نتایج جستجو برای: extremal vector
تعداد نتایج: 206102 فیلتر نتایج به سال:
This paper presents new vector filter banks, in particular biorthogonal Hermite cubic multiwavelets with short, smooth duals. We study different preprocessing techniques and the covariance structure of corresponding transforms. Results of numerical experiments in signal denoising and image compression using multi-filters are discussed. We compare the performance of several multi-filters with th...
There are two distinct weight enumerators for extremal singly-even self-dual [36; 18; 8] codes. For each weight enumerator, only one extremal self-dual code is previously known. In this correspondence, we construct several new extremal singly-even self-dual [36; 18; 8] codes for each weight enumerator. We also construct a number of new extremal singly-even self-dual [38; 19; 8] codes.
We construct multi-center solutions for charged, dilatonic, non-extremal black holes in D = 4. When an infinite array of such non-extremal black holes are aligned periodically along an axis, the configuration becomes independent of this coordinate, which can therefore be used for Kaluza-Klein compactification. This generalises the vertical dimensional reduction procedure to include non-extremal...
The automorphism groups of the three known extremal even unimodular lattices of dimension 48 and the one of dimension 72 are determined using the classification of finite simple groups. Restrictions on the possible automorphisms of 48-dimensional extremal lattices are obtained. We classify all extremal lattices of dimension 48 having an automorphism of order m with φ(m) > 24. In particular the ...
We study the phases of near-extremal branes on a circle, by which we mean near-extremal branes of string theory and M-theory with a circle in their transverse space. We find a map that takes any static and neutral Kaluza-Klein black hole, i.e. any static and neutral black hole on Minkowski-space times a circle Md×S1, and map it to a corresponding solution for a near-extremal brane on a circle. ...
Boros and Füredi (for d = 2) and Bárány (for arbitrary d) proved that there exists a positive real number cd such that for every set P of n points in R d in general position, there exists a point of R contained in at least cd ( n d+1 ) d-simplices with vertices at the points of P . Gromov improved the known lower bound on cd by topological means. Using methods from extremal combinatorics, we im...
A stabbing line for a set of convex polyhedra is extremal if it passes through four edges and is tangent to the polyhedra containing those edges. In this paper we present three constructions of convex polyhedra with many extremal lines. The rst construction shows (n 2) extremal stabbing lines constrained to meet two skew lines. The second shows (n 4) extremal lines which are tangent to two poly...
We give several pieces of evidence to show that extremal black holes cannot be obtained as limits of non-extremal black holes. We review arguments in the literature showing that the entropy of extremal black holes is zero, while that of near-extremal ones obey the Bekenstein-Hawking formula. However, from the counting of degeneracy of quantum (BPS) states of string theory the entropy of extrema...
In this paper, new binary extremal self-dual codes are presented. A number of new extremal singly-even self-dual codes of lengths 48; 64 and 78, and extremal doubly-even self-dual codes of lengths 80 and 88, are constructed. We also relate an extremal doubly-even self-dual code of length divisible by 24 to an extremal singly-even self-dual code of that length. New singly-even self-dual codes of...
We show that certain geometrically defined higher codimension cycles are extremal in the effective cone of the moduli spaceMg,n of stable genus g curves with n ordered marked points. In particular, we prove that codimension two boundary strata are extremal and exhibit extremal boundary strata of higher codimension. We also show that the locus of hyperelliptic curves with a marked Weierstrass po...
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