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Published byLucinda Howard Modified over 9 years ago
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Convex Optimization Chapter 1 Introduction
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What, Why and How What is convex optimization Why study convex optimization How to study convex optimization
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What is Convex Optimization?
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Mathematical Optimization Convex Optimization Least-squaresLP Nonlinear Optimization
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Mathematical Optimization
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Convex Optimization
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Least-squares
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Analytical Solution of Least-squares f 0 ( x ) = jj A x ¡ b jj 2 2 = ( A x ¡ b ) > ( A x ¡ b ) x = ( A > A ) ¡ 1 A > b @f 0 ( x ) @ x = 2 A > ( A x ¡ b ) = 0
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Linear Programming (LP)
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Why Study Convex Optimization?
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Mathematical Optimization Convex Optimization Least-squaresLP Solving Optimization Problems Nonlinear Optimization
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Analytical solution Good algorithms and software High accuracy and high reliability Time complexity: Mathematical Optimization Convex Optimization Least-squares LP Nonlinear Optimization A mature technology!
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No analytical solution Algorithms and software Reliable and efficient Time complexity: Mathematical Optimization Convex Optimization Least-squares LP Nonlinear Optimization Also a mature technology!
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Mathematical Optimization Convex Optimization Nonlinear Optimization Almost a mature technology! Least-squares LP No analytical solution Algorithms and software Reliable and efficient Time complexity (roughly)
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Mathematical Optimization Convex Optimization Nonlinear Optimization Far from a technology! (something to avoid) Least-squares LP Sadly, no effective methods to solve Only approaches with some compromise Local optimization: “more art than technology” Global optimization: greatly compromised efficiency Help from convex optimization 1) Initialization 2) Heuristics 3) Bounds
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Why Study Convex Optimization If not, …… -- Section 1.3.2, p8, Convex Optimization there is little chance you can solve it.
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How to Study Convex Optimization?
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Two Directions As potential users of convex optimization As researchers developing convex programming algorithms
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Recognizing least-squares problems Straightforward: verify the objective to be a quadratic function the quadratic form is positive semidefinite Standard techniques increase flexibility Weighted least-squares Regularized least-squares
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Recognizing LP problems Example: Sum of residuals approximation Chebyshev or minimax approximation t = max i j a > i x ¡ b i j t i = j r i j
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Recognizing Convex Optimization Problems
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An Example
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8 f j 1 ; j 2 ; ¢¢¢ ; j 10 g P 10 k = 1 p j k · 1 2 P m j = 1 p j Adding linear constraints????? C 10 m
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Summary From the book, we expect to learn To recognize convex optimization problems To formulate convex optimization problems To (know what can) solve them!
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