Dennis Cheung
City University of Hong Kong
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Publication
Featured researches published by Dennis Cheung.
Mathematical Programming | 2001
Dennis Cheung; Felipe Cucker
Abstract.In this paper we define a new condition number ?(A) for the following problem: given a m by n matrix A, find x∈ℝn, s.t. Ax<0. We characterize this condition number in terms of distance to ill-posedness and we compare it with existing condition numbers for the same problem.
Mathematics of Operations Research | 2003
Dennis Cheung; Felipe Cucker; Javier Peña
In recent years, several condition numbers were defined for a variety of linear programming problems based upon relative distances to ill-posedness. In this paper, we provide a unifying view of some of these condition numbers. To do so, we introduce yet another linear programming problem and show that its distance to ill-posedness naturally captures the most commonly used distances to ill-posedness.
Journal of Optimization Theory and Applications | 2002
Dennis Cheung; Felipe Cucker
In this paper, we provide bounds for the expected value of the log of the condition number C(A) of a linear feasibility problem given by a n × m matrix A (Ref. 1). We show that this expected value is O(min{n, m log n}) if n > m and is O(log n) otherwise. A similar bound applies for the log of the condition number CR(A) introduced by Renegar (Ref. 2).
Mathematical Programming | 2004
Dennis Cheung; Felipe Cucker
Abstract.We define a condition number (A,b,c) for a linear program min x s.t. Ax=b,x≥0 and give two characterizations via distances to degeneracy and singularity. We also give bounds for the expected value, as well as for higher moments, of log (A,b,c) when the entries of A,b and c are i.i.d. random variables with normal distribution.
Journal of Complexity | 2005
Dennis Cheung; Felipe Cucker
We prove that for a large class of problems, including those with a discrete set of inputs, their level-2 condition number (essentially) coincides with the original one.
Siam Journal on Optimization | 2005
Dennis Cheung; Felipe Cucker; Raphael Hauser
In this paper we study the distribution of
Handbook of Numerical Analysis | 2003
Dennis Cheung; Felipe Cucker; Yinyu Ye
\mathscr C(A)
Siam Journal on Optimization | 2008
Dennis Cheung; Felipe Cucker; Javier Peña
and
European Journal of Operational Research | 2009
Dennis Cheung; Felipe Cucker; Javier Peña
\log\mathscr C(A)
Siam Journal on Optimization | 2013
Dennis Cheung; Felipe Cucker
, where