5,233 research outputs found
Problems on q-Analogs in Coding Theory
The interest in -analogs of codes and designs has been increased in the
last few years as a consequence of their new application in error-correction
for random network coding. There are many interesting theoretical, algebraic,
and combinatorial coding problems concerning these q-analogs which remained
unsolved. The first goal of this paper is to make a short summary of the large
amount of research which was done in the area mainly in the last few years and
to provide most of the relevant references. The second goal of this paper is to
present one hundred open questions and problems for future research, whose
solution will advance the knowledge in this area. The third goal of this paper
is to present and start some directions in solving some of these problems.Comment: arXiv admin note: text overlap with arXiv:0805.3528 by other author
Covering of Subspaces by Subspaces
Lower and upper bounds on the size of a covering of subspaces in the
Grassmann graph \cG_q(n,r) by subspaces from the Grassmann graph
\cG_q(n,k), , are discussed. The problem is of interest from four
points of view: coding theory, combinatorial designs, -analogs, and
projective geometry. In particular we examine coverings based on lifted maximum
rank distance codes, combined with spreads and a recursive construction. New
constructions are given for with or . We discuss the density
for some of these coverings. Tables for the best known coverings, for and
, are presented. We present some questions concerning
possible constructions of new coverings of smaller size.Comment: arXiv admin note: text overlap with arXiv:0805.352
Measurements of Hadronic Asymmetries in e+e- Collisions
High precision experimental new electroweak results measured at the four LEP
experiments and the SLD collaboration are discussed. Heavy quark (b b-bar and c
c-bar) forward-backward asymmetries measured at LEP are presented along with
polarized forward-backward and left-right asymmetries measured at SLD. The
results are compared, and the combined averages are used to evaluate the
Standard Model parameters.Comment: 8 Pages, 5 eps files, Presented at the International Europhysics
Conference on High Energy Physics, August 1997, Jerusalem, Israe
Experimental Studies of Electroweak Physics
Some experimental new Electroweak physics results measured at the LEP/SLD and
the TEVATRON are discussed. The excellent accuracy achieved by the experiments
still yield no significant evidence for deviation from the Standard Model
predictions, or signal to physics beyond the Standard Model. The Higgs particle
still has not been discovered and a low bound is given to its mass.Comment: 10 pages, 5 figures, Invited talk at "Fundemental Particles and
Interactions", Vanderbilt University, Nashville, Tennessee, May 199
Folding, Tiling, and Multidimensional Coding
Folding a sequence into a multidimensional box is a method that is used
to construct multidimensional codes. The well known operation of folding is
generalized in a way that the sequence can be folded into various shapes.
The new definition of folding is based on lattice tiling and a direction in the
-dimensional grid. There are potentially different folding
operations. Necessary and sufficient conditions that a lattice combined with a
direction define a folding are given. The immediate and most impressive
application is some new lower bounds on the number of dots in two-dimensional
synchronization patterns. This can be also generalized for multidimensional
synchronization patterns. We show how folding can be used to construct
multidimensional error-correcting codes and to generate multidimensional
pseudo-random arrays
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