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242
Factoring polynomials with rational coefficients
 MATH. ANN
, 1982
"... In this paper we present a polynomialtime algorithm to solve the following problem: given a nonzero polynomial fe Q[X] in one variable with rational coefficients, find the decomposition of f into irreducible factors in Q[X]. It is well known that this is equivalent to factoring primitive polynomia ..."
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Cited by 982 (11 self)
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In this paper we present a polynomialtime algorithm to solve the following problem: given a nonzero polynomial fe Q[X] in one variable with rational coefficients, find the decomposition of f into irreducible factors in Q[X]. It is well known that this is equivalent to factoring primitive polynomials feZ[X] into irreducible factors in Z[X]. Here we call f ~ Z[X] primitive if the greatest common divisor of its coefficients (the content of f) is 1. Our algorithm performs well in practice, cf. [8]. Its running time, measured in bit operations, is O(nl2+n9(log[fD3). Here f~Tl[X] is the polynomial to be factored, n = deg(f) is the degree of f, and for a polynomial ~ a ~ i with real coefficients a i. i An outline of the algorithm is as follows. First we find, for a suitable small prime number p, a padic irreducible factor h of f, to a certain precision. This is done with Berlekamp's algorithm for factoring polynomials over small finite fields, combined with Hensel's lemma. Next we look for the irreducible factor h o of f in
Closest Point Search in Lattices
 IEEE TRANS. INFORM. THEORY
, 2000
"... In this semitutorial paper, a comprehensive survey of closestpoint search methods for lattices without a regular structure is presented. The existing search strategies are described in a unified framework, and differences between them are elucidated. An efficient closestpoint search algorithm, ba ..."
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Cited by 324 (2 self)
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In this semitutorial paper, a comprehensive survey of closestpoint search methods for lattices without a regular structure is presented. The existing search strategies are described in a unified framework, and differences between them are elucidated. An efficient closestpoint search algorithm, based on the SchnorrEuchner variation of the Pohst method, is implemented. Given an arbitrary point x 2 R m and a generator matrix for a lattice , the algorithm computes the point of that is closest to x. The algorithm is shown to be substantially faster than other known methods, by means of a theoretical comparison with the Kannan algorithm and an experimental comparison with the Pohst algorithm and its variants, such as the recent ViterboBoutros decoder. The improvement increases with the dimension of the lattice. Modifications of the algorithm are developed to solve a number of related search problems for lattices, such as finding a shortest vector, determining the kissing number, compu...
A Singular Loop Transformation Framework Based on Nonsingular Matrices
, 1992
"... In this paper, we discuss a loop transformation framework that is based on integer nonsingular matrices. The transformations included in this framework are called transformations and include permutation, skewing and reversal, as well as a transformation called loop scaling. This framework is mo ..."
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Cited by 131 (8 self)
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In this paper, we discuss a loop transformation framework that is based on integer nonsingular matrices. The transformations included in this framework are called transformations and include permutation, skewing and reversal, as well as a transformation called loop scaling. This framework is more general than existing ones; however, it is also more difficult to generate code in our framework. This paper shows how integer lattice theory can be used to generate efficient code. An added advantage of our framework over existing ones is that there is a simple completion algorithm which, given a partial transformation matrix, produces a full transformation matrix that satisfies all dependences. This completion procedure has applications in parallelization and in the generation of code for NUMA machines.
Averaging bounds for lattices and linear codes
 IEEE Trans. Information Theory
, 1997
"... Abstract — General random coding theorems for lattices are derived from the Minkowski–Hlawka theorem and their close relation to standard averaging arguments for linear codes over finite fields is pointed out. A new version of the Minkowski–Hlawka theorem itself is obtained as the limit, for p!1,ofa ..."
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Cited by 97 (1 self)
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Abstract — General random coding theorems for lattices are derived from the Minkowski–Hlawka theorem and their close relation to standard averaging arguments for linear codes over finite fields is pointed out. A new version of the Minkowski–Hlawka theorem itself is obtained as the limit, for p!1,ofasimple lemma for linear codes over GF (p) used with plevel amplitude modulation. The relation between the combinatorial packing of solid bodies and the informationtheoretic “soft packing ” with arbitrarily small, but positive, overlap is illuminated. The “softpacking” results are new. When specialized to the additive white Gaussian noise channel, they reduce to (a version of) the de Buda–Poltyrev result that spherically shaped lattice codes and adecoder that is unaware of the shaping can achieve the rate 1=2 log2 (P=N).
Computing Minimum Length Paths of a Given Homotopy Class
 Comput. Geom. Theory Appl
, 1991
"... In this paper, we show that the universal covering space of a surface can be used to unify previous results on computing paths in a simple polygon. We optimize a given path among obstacles in the plane under the Euclidean and link metrics and under polygonal convex distance functions. Besides reveal ..."
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Cited by 93 (6 self)
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In this paper, we show that the universal covering space of a surface can be used to unify previous results on computing paths in a simple polygon. We optimize a given path among obstacles in the plane under the Euclidean and link metrics and under polygonal convex distance functions. Besides revealing connections between the minimum paths under these three distance functions, the framework provided by the universal cover leads to simplified lineartime algorithms for shortest path trees, for minimumlink paths in simple polygons, and for paths restricted to c given orientations. 1 Introduction If a wire, a pipe, or a robot must traverse a path among obstacles in the plane, then one might ask what is the best route to take. For the wire, perhaps the shortest distance is best; for the pipe, perhaps the fewest straightline segments. For the robot, either might be best depending on the relative costs of turning and moving. In this paper, we find shortest paths and shortest closed curve...
Solving simultaneous modular equations of low degree
 SIAM J. of Computing
, 1988
"... Abstract: We consider the problem of solving systems of equations Pi(x) 0 (mod ni) i = 1:::k where Pi are polynomials of degree d and the ni are distinct relatively prime numbers and x < min(ni). We prove that if k> d(d+1) we can recover x in polynomial 2 time provided min(ni)> 2d2. As a co ..."
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Cited by 84 (0 self)
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Abstract: We consider the problem of solving systems of equations Pi(x) 0 (mod ni) i = 1:::k where Pi are polynomials of degree d and the ni are distinct relatively prime numbers and x < min(ni). We prove that if k> d(d+1) we can recover x in polynomial 2 time provided min(ni)> 2d2. As a consequence the RSA cryptosystem used with a small exponent is not a good choice to use as a public key cryptosystem in a large network. We also show that a protocol by Broder and Dolev [4] is insecure if RSA with a small exponent is used. Warning: Essentially this paper has been published in SIAM Journal on Computing and is hence subject to copyright restrictions. It is for personal use only. 1.
On quaternions and octonions: their geometry, arithmetic, and symmetry, A K
, 2003
"... Conway and Smith’s book is a wonderful introduction to the normed division algebras: the real numbers (R), the complex numbers (C), the quaternions (H), and the octonions (O). The first two are wellknown to every mathematician. In contrast, the quaternions and especially the octonions are sadly neg ..."
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Cited by 79 (0 self)
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Conway and Smith’s book is a wonderful introduction to the normed division algebras: the real numbers (R), the complex numbers (C), the quaternions (H), and the octonions (O). The first two are wellknown to every mathematician. In contrast, the quaternions and especially the octonions are sadly neglected, so the authors rightly concentrate on these. They develop these number systems from scratch, explore their connections to geometry, and even study number theory in quaternionic and octonionic versions of the integers. Conway and Smith warm up by studying two famous subrings of C: the Gaussian integers and Eisenstein integers. The Gaussian integers are the complex numbers x + iy for which x and y are integers. They form a square lattice:
On the singularity probability of random Bernoulli matrices, to appear
 Soc Department of Mathematics, UCSD, La Jolla, CA 92093 Email address: kcostell@ucsd.edu Department of Mathematics, Rutgers, Piscataway, NJ 08854 Email address: vanvu@math.rutgers.edu
"... Abstract. Let n be a large integer and Mn be a random n by n matrix whose entries are i.i.d. Bernoulli random variables (each entry is±1 with probability 1/2). We show that the probability that Mn is singular is at most (3/4+o(1)) n, improving an earlier estimate of Kahn, Komlós and Szemerédi [11], ..."
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Cited by 63 (18 self)
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Abstract. Let n be a large integer and Mn be a random n by n matrix whose entries are i.i.d. Bernoulli random variables (each entry is±1 with probability 1/2). We show that the probability that Mn is singular is at most (3/4+o(1)) n, improving an earlier estimate of Kahn, Komlós and Szemerédi [11], as well as earlier work by the authors [17]. The key new ingredient is the applications of Freiman type inverse theorems and other tools from additive combinatorics. 1.
A Deterministic Single Exponential Time Algorithm for Most Lattice Problems based on Voronoi Cell Computations (Extended Abstract)
, 2009
"... We give deterministic 2O(n)time algorithms to solve all the most important computational problems on point lattices in NP, including the Shortest Vector Problem (SVP), Closest Vector Problem (CVP), and Shortest Independent Vectors Problem (SIVP). This improves the nO(n) running time of the best pre ..."
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Cited by 62 (3 self)
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We give deterministic 2O(n)time algorithms to solve all the most important computational problems on point lattices in NP, including the Shortest Vector Problem (SVP), Closest Vector Problem (CVP), and Shortest Independent Vectors Problem (SIVP). This improves the nO(n) running time of the best previously known algorithms for CVP (Kannan, Math. Operation Research 12(3):415440, 1987) and SIVP (Micciancio, Proc. of SODA, 2008), and gives a deterministic alternative to the 2 O(n)time (and space) randomized algorithm for SVP of (Ajtai, Kumar and Sivakumar, STOC 2001). The core of our algorithm is a new method to solve the closest vector problem with preprocessing (CVPP) that uses the Voronoi cell of the lattice (described as intersection of halfspaces) as the result of the preprocessing function. In the process, we also give algorithms for several other lattice problems, including computing the kissing number of a lattice, and computing the set of all Voronoi relevant vectors. All our algorithms are deterministic, and have 2 O(n) time and space complexity 1 1