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math/0010307
Fields, towers of function fields meeting asymptotic bounds, and basis constructions for algebraic-geometric codes
math.NT cs.IT math.IT
In this work, we use the notion of ``symmetry'' of functions for an extension $K/L$ of finite fields to produce extensions of a function field $F/K$ in which almost all places of degree one split completely. Then we introduce the notion of ``quasi-symmetry'' of functions for $K/L$, and demonstrate its use in producin...
math/0012163
Learning Complexity Dimensions for a Continuous-Time Control System
math.OC cs.LG
This paper takes a computational learning theory approach to a problem of linear systems identification. It is assumed that input signals have only a finite number k of frequency components, and systems to be identified have dimension no greater than n. The main result establishes that the sample complexity needed fo...
math/0101092
Structure of $Z^2$ modulo selfsimilar sublattices
math.CO cs.IT math.IT
In this paper we show the combinatorial structure of $\mathbb{Z}^2$ modulo sublattices selfsimilar to $\mathbb{Z}^2$. The tool we use for dealing with this purpose is the notion of association scheme. We classify when the scheme defined by the lattice is imprimitive and characterize its decomposition in terms of the ...
math/0103007
Source Coding, Large Deviations, and Approximate Pattern Matching
math.PR cs.IT math.IT
We present a development of parts of rate-distortion theory and pattern- matching algorithms for lossy data compression, centered around a lossy version of the Asymptotic Equipartition Property (AEP). This treatment closely parallels the corresponding development in lossless compression, a point of view that was adva...
math/0103107
Explicit modular towers
math.NT cs.IT math.AG math.IT
We give a general recipe for explicitly constructing asymptotically optimal towers of modular curves such as {X_0(l^n): n=1,2,3,...}. We illustrate the method by giving equations for eight towers with various geometric features. We conclude by observing that such towers are all of a specific recursive form, and specu...
math/0103109
In search of an evolutionary coding style
math.NA cs.IT math.DS math.IT q-bio
In the near future, all the human genes will be identified. But understanding the functions coded in the genes is a much harder problem. For example, by using block entropy, one has that the DNA code is closer to a random code then written text, which in turn is less ordered then an ordinary computer code; see \cite{...
math/0104016
Bounds for weight distribution of weakly self-dual codes
math.CO cs.IT math.IT quant-ph
Upper bounds are given for the weight distribution of binary weakly self-dual codes. To get these new bounds, we introduce a novel method of utilizing unitary operations on Hilbert spaces. This method is motivated by recent progress on quantum computing. This new approach leads to much simpler proofs for such genre o...
math/0104115
Excellent nonlinear codes from modular curves
math.NT cs.IT math.AG math.IT
We introduce a new construction of error-correcting codes from algebraic curves over finite fields. Modular curves of genus g -> infty over a field of size q0^2 yield nonlinear codes more efficient than the linear Goppa codes obtained from the same curves. These new codes now have the highest asymptotic transmission ...
math/0104222
Decoding method for generalized algebraic geometry codes
math.NT cs.IT math.AG math.IT
We propose a decoding method for the generalized algebraic geometry codes proposed by Xing et al. To show its practical usefulness, we give an example of generalized algebraic geometry codes of length 567 over F_8 whose numbers of correctable errors by the proposed method are larger than the shortened codes of the pr...
math/0105235
Mathematics of learning
math.PR cs.LG math.CO math.DS
We study the convergence properties of a pair of learning algorithms (learning with and without memory). This leads us to study the dominant eigenvalue of a class of random matrices. This turns out to be related to the roots of the derivative of random polynomials (generated by picking their roots uniformly at random...
math/0105236
Harmonic mean, random polynomials and stochastic matrices
math.PR cs.LG math.CA math.CO math.DS
Motivated by a problem in learning theory, we are led to study the dominant eigenvalue of a class of random matrices. This turns out to be related to the roots of the derivative of random polynomials (generated by picking their roots uniformly at random in the interval [0, 1], although our results extend to other dis...
math/0106089
The coset weight distributions of certain BCH codes and a family of curves
math.AG cs.IT math.CO math.IT
We study the distribution of the number of rational points in a family of curves over a finite field of characteristic 2. This distribution determines the coset weight distribution of a certain BCH code.
math/0108096
Geometrically Uniform Frames
math.FA cs.IT math.GR math.IT
We introduce a new class of frames with strong symmetry properties called geometrically uniform frames (GU), that are defined over an abelian group of unitary matrices and are generated by a single generating vector. The notion of GU frames is then extended to compound GU (CGU) frames which are generated by an abelia...
math/0110157
Some Applications of Algebraic Curves to Computational Vision
math.AG cs.IT math.IT
We introduce a new formalism and a number of new results in the context of geometric computational vision. The classical scope of the research in geometric computer vision is essentially limited to static configurations of points and lines in $P^3$ . By using some well known material from algebraic geometry, we open ...
math/0110214
Coding Distributive Lattices with Edge Firing Games
math.CO cs.IT math-ph math.DS math.IT math.MP
In this note, we show that any distributive lattice is isomorphic to the set of reachable configurations of an Edge Firing Game. Together with the result of James Propp, saying that the set of reachable configurations of any Edge Firing Game is always a distributive lattice, this shows that the two concepts are equiv...
math/0111159
Constructing elliptic curves with a known number of points over a prime field
math.NT cs.IT math.AG math.IT
Elliptic curves with a known number of points over a given prime field with n elements are often needed for use in cryptography. In the context of primality proving, Atkin and Morain suggested the use of the theory of complex multiplication to construct such curves. One of the steps in this method is the calculation ...
math/0112216
Classification of Finite Dynamical Systems
math.DS cs.MA math.CO
This paper is motivated by the theory of sequential dynamical systems, developed as a basis for a mathematical theory of computer simulation. It contains a classification of finite dynamical systems on binary strings, which are obtained by composing functions defined on the coordinates. The classification is in terms...
math/0202276
A numerical method for solution of ordinary differential equations of fractional order
math.NA cs.CE physics.comp-ph
In this paper we propose an algorithm for the numerical solution of arbitrary differential equations of fractional order. The algorithm is obtained by using the following decomposition of the differential equation into a system of differential equation of integer order connected with inverse forms of Abel-integral eq...
math/0203059
On linear programming bounds for spherical codes and designs
math.CO cs.IT math.IT math.OC
We investigate universal bounds on spherical codes and spherical designs that could be obtained using Delsarte's linear programming methods. We give a lower estimate for the LP upper bound on codes, and an upper estimate for the LP lower bound on designs. Specifically, when the distance of the code is fixed and the d...
math/0205218
A New Operation on Sequences: the Boustrouphedon Transform
math.CO cs.IT math.IT
A generalization of the Seidel-Entringer-Arnold method for calculating the alternating permutation numbers (or secant-tangent numbers) leads to a new operation on integer sequences, the Boustrophedon transform.
math/0205299
The Lattice of N-Run Orthogonal Arrays
math.CO cs.IT math.IT
If the number of runs in a (mixed-level) orthogonal array of strength 2 is specified, what numbers of levels and factors are possible? The collection of possible sets of parameters for orthogonal arrays with N runs has a natural lattice structure, induced by the ``expansive replacement'' construction method. In parti...
math/0205301
Some Canonical Sequences of Integers
math.CO cs.IT math.IT
Extending earlier work of R. Donaghey and P. J. Cameron, we investigate some canonical "eigen-sequences" associated with transformations of integer sequences. Several known sequences appear in a new setting: for instance the sequences (such as 1, 3, 11, 49, 257, 1531, ...) studied by T. Tsuzuku, H. O. Foulkes and A. ...
math/0205303
On Asymmetric Coverings and Covering Numbers
math.CO cs.IT math.IT
An asymmetric covering D(n,R) is a collection of special subsets S of an n-set such that every subset T of the n-set is contained in at least one special S with |S| - |T| <= R. In this paper we compute the smallest size of any D(n,1) for n <= 8. We also investigate ``continuous'' and ``banded'' versions of the proble...
math/0207121
The Shannon-McMillan Theorem for Ergodic Quantum Lattice Systems
math.DS cs.DS cs.IT math-ph math.IT math.MP math.OA quant-ph
We formulate and prove a quantum Shannon-McMillan theorem. The theorem demonstrates the significance of the von Neumann entropy for translation invariant ergodic quantum spin systems on n-dimensional lattices: the entropy gives the logarithm of the essential number of eigenvectors of the system on large boxes. The on...
math/0207146
A Zador-Like Formula for Quantizers Based on Periodic Tilings
math.CO cs.IT math.IT
We consider Zador's asymptotic formula for the distortion-rate function for a variable-rate vector quantizer in the high-rate case. This formula involves the differential entropy of the source, the rate of the quantizer in bits per sample, and a coefficient G which depends on the geometry of the quantizer but is inde...
math/0207147
Quantizing Using Lattice Intersections
math.CO cs.IT math.IT
The usual quantizer based on an n-dimensional lattice L maps a point x in R^n to a closest lattice point. Suppose L is the intersection of lattices L_1, ..., L_r. Then one may instead combine the information obtained by simultaneously quantizing x with respect to each of the L_i. This corresponds to decomposing R^n i...
math/0207186
A Simple Construction for the Barnes-Wall Lattices
math.CO cs.IT math.IT
A certain family of orthogonal groups (called "Clifford groups" by G. E. Wall) has arisen in a variety of different contexts in recent years. These groups have a simple definition as the automorphism groups of certain generalized Barnes-Wall lattices. This leads to an especially simple construction for the usual Barn...
math/0207197
On Single-Deletion-Correcting Codes
math.CO cs.IT math.IT
This paper gives a brief survey of binary single-deletion-correcting codes. The Varshamov-Tenengolts codes appear to be optimal, but many interesting unsolved problems remain. The connections with shift-register sequences also remain somewhat mysterious.
math/0207208
The Z_4-Linearity of Kerdock, Preparata, Goethals and Related Codes
math.CO cs.IT math.IT
Certain notorious nonlinear binary codes contain more codewords than any known linear code. These include the codes constructed by Nordstrom-Robinson, Kerdock, Preparata, Goethals, and Delsarte-Goethals. It is shown here that all these codes can be very simply constructed as binary images under the Gray map of linear...
math/0207209
Interleaver Design for Turbo Codes
math.CO cs.IT math.IT
The performance of a Turbo code with short block length depends critically on the interleaver design. There are two major criteria in the design of an interleaver: the distance spectrum of the code and the correlation between the information input data and the soft output of each decoder corresponding to its parity b...
math/0207256
The Sphere-Packing Problem
math.CO cs.IT math.IT
A brief report on recent work on the sphere-packing problem.
math/0207291
On Kissing Numbers in Dimensions 32 to 128
math.CO cs.IT math.IT
An elementary construction using binary codes gives new record kissing numbers in dimensions from 32 to 128.
math/0208001
Self-Dual Codes
math.CO cs.IT math.IT
Self-dual codes are important because many of the best codes known are of this type and they have a rich mathematical theory. Topics covered in this survey include codes over F_2, F_3, F_4, F_q, Z_4, Z_m, shadow codes, weight enumerators, Gleason-Pierce theorem, invariant theory, Gleason theorems, bounds, mass formul...
math/0208017
Packing Planes in Four Dimensions and Other Mysteries
math.CO cs.IT math.IT
How should you choose a good set of (say) 48 planes in four dimensions? More generally, how do you find packings in Grassmannian spaces? In this article I give a brief introduction to the work that I have been doing on this problem in collaboration with A. R. Calderbank, J. H. Conway, R. H. Hardin, E. M. Rains and P....
math/0208155
Toric codes over finite fields
math.AG cs.IT math.CO math.IT
In this note, a class of error-correcting codes is associated to a toric variety associated to a fan defined over a finite field $\fff_q$, analogous to the class of Goppa codes associated to a curve. For such a ``toric code'' satisfying certain additional conditions, we present an efficient decoding algorithm for the...
math/0209407
Uniformly distributed sequences of p-adic integers, II
math.NT cs.IT math.DS math.IT
The paper describes ergodic (with respect to the Haar measure) functions in the class of all functions, which are defined on (and take values in) the ring of p-adic integers, and which satisfy (at least, locally) Lipschitz condition with coefficient 1. Equiprobable (in particular, measure-preserving) functions of thi...
math/0210018
Topological robotics: motion planning in projective spaces
math.AT cs.RO math.DG
We study an elementary problem of topological robotics: rotation of a line, which is fixed by a revolving joint at a base point: one wants to bring the line from its initial position to a final position by a continuous motion in the space. The final goal is to construct an algorithm which will perform this task once ...
math/0210115
Topological Robotics: Subspace Arrangements and Collision Free Motion Planning
math.AT cs.RO math.DG
We study an elementary problem of the topological robotics: collective motion of a set of $n$ distinct particles which one has to move from an initial configuration to a final configuration, with the requirement that no collisions occur in the process of motion. The ultimate goal is to construct an algorithm which wi...
math/0210408
Representations of finite groups on Riemann-Roch spaces
math.AG cs.IT math.GR math.IT
We study the action of a finite group on the Riemann-Roch space of certain divisors on a curve. If $G$ is a finite subgroup of the automorphism group of a projective curve $X$ over an algebraically closed field and $D$ is a divisor on $X$ left stable by $G$ then we show the irreducible constituents of the natural rep...
math/0211040
On cyclic convolutional codes
math.RA cs.IT math.CO math.IT
We investigate the notion of cyclicity for convolutional codes as it has been introduced by Piret and Roos in the seventies. Codes of this type are described as submodules of the module of all vector polynomials in one variable with some additional generalized cyclic structure but also as specific left ideals in a sk...
math/0211107
On Near-MDS Elliptic Codes
math.AG cs.IT math.CO math.IT
The main conjecture on maximum distance separable (MDS) codes states that, execpt for some special cases, the maximum length of a q-ary linear MDS code is q+1. This conjecture does not hold true for near maximum distance separable codes because of the existence of q-ary near MDS elliptic codes having length bigger th...
math/0211269
On ASGS framework: general requirements and an example of implementation
math.CO cs.CR cs.DM cs.IT math.IT
In the paper we propose general framework for Automatic Secret Generation and Sharing (ASGS) that should be independent of underlying secret sharing scheme. ASGS allows to prevent the dealer from knowing the secret or even to eliminate him at all. Two situations are discussed. First concerns simultaneous generation a...
math/0212038
A Goppa-like bound on the trellis state complexity of algebraic geometric codes
math.AG cs.IT math.IT
For a linear code $\cC$ of length $n$ and dimension $k$, Wolf noticed that the trellis state complexity $s(\cC)$ of $\cC$ is upper bounded by $w(\cC):=\min(k,n-k)$. In this paper we point out some new lower bounds for $s(\cC)$. In particular, if $\cC$ is an Algebraic Geometric code, then $s(\cC)\geq w(\cC)-(g-a)$, wh...
math/0212212
Coverage control for mobile sensing networks
math.OC cs.IT math.IT
This paper presents control and coordination algorithms for groups of vehicles. The focus is on autonomous vehicle networks performing distributed sensing tasks where each vehicle plays the role of a mobile tunable sensor. The paper proposes gradient descent algorithms for a class of utility functions which encode op...
math/0301135
Grassmannian Frames with Applications to Coding and Communication
math.FA cs.IT math.IT
For a given class ${\cal F}$ of uniform frames of fixed redundancy we define a Grassmannian frame as one that minimizes the maximal correlation $|< f_k,f_l >|$ among all frames $\{f_k\}_{k \in {\cal I}} \in {\cal F}$. We first analyze finite-dimensional Grassmannian frames. Using links to packings in Grassmannian spa...
math/0301268
Improving Search Algorithms by Using Intelligent Coordinates
math.OC cond-mat.stat-mech cs.MA nlin.AO
We consider the problem of designing a set of computational agents so that as they all pursue their self-interests a global function G of the collective system is optimized. Three factors govern the quality of such design. The first relates to conventional exploration-exploitation search algorithms for finding the ma...
math/0302043
Extended visual cryptography systems
math.CO cs.IT math.IT
Visual cryptography schemes have been introduced in 1994 by Naor and Shamir. Their idea was to encode a secret image into $n$ shadow images and to give exactly one such shadow image to each member of a group $P$ of $n$ persons. Whereas most work in recent years has been done concerning the problem of qualified and fo...
math/0302132
Computing Symmetrized Weight Enumerators for Lifted Quadratic Residue Codes
math.CO cs.IT math.IT
The paper describes a method to determine symmetrized weight enumerators of $p^m$-linear codes based on the notion of a disjoint weight enumerator. Symmetrized weight enumerators are given for the lifted quadratic residue codes of length 24 modulo $2^m$ and modulo $3^m$, for any positive $m$.
math/0302154
Twisted Klein curves modulo 2
math.NT cs.IT math.AG math.IT
We give an explicit description of all 168 quartic curves over the field of two elements that are isomorphic to the Klein curve over an algebraic extension. Some of the curves have been known for their small class number, others for attaining the maximal number of rational points.
math/0302172
Results on zeta functions for codes
math.CO cs.IT math.IT math.NT
We give a new and short proof of the Mallows-Sloane upper bound for self-dual codes. We formulate a version of Greene's theorem for normalized weight enumerators. We relate normalized rank-generating polynomials to two-variable zeta functions. And we show that a self-dual code has the Clifford property, but that the ...
math/0303104
Bounding the trellis state complexity of algebraic geometric codes
math.AG cs.IT math.IT
Let C be an algebraic geometric code of dimension k and length n constructed on a curve X over $F_q$. Let s(C) be the state complexity of C and set w(C):=min{k,n-k}, the Wolf upper bound on s(C). We introduce a numerical function R that depends on the gonality sequence of X and show that s(C)\geq w(C)-R(2g-2), where ...
math/0303254
Strongly MDS Convolutional Codes
math.RA cs.IT math.IT math.OC
MDS convolutional codes have the property that their free distance is maximal among all codes of the same rate and the same degree. In this paper we introduce a class of MDS convolutional codes whose column distances reach the generalized Singleton bound at the earliest possible instant. We call these codes strongly ...
math/0304192
On reconstructing n-point configurations from the distribution of distances or areas
math.AC cs.CV cs.SC
One way to characterize configurations of points up to congruence is by considering the distribution of all mutual distances between points. This paper deals with the question if point configurations are uniquely determined by this distribution. After giving some counterexamples, we prove that this is the case for th...
math/0304283
Whitehead method and Genetic Algorithms
math.GR cs.NE cs.SC
In this paper we discuss a genetic version (GWA) of the Whitehead's algorithm, which is one of the basic algorithms in combinatorial group theory. It turns out that GWA is surprisingly fast and outperforms the standard Whitehead's algorithm in free groups of rank >= 5. Experimenting with GWA we collected an interesti...
math/0304292
The Ubiquity of Order Domains for the Construction of Error Control Codes
math.AC cs.IT math.AG math.IT math.RA
The order domains are a class of commutative rings introduced by H{\o}holdt, van Lint, and Pellikaan to simplify the theory of error control codes using ideas from algebraic geometry. The definition is largely motivated by the structures utilized in the Berlekamp-Massey-Sakata (BMS) decoding algorithm, with Feng-Rao ...
math/0304306
Genetic algorithms and the Andrews-Curtis conjecture
math.GR cs.NE cs.SC
The Andrews-Curtis conjecture claims that every balanced presentation of the trivial group can be transformed into the trivial presentation by a finite sequence of "elementary transformations" which are Nielsen transformations together with an arbitrary conjugation of a relator. It is believed that the Andrews-Curtis...
math/0305121
Robust Estimators under the Imprecise Dirichlet Model
math.PR cs.IT cs.LG math.IT math.ST stat.TH
Walley's Imprecise Dirichlet Model (IDM) for categorical data overcomes several fundamental problems which other approaches to uncertainty suffer from. Yet, to be useful in practice, one needs efficient ways for computing the imprecise=robust sets or intervals. The main objective of this work is to derive exact, cons...
math/0305135
Distance bounds for convolutional codes and some optimal codes
math.RA cs.IT math.IT math.OC
After a discussion of the Griesmer and Heller bound for the distance of a convolutional code we present several codes with various parameters, over various fields, and meeting the given distance bounds. Moreover, the Griesmer bound is used for deriving a lower bound for the field size of an MDS convolutional code and...
math/0305308
Numerical Analogues of Aronson's Sequence
math.NT cs.IT math.IT
Aronson's sequence 1, 4, 11, 16, ... is defined by the English sentence ``t is the first, fourth, eleventh, sixteenth, ... letter of this sentence.'' This paper introduces some numerical analogues, such as: a(n) is taken to be the smallest positive integer greater than a(n-1) which is consistent with the condition ``...
math/0306354
Coding and tiling of Julia sets for subhyperbolic rational maps
math.DS cs.IT math.IT
Let $f:\hat{C}\to\hat{C}$ be a subhyperbolic rational map of degree $d$. We construct a set of coding maps $Cod(f)=\{\pi_r:\Sigma\to J\}_r$ of the Julia set $J$ by geometric coding trees, where the parameter $r$ ranges over mappings from a certain tree to the Riemann sphere. Using the universal covering space $\phi:\...
math/0306395
Sur la non-linearite des fonctions booleennes
math.NT cs.IT math.IT
Boolean functions on the space $F_{2}^m$ are not only important in the theory of error-correcting codes, but also in cryptography, where they occur in private key systems. In these two cases, the nonlinearity of these function is a main concept. In this article, I show that the spectral amplitude of boolean functions...
math/0307064
The Number of Hierarchical Orderings
math.CO cs.IT math.IT
An ordered set-partition (or preferential arrangement) of n labeled elements represents a single ``hierarchy''; these are enumerated by the ordered Bell numbers. In this note we determine the number of ``hierarchical orderings'' or ``societies'', where the n elements are first partitioned into m <= n subsets and a hi...
math/0307196
Convolutional Codes with Maximum Distance Profile
math.OC cs.IT math.IT math.RA
Maximum distance profile codes are characterized by the property that two trajectories which start at the same state and proceed to a different state will have the maximum possible distance from each other relative to any other convolutional code of the same rate and degree. In this paper we use methods from system...
math/0308046
Still better nonlinear codes from modular curves
math.NT cs.IT math.AG math.IT
We give a new construction of nonlinear error-correcting codes over suitable finite fields k from the geometry of modular curves with many rational points over k, combining two recent improvements on Goppa's construction. The resulting codes are asymptotically the best currently known.
math/0308110
Sphere packing bounds in the Grassmann and Stiefel manifolds
math.MG cs.IT math.IT
Applying the Riemann geometric machinery of volume estimates in terms of curvature, bounds for the minimal distance of packings/codes in the Grassmann and Stiefel manifolds will be derived and analyzed. In the context of space-time block codes this leads to a monotonically increasing minimal distance lower bound as a...
math/0308153
Mathematics and Logic as Information Compression by Multiple Alignment, Unification and Search
math.GM cs.AI math.LO
This article introduces the conjecture that "mathematics, logic and related disciplines may usefully be understood as information compression (IC) by 'multiple alignment', 'unification' and 'search' (ICMAUS)". As a preparation for the two main sections of the article, concepts of information and information compres...
math/0309081
Asymmetric binary covering codes
math.CO cs.IT math.IT
An asymmetric binary covering code of length n and radius R is a subset C of the n-cube Q_n such that every vector x in Q_n can be obtained from some vector c in C by changing at most R 1's of c to 0's, where R is as small as possible. K^+(n,R) is defined as the smallest size of such a code. We show K^+(n,R) is of or...
math/0309120
An invariant of finitary codes with finite expected square root coding length
math.PR cs.IT math.IT
Let $p$ and $q$ be probability vectors with the same entropy $h$. Denote by $B(p)$ the Bernoulli shift indexed by $\Z$ with marginal distribution $p$. Suppose that $\phi$ is a measure preserving homomorphism from $B(p)$ to $B(q)$. We prove that if the coding length of $\phi$ has a finite 1/2 moment, then $\sigma_p^2=...
math/0309123
Error Correcting Codes on Algebraic Surfaces
math.NT cs.IT math.AG math.IT
Error correcting codes are defined and important parameters for a code are explained. Parameters of new codes constructed on algebraic surfaces are studied. In particular, codes resulting from blowing up points in $\proj^2$ are briefly studied, then codes resulting from ruled surfaces are covered. Codes resulting fro...
math/0309285
An Algorithm for Optimal Partitioning of Data on an Interval
math.NA astro-ph cs.CE cs.DS cs.IT math.CO math.IT
Many signal processing problems can be solved by maximizing the fitness of a segmented model over all possible partitions of the data interval. This letter describes a simple but powerful algorithm that searches the exponentially large space of partitions of $N$ data points in time $O(N^2)$. The algorithm is guarante...
math/0309389
Approximate Squaring
math.NT cs.IT math.IT
We study the ``approximate squaring'' map f(x) := x ceiling(x) and its behavior when iterated. We conjecture that if f is repeatedly applied to a rational number r = l/d > 1 then eventually an integer will be reached. We prove this when d=2, and provide evidence that it is true in general by giving an upper bound on ...
math/0309425
Algebraic Aspects of Multiple Zeta Values
math.QA cs.IT math.IT math.NT
Multiple zeta values have been studied by a wide variety of methods. In this article we summarize some of the results about them that can be obtained by an algebraic approach. This involves "coding" the multiple zeta values by monomials in two noncommuting variables x and y. Multiple zeta values can then be thought o...
math/0310148
Convolutional Codes of Goppa Type
math.OC cs.IT math.AG math.IT
A new kind of Convolutional Codes generalizing Goppa Codes is proposed. This provides a systematic method for constructing convolutional codes with prefixed properties. In particular, examples of Maximum-Distance Separable (MDS) convolutional codes are obtained.
math/0310149
Convolutional Goppa Codes
math.OC cs.IT math.AG math.IT
We define Convolutional Goppa Codes over algebraic curves and construct their corresponding dual codes. Examples over the projective line and over elliptic curves are described, obtaining in particular some Maximum-Distance Separable (MDS) convolutional codes.
math/0310385
De Bruijn Cycles for Covering Codes
math.CO cs.IT math.IT
A de Bruijn covering code is a q-ary string S so that every q-ary string is at most R symbol changes from some n-word appearing consecutively in S. We introduce these codes and prove that they can have length close to the smallest possible covering code. The proof employs tools from field theory, probability, and lin...
math/0311004
Which Point Configurations are Determined by the Distribution of their Pairwise Distances?
math.MG cs.CV math.AC math.AG
In a previous paper we showed that, for any $n \ge m+2$, most sets of $n$ points in $\RR^m$ are determined (up to rotations, reflections, translations and relabeling of the points) by the distribution of their pairwise distances. But there are some exceptional point configurations which are not reconstructible from t...
math/0311046
Codes and Invariant Theory
math.NT cs.IT math.IT
The main theorem in this paper is a far-reaching generalization of Gleason's theorem on the weight enumerators of codes which applies to arbitrary-genus weight enumerators of self-dual codes defined over a large class of finite rings and modules. The proof of the theorem uses a categorical approach, and will be the s...
math/0311129
Cayley-Bacharach and evaluation codes on complete intersections
math.AG cs.IT math.AC math.IT
In recent work, J. Hansen uses cohomological methods to find a lower bound for the minimum distance of an evaluation code determined by a reduced complete intersection in the projective plane. In this paper, we generalize Hansen's results from P^2 to P^m; we also show that the hypotheses in Hansen's work may be weake...
math/0311289
Complete Weight Enumerators of Generalized Doubly-Even Self-Dual Codes
math.NT cs.IT math.IT
For any q which is a power of 2 we describe a finite subgroup of the group of invertible complex q by q matrices under which the complete weight enumerators of generalized doubly-even self-dual codes over the field with q elements are invariant. An explicit description of the invariant ring and some applications to...
math/0311319
Modular and p-adic cyclic codes
math.CO cs.IT math.IT
This paper presents some basic theorems giving the structure of cyclic codes of length n over the ring of integers modulo p^a and over the p-adic numbers, where p is a prime not dividing n. An especially interesting example is the 2-adic cyclic code of length 7 with generator polynomial X^3 + lambda X^2 + (lambda - 1...
math/0312092
On the Parameters of Convolutional Codes with Cyclic Structure
math.RA cs.IT math.CO math.IT
In this paper convolutional codes with cyclic structure will be investigated. These codes can be understood as left principal ideals in a suitable skew-polynomial ring. It has been shown in [3] that only certain combinations of the parameters (field size, length, dimension, and Forney indices) can occur for cyclic co...
math/0401045
Unitary Space Time Constellation Analysis: An Upper Bound for the Diversity
math.CO cs.IT math.IT
The diversity product and the diversity sum are two very important parameters for a good-performing unitary space time constellation. A basic question is what the maximal diversity product (or sum) is. In this paper we are going to derive general upper bounds on the diversity sum and the diversity product for unitary...
math/0401157
Generalized PSK in Space Time Coding
math.CO cs.IT math.IT math.OC
A wireless communication system using multiple antennas promises reliable transmission under Rayleigh flat fading assumptions. Design criteria and practical schemes have been presented for both coherent and non-coherent communication channels. In this paper we generalize one dimensional phase shift keying (PSK) signa...
math/0401279
Backward Optimized Orthogonal Matching Pursuit
math.GM cs.IT math.IT
A recursive approach for shrinking coefficients of an atomic decomposition is proposed. The corresponding algorithm evolves so as to provide at each iteration a) the orthogonal projection of a signal onto a reduced subspace and b) the index of the coefficient to be disregarded in order to construct a coarser approxim...
math/0402346
Applications of Lefschetz numbers in control theory
math.OC cs.SY math.AT
We develop some applications of techniques of the Lefschetz coincidence theory in control theory. The topics are existence of equilibria and their robustness, controllability and its robustness.
math/0403548
Remarks on codes from modular curves: MAGMA applications
math.NT cs.IT math.AG math.IT
Expository paper discussing AG or Goppa codes arising from curves, first from an abstract general perspective then turning to concrete examples associated to modular curves. We will try to explain these extremely technical ideas using a special case at a level to a typical graduate student with some background in mod...
math/0404325
Asymptotic Improvement of the Gilbert-Varshamov Bound on the Size of Binary Codes
math.CO cs.IT math.AC math.IT
Given positive integers $n$ and $d$, let $A_2(n,d)$ denote the maximum size of a binary code of length $n$ and minimum distance $d$. The well-known Gilbert-Varshamov bound asserts that $A_2(n,d) \geq 2^n/V(n,d-1)$, where $V(n,d) = \sum_{i=0}^{d} {n \choose i}$ is the volume of a Hamming sphere of radius $d$. We show ...
math/0405082
On the List and Bounded Distance Decodibility of the Reed-Solomon Codes
math.NT cs.IT math.IT
In this paper show that the list and bounded-distance decoding problems of certain bounds for the Reed-Solomon code are at least as hard as the discrete logarithm problem over finite fields.
math/0406077
A tutorial introduction to the minimum description length principle
math.ST cs.IT cs.LG math.IT stat.TH
This tutorial provides an overview of and introduction to Rissanen's Minimum Description Length (MDL) Principle. The first chapter provides a conceptual, entirely non-technical introduction to the subject. It serves as a basis for the technical introduction given in the second chapter, in which all the ideas of the f...
math/0406221
Suboptimal behaviour of Bayes and MDL in classification under misspecification
math.ST cs.IT cs.LG math.IT stat.TH
We show that forms of Bayesian and MDL inference that are often applied to classification problems can be *inconsistent*. This means there exists a learning problem such that for all amounts of data the generalization errors of the MDL classifier and the Bayes classifier relative to the Bayesian posterior both remain...
math/0408146
Learning a Machine for the Decision in a Partially Observable Markov Universe
math.GM cs.AI cs.LG
In this paper, we are interested in optimal decisions in a partially observable Markov universe. Our viewpoint departs from the dynamic programming viewpoint: we are directly approximating an optimal strategic tree depending on the observation. This approximation is made by means of a parameterized probabilistic law....
math/0409548
On mutual information, likelihood-ratios and estimation error for the additive Gaussian channel
math.PR cs.IT math.IT math.ST stat.TH
This paper considers the model of an arbitrary distributed signal x observed through an added independent white Gaussian noise w, y=x+w. New relations between the minimal mean square error of the non-causal estimator and the likelihood ratio between y and \omega are derived. This is followed by an extended version of...
math/0410317
On doubly-cyclic convolutional codes
math.RA cs.IT math.IT
Cyclicity of a convolutional code (CC) is relying on a nontrivial automorphism of the algebra F[x]/(x^n-1), where F is a finite field. If this automorphism itself has certain specific cyclicity properties one is lead to the class of doubly-cyclic CC's. Within this large class Reed-Solomon and BCH convolutional codes ...
math/0411515
Fast Non-Parametric Bayesian Inference on Infinite Trees
math.ST cs.LG math.PR stat.TH
Given i.i.d. data from an unknown distribution, we consider the problem of predicting future items. An adaptive way to estimate the probability density is to recursively subdivide the domain to an appropriate data-dependent granularity. A Bayesian would assign a data-independent prior probability to "subdivide", whic...
math/0502315
Strong Asymptotic Assertions for Discrete MDL in Regression and Classification
math.ST cs.AI cs.IT cs.LG math.IT math.PR stat.TH
We study the properties of the MDL (or maximum penalized complexity) estimator for Regression and Classification, where the underlying model class is countable. We show in particular a finite bound on the Hellinger losses under the only assumption that there is a "true" model contained in the class. This implies almo...
math/0504378
A Short Proof that Phylogenetic Tree Reconstruction by Maximum Likelihood is Hard
math.PR cs.CC cs.CE math.ST q-bio.PE stat.TH
Maximum likelihood is one of the most widely used techniques to infer evolutionary histories. Although it is thought to be intractable, a proof of its hardness has been lacking. Here, we give a short proof that computing the maximum likelihood tree is NP-hard by exploiting a connection between likelihood and parsimon...
math/0504522
On the Classification of All Self-Dual Additive Codes over GF(4) of Length up to 12
math.CO cs.IT math.IT
We consider additive codes over GF(4) that are self-dual with respect to the Hermitian trace inner product. Such codes have a well-known interpretation as quantum codes and correspond to isotropic systems. It has also been shown that these codes can be represented as graphs, and that two codes are equivalent if and o...
math/0507235
Analyticity of Entropy Rate of Hidden Markov Chains
math.PR cs.IT math.IT
We prove that under mild positivity assumptions the entropy rate of a hidden Markov chain varies analytically as a function of the underlying Markov chain parameters. A general principle to determine the domain of analyticity is stated. An example is given to estimate the radius of convergence for the entropy rate. W...
math/0508171
Matrices of Forests and the Analysis of Digraphs
math.CO cs.CV cs.NI
The matrices of spanning rooted forests are studied as a tool for analysing the structure of digraphs and measuring their characteristics. The problems of revealing the basis bicomponents, measuring vertex proximity, and ranking from preference relations / sports competitions are considered. It is shown that the vert...
math/0508319
Combinations and Mixtures of Optimal Policies in Unichain Markov Decision Processes are Optimal
math.CO cs.DM cs.LG math.OC math.PR
We show that combinations of optimal (stationary) policies in unichain Markov decision processes are optimal. That is, let M be a unichain Markov decision process with state space S, action space A and policies \pi_j^*: S -> A (1\leq j\leq n) with optimal average infinite horizon reward. Then any combination \pi of t...