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Unformatted text preview: Integer Programming IE418 Lecture 4 Dr. Ted Ralphs IE418 Lecture 4 1 Reading for This Lecture Wolsey, Chapters 8 and 9 N&W Sections I.4.1I.4.3 IE418 Lecture 4 2 Dimension of Polyhedra A polyhedron P is of dimension k , denoted dim ( P ) = k , if the maximum number of affinely independent points in P is k + 1 . A polyhedron P R n is fulldimensional if dim ( P ) = n . Let M = { 1 , . . . , m } , M = = { i M  a i x = b i x P} (the equality set ), M = M \ M = (the inequality set ). Let ( A = , b = ) , ( A , b ) be the corresponding rows of ( A, b ) . Proposition 1. If P R n , then dim ( P ) + rank ( A = , b = ) = n IE418 Lecture 4 3 Dimension and Rank x P is called an inner point of P if a i x < b i i M . x P is called an interior point of P if a i x < b i i M . Every nonempty polyhedron has an inner point . The previous proposition showed that a polyhedron has an interior point if and only if it is fulldimensional . IE418 Lecture 4 4 Computing the Dimension of a Polyhedron To compute the dimension of a polyhedron, we generally use these two equations dim ( P ) = n rank ( A = , b = ) , and dim ( P ) = max { S  : S P and the points in S are aff. indep. }  1 ....
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This note was uploaded on 08/06/2008 for the course IE 418 taught by Professor Ralphs during the Spring '08 term at Lehigh University .
 Spring '08
 Ralphs

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