64,031 research outputs found
Computing Extensions of Linear Codes
This paper deals with the problem of increasing the minimum distance of a
linear code by adding one or more columns to the generator matrix. Several
methods to compute extensions of linear codes are presented. Many codes
improving the previously known lower bounds on the minimum distance have been
found.Comment: accepted for publication at ISIT 0
Powerful sets: a generalisation of binary matroids
A set of binary vectors, with positions indexed by ,
is said to be a \textit{powerful code} if, for all , the number
of vectors in that are zero in the positions indexed by is a power of
2. By treating binary vectors as characteristic vectors of subsets of , we
say that a set of subsets of is a \textit{powerful set} if
the set of characteristic vectors of sets in is a powerful code. Powerful
sets (codes) include cocircuit spaces of binary matroids (equivalently, linear
codes over ), but much more besides. Our motivation is that, to
each powerful set, there is an associated nonnegative-integer-valued rank
function (by a construction of Farr), although it does not in general satisfy
all the matroid rank axioms.
In this paper we investigate the combinatorial properties of powerful sets.
We prove fundamental results on special elements (loops, coloops, frames,
near-frames, and stars), their associated types of single-element extensions,
various ways of combining powerful sets to get new ones, and constructions of
nonlinear powerful sets. We show that every powerful set is determined by its
clutter of minimal nonzero members. Finally, we show that the number of
powerful sets is doubly exponential, and hence that almost all powerful sets
are nonlinear.Comment: 19 pages. This work was presented at the 40th Australasian Conference
on Combinatorial Mathematics and Combinatorial Computing (40ACCMCC),
University of Newcastle, Australia, Dec. 201
A Pseudo DNA Cryptography Method
The DNA cryptography is a new and very promising direction in cryptography
research. DNA can be used in cryptography for storing and transmitting the
information, as well as for computation. Although in its primitive stage, DNA
cryptography is shown to be very effective. Currently, several DNA computing
algorithms are proposed for quite some cryptography, cryptanalysis and
steganography problems, and they are very powerful in these areas. However, the
use of the DNA as a means of cryptography has high tech lab requirements and
computational limitations, as well as the labor intensive extrapolation means
so far. These make the efficient use of DNA cryptography difficult in the
security world now. Therefore, more theoretical analysis should be performed
before its real applications.
In this project, We do not intended to utilize real DNA to perform the
cryptography process; rather, We will introduce a new cryptography method based
on central dogma of molecular biology. Since this method simulates some
critical processes in central dogma, it is a pseudo DNA cryptography method.
The theoretical analysis and experiments show this method to be efficient in
computation, storage and transmission; and it is very powerful against certain
attacks. Thus, this method can be of many uses in cryptography, such as an
enhancement insecurity and speed to the other cryptography methods. There are
also extensions and variations to this method, which have enhanced security,
effectiveness and applicability.Comment: A small work that quite some people asked abou
Ideal codes over separable ring extensions
This paper investigates the application of the theoretical algebraic notion
of a separable ring extension, in the realm of cyclic convolutional codes or,
more generally, ideal codes. We work under very mild conditions, that cover all
previously known as well as new non trivial examples. It is proved that ideal
codes are direct summands as left ideals of the underlying non-commutative
algebra, in analogy with cyclic block codes. This implies, in particular, that
they are generated by an idempotent element. Hence, by using a suitable
separability element, we design an efficient algorithm for computing one of
such idempotents
Lattices from Codes for Harnessing Interference: An Overview and Generalizations
In this paper, using compute-and-forward as an example, we provide an
overview of constructions of lattices from codes that possess the right
algebraic structures for harnessing interference. This includes Construction A,
Construction D, and Construction (previously called product
construction) recently proposed by the authors. We then discuss two
generalizations where the first one is a general construction of lattices named
Construction subsuming the above three constructions as special cases
and the second one is to go beyond principal ideal domains and build lattices
over algebraic integers
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