolmogorov's and linear n-widths of Sobolev's classes on compact globally symmetric spaces of rank 1 (i.e. on Sd, Pd(R), Pd(C), Pd(H), P16(Cay)) are established. It is shown that these estimates have sharp orders in different important cases. New estimates for the (p,q)-norms of multiplier operators Λ={λk}k∈N are given. We apply our results to get sharp orders of best polynomial approximation and n-widths
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