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38
Submodular functions, matroids and certain polyhedra
, 2003
"... The viewpoint of the subject of matroids, and related areas of lattice theory, has always been, in one way or another, abstraction of algebraic dependence or, equivalently, abstraction of the incidence relations in geometric representations of algebra. Often one of the main derived facts is that all ..."
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The viewpoint of the subject of matroids, and related areas of lattice theory, has always been, in one way or another, abstraction of algebraic dependence or, equivalently, abstraction of the incidence relations in geometric representations of algebra. Often one of the main derived facts is that all bases have the same cardinality. (See Van der Waerden, Section 33.) From the viewpoint of mathematical programming, the equal cardinality of all bases has special meaning — namely, that every basis is an optimumcardinality basis. We are thus prompted to study this simple property in the context of linear programming. It turns out to be useful to regard “pure matroid theory”, which is only incidentally related to the aspects of algebra which it abstracts, as the study of certain classes of convex polyhedra. (1) A matroid M = (E,F) can be defined as a finite set E and a nonempty family F of socalled independent subsets of E such that (a) Every subset of an independent set is independent, and (b) For every A ⊆ E, every maximal independent subset of A, i.e., every basis of A, has the same cardinality, called the rank, r(A), of A (with respect to M). (This definition is not standard. It is prompted by the present interest). (2) Let RE denote the space of realvalued vectors x = [xj], j ∈ E. Let R+E = {x: 0 ≤ x ∈ RE}. (3) A polymatroid P in the space RE is a compact nonempty subset of R+E such that (a) 0 ≤ x0 ≤ x1 ∈ P = ⇒ x0 ∈ P. (b) For every a ∈ R+E, every maximal x ∈ P such that x ≤ a, i.e., every basis x of a, has the same sum j∈E xj, called the rank, r(a), of a (with respect to P).
A PrimalDual Interior Point Method Whose Running Time Depends Only on the Constraint Matrix
, 1995
"... We propose a primaldual "layeredstep " interior point (LIP) algorithm for linear programming with data given by real numbers. This algorithm follows the central path, either with short steps or with a new type of step called a "layered least squares " (LLS) ste ..."
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Cited by 58 (8 self)
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We propose a primaldual &quot;layeredstep &quot; interior point (LIP) algorithm for linear programming with data given by real numbers. This algorithm follows the central path, either with short steps or with a new type of step called a &quot;layered least squares &quot; (LLS) step. The algorithm returns an exact optimum after a finite number of stepsin particular, after O(n3:5c(A)) iterations, where c(A) is a function of the
Fast parallel matrix and GCD computations
 IN PROC. OF THE 23RD ANNUAL SYMPOSIUM ON FOUNDATIONS OF COMPUTER SCIENCE (FOCS’82
, 1982
"... Parallel algorithms to compute the determinant and characteristic polynomial of matrices and the gcd of polynomials are presented. The rank of matrices and solutions of arbitrary systems of linear equations are computed by parallel Las Vegas algorithms. All algorithms work over arbitrary fields. The ..."
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Cited by 48 (1 self)
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Parallel algorithms to compute the determinant and characteristic polynomial of matrices and the gcd of polynomials are presented. The rank of matrices and solutions of arbitrary systems of linear equations are computed by parallel Las Vegas algorithms. All algorithms work over arbitrary fields. They run in parallel time O(log ~ n) (where n is the number of inputs) and use a polynomial number of processors.
The optimal pathmatching problem
 COMBINATORICA
, 1997
"... We describe a common generalization of the weighted matching problem and the weighted matroid intersection problem. In this context we establish common generalizations of the main results on those two problemspolynomialtime solvability, minmax theorems, and totally dual integral polyhedral descr ..."
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Cited by 25 (2 self)
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We describe a common generalization of the weighted matching problem and the weighted matroid intersection problem. In this context we establish common generalizations of the main results on those two problemspolynomialtime solvability, minmax theorems, and totally dual integral polyhedral descriptions. New applications of these results include a strongly polynomial separation algorithm for the convex hull of matchable sets of a graph, and a polynomialtime algorithm to compute the rank of a certain matrix of indeterminates.
Random PseudoPolynomial Algorithms for Exact Matroid Problems
, 1992
"... In this work we present a random pseudopolynomial algorithm for the problem of finding a base of specified value in a weighted represented matroid, subject to parity conditions. We also describe a specialized version of the algorithm suitable for finding a base of specified value in the intersectio ..."
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Cited by 21 (0 self)
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In this work we present a random pseudopolynomial algorithm for the problem of finding a base of specified value in a weighted represented matroid, subject to parity conditions. We also describe a specialized version of the algorithm suitable for finding a base of specified value in the intersection of two matroids. This result generalizes an existing pseudopolynomial algorithm for computing exact arborescences in weighted graphs. Another (simpler) specialized version of our algorithms is also presented for computing perfect matchings of specified value in weighted graphs.
Computing the sign or the value of the determinant of an integer matrix, a complexity survey
 JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS
, 2004
"... Computation of the sign of the determ9vSof amWDz[ and the determBvSitself is a challenge for both numhvB5q and exact mactv;W We survey the comWzqDvS of existingmistin to solve these problem when the input is an nnm;9q; A with integer entries. We study the bitcomvSW5[5Wv of the algorithm asymithmW5[ ..."
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Cited by 19 (3 self)
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Computation of the sign of the determ9vSof amWDz[ and the determBvSitself is a challenge for both numhvB5q and exact mactv;W We survey the comWzqDvS of existingmistin to solve these problem when the input is an nnm;9q; A with integer entries. We study the bitcomvSW5[5Wv of the algorithm asymithmW5[5 n and thenorm of A. Existing approaches rely onnumBDWzv approximW[ comoximW[z5 on exactcomvB[;5vSW or on both types of arithmvSW incom9zqvSWqD c 2003 Elsevier B.V. All rights reserved. Keywords: Determ9v9vm Bitcom9vmv Integer mteger Approxim59 comoxim599 Exact comv55DvS Random5D algorithm 1. I517251716 Com;vm9 the sign or the value of thedetermDvS; nmBqq A is a classicalproblem Numblem mmble are usually focused oncomBW9v the sign via an accurateapproxim;B99 of the determvS;;5 Amer the applications areimvWD;qW problem ofcom9qWvS;;5[ geom9qW that can be reduced to the determ5vS; question; the readerma refer to [11,12,9,10,46,45] and to the bibliography therein. InsymDW;B comW;BvS55 theproblem ofcomDzWv the exact value of the ThismisvqB; is based on work supported in part by the National Science Foundation under grants Nrs. DMS9977392, CCR9988177, and CCR0113121 (Kaltofen) and by the Centre National de la Recherche Scienti#que, Actions Incitatives No. 5929 et STIC LINBOX 2001 (Villard).
An Accelerated Interior Point Method Whose Running Time Depends Only on A
 IN PROCEEDINGS OF 26TH ANNUAL ACM SYMPOSIUM ON THE THEORY OF COMPUTING
, 1993
"... We propose a "layeredstep" interior point (LIP) algorithm for linear programming. This algorithm follows the central path, either with short steps or with a new type of step called a "layered least squares" (LLS) step. The algorithm returns the exact global minimum after a finit ..."
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Cited by 16 (2 self)
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We propose a "layeredstep" interior point (LIP) algorithm for linear programming. This algorithm follows the central path, either with short steps or with a new type of step called a "layered least squares" (LLS) step. The algorithm returns the exact global minimum after a finite number of stepsin particular, after O(n 3:5 c(A)) iterations, where c(A) is a function of the coefficient matrix. The LLS steps can be thought of as accelerating a pathfollowing interior point method whenever neardegeneracies occur. One consequence of the new method is a new characterization of the central path: we show that it composed of at most n 2 alternating straight and curved