Results 1  10
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38
Algebraic Algorithms for Sampling from Conditional Distributions
 Annals of Statistics
, 1995
"... We construct Markov chain algorithms for sampling from discrete exponential families conditional on a sufficient statistic. Examples include generating tables with fixed row and column sums and higher dimensional analogs. The algorithms involve finding bases for associated polynomial ideals and so a ..."
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Cited by 192 (16 self)
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We construct Markov chain algorithms for sampling from discrete exponential families conditional on a sufficient statistic. Examples include generating tables with fixed row and column sums and higher dimensional analogs. The algorithms involve finding bases for associated polynomial ideals and so an excursion into computational algebraic geometry.
Gröbner Bases of Lattices, Corner Polyhedra, and Integer Programming
, 1995
"... There are very close connections between the arithmetic of integer lattices, algebraic properties of the associated ideals, and the geometry and the combinatorics of corresponding polyhedra. In this paper we investigate the generating sets ("Gröbner bases") of integer lattices that correspond to the ..."
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Cited by 28 (6 self)
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There are very close connections between the arithmetic of integer lattices, algebraic properties of the associated ideals, and the geometry and the combinatorics of corresponding polyhedra. In this paper we investigate the generating sets ("Gröbner bases") of integer lattices that correspond to the Gröbner bases of the associated binomial ideals. Extending results by Sturmfels & Thomas, we obtain a geometric characterization of the universal Gröbner basis in terms of the vertices and edges of the associated corner polyhedra. In the special case where the lattice has finite index, the corner polyhedra were studied by Gomory, and there is a close connection to the "group problem in integer programming." We present exponential lower and upper bounds for the maximal size of a reduced Grobner basis. The initial complex of (the ideal of) a lattice is shown to be dual to the boundary of a certain simple polyhedron.
"One sugar cube, please" or Selection strategies in the Buchberger algorithm
 Proceedings of the ISSAC'91, ACM Press
, 1991
"... In this paper we describe some experimental findings on selection strategies for Gröbner basis computation with the Buchberger algorithm. In particular, the results suggest that the "sugar flavor" of the "normal selection", implemented first in CoCoA, then in AlPI, and now in SCRATCHPADII, is the b ..."
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Cited by 25 (2 self)
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In this paper we describe some experimental findings on selection strategies for Gröbner basis computation with the Buchberger algorithm. In particular, the results suggest that the "sugar flavor" of the "normal selection", implemented first in CoCoA, then in AlPI, and now in SCRATCHPADII, is the best choice for a selection strategy. It has to be combined with the "straightforward" simplification strategy and with a special form of the GebauerMöller criteria to obtain the best results. The idea of the "sugar flavor" is the following: the Buchberger algorithm for homogeneous ideals, with degreecompatible term ordering and normal selection strategy, usually works fine. Homogenizing the basis of the ideal is good for the strategy, but bad for the basis to be computed. The sugar flavor computes, for every polynomial in the course of the algorithm, "the degree that it would have if computed with the homogeneous algorithm", and uses this phantom degree (the sugar) only for the selection strategy. We have tested several examples with different selection strategies, and the sugar flavor has proved to be always the best choice or very near to it. The comparison between the different variants of the sugar flavor has been made, but the results are up to now inconclusive. We include a complete deterministic description of the Buchberger algorithm as it was used in our experiments.
Gomory Integer Programs
, 2001
"... The set of all group relaxations of an integer program contains certain special members called Gomory relaxations. A family of integer programs with a fixed coefficient matrix and cost vector but varying right hand sides is a Gomory family if every program in the family can be solved by one of its G ..."
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Cited by 24 (3 self)
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The set of all group relaxations of an integer program contains certain special members called Gomory relaxations. A family of integer programs with a fixed coefficient matrix and cost vector but varying right hand sides is a Gomory family if every program in the family can be solved by one of its Gomory relaxations. In this paper, we characterize Gomory families. Every TDI system gives a Gomory family, and we construct Gomory families from matrices whose columns form a Hilbert basis for the cone they generate. The existence of Gomory families is related to the Hilbert covering problems that arose from the conjectures of Sebö. Connections to commutative algebra are outlined at the end.
NonStandard Approaches to Integer Programming
, 2000
"... In this survey we address three of the principle algebraic approaches to integer programming. After introducing... ..."
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Cited by 22 (4 self)
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In this survey we address three of the principle algebraic approaches to integer programming. After introducing...
Sequential importance sampling for multiway tables
 Annals of Statistics
, 2005
"... We describe an algorithm for the sequential sampling of entries in multiway contingency tables with given constraints. The algorithm can be used for computations in exact conditional inference. To justify the algorithm, a theory relates sampling values at each step to properties of the associated to ..."
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Cited by 21 (3 self)
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We describe an algorithm for the sequential sampling of entries in multiway contingency tables with given constraints. The algorithm can be used for computations in exact conditional inference. To justify the algorithm, a theory relates sampling values at each step to properties of the associated toric ideal using computational commutative algebra. In particular, the property of interval cell counts at each step is related to exponents on lead indeterminates of a lexicographic Gröbner basis. Also, the approximation of integer programming by linear programming for sampling is related to initial terms of a toric ideal. We apply the algorithm to examples of contingency tables which appear in the social and medical sciences. The numerical results demonstrate that the theory is applicable and that the algorithm performs well. 1. Introduction. Sampling
Identification of Faces in a 2D Line Drawing Projection of a Wireframe Object
 IEEE Transactions on Pattern Analysis and Machine Intelligence
, 1996
"... An important key to reconstructing a threedimensional object depicted by a twodimensional line drawing projection is face identification. Identification of edge circuits in a 2D projection corresponding to actual faces of a 3D object becomes complex when the projected object is in wireframe rep ..."
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Cited by 20 (5 self)
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An important key to reconstructing a threedimensional object depicted by a twodimensional line drawing projection is face identification. Identification of edge circuits in a 2D projection corresponding to actual faces of a 3D object becomes complex when the projected object is in wireframe representation. This representation is commonly encountered in drawings made during the conceptual design stage of mechanical parts. When nonmanifold objects are considered, the situation becomes even more complex. This paper discusses the principles underlying face identification and presents an algorithm capable of performing this identification. Faceedgevertex relationships applicable to nonmanifold objects are also proposed. Examples from a working implementation are given. Index Terms  Line drawing interpretation, face identification, line labeling, 3D object reconstruction, nonmanifold geometry, image understanding. 1.
StrategyAccurate Parallel Buchberger Algorithms
, 1996
"... this paper we describe two parallel formulations of Buchberger algorithm, one for y ..."
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Cited by 13 (0 self)
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this paper we describe two parallel formulations of Buchberger algorithm, one for y
A Primal AllInteger Algorithm Based on Irreducible Solutions
, 2001
"... This paper introduces an exact primal augmentation algorithm for solving general linear integer programs. The algorithm iteratively substitutes one column in a tableau by other columns that correspond to irreducible solutions of certain linear diophantine inequalities. We prove that various versions ..."
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Cited by 11 (5 self)
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This paper introduces an exact primal augmentation algorithm for solving general linear integer programs. The algorithm iteratively substitutes one column in a tableau by other columns that correspond to irreducible solutions of certain linear diophantine inequalities. We prove that various versions of our algorithm are finite. It is a major concern in this paper to show how the subproblem of replacing a column can be accomplished effectively. An implementation of the presented algorithms is given. Computational results for a number of hard 0/1 integer programs from the MIPLIB demonstrate the practical power of the method.