MIT 6.854 Spring 2016 Lecture 12: From Separation to Optimization and Back; Ellipsoid Method

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Recorded by Andrew Xia
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00:00 - 18:20 setup for ellipsoid method
18:20 - 25:20 ellipsoid method idea and definition of ellipsoid
25:20 - 35:00 ellipsoid algorithm
35:00 finding ellipsoid in (k+1)th iteration
43:30 - 49:57 claim 1 and proof
49:57 - 54:50 claim 2 and proof
55:15 - 1:11:15 general case E(a, A)
1:11:15 - 1:18:00 reduction from feasibility to optimization

aleksagordic
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Great lecturer - this is a nice primer before reading the paper by Grötschel, Lovász, and Schrijver.

J-gv
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For the guys out there trying to learn ellipsoid method, it being historically the first polytime method for solving LPs, let me point out a little tricky detail.
The lecturer proposes reducing optimization to feasibility via the joint feasibility LP. That seems pretty slick at first, but remember, that in the generic case, the joint feasibility LP will have a zero-dimensional polytope made of a single point (x*, y*). Do you know what happens to ellipsoid method when your polytope is zero-dimensional?

nkt
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The statement of the ellipsoid algorithm starts at 20:00

starklitho