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Tales of Statisticians: George B. Dantzig

34 pointsby KhalilKover 10 years ago

2 comments

idunningover 10 years ago
Simplex method was a game changer.<p>Its a funny algorithm: worst-case time complexity is exponential in the input size, and is pretty easy to demonstrate (see &quot;Klee-Minty cube&quot; on Wikipedia). It has a couple of &quot;rules&quot; you can change out that will fix the exponential problem for some cases, only to introduce new problematic cases elsewhere. However the reality is that it demonstrates polynomial-like performance on almost all problems of interest, and that is why it is so widely used.<p>Later, interior point methods arose that can be faster sometimes (and are polynomial time complexity), but they didn&#x27;t kill the simplex method. This is partly due to one key property of the simplex method: at optimality, you can change the linear program in many different small ways and start the algorithm again from where you left off (sometimes you need the dual simplex method, a sibling method). You&#x27;ll return to feasible optimality in usually only a few iterations. This is what powers the branch-and-bound approach to integer programming, which is the really useful application of LP these days. Interior point methods don&#x27;t really have good warm starts to this day, certainly not good enough for branch-and-bound.<p>I&#x27;ve met several professors who kinda don&#x27;t like the simplex method because (they say) it is not a beautiful algorithm from a theory perspective, but I think its wonderful.<p>Oh, and PSA: very difficult to implement correctly! The textbook algorithm will fail terribly on real problems due to floating point issues - please use an existing implementation if you need to solve LPs!
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paperworkover 10 years ago
&quot;The Lady Tasting Tea&quot;[1] is a fantastic book about statisticians. Someone recommended that book to me as an intro to stats, which it most certainly is not. However, if you have had even a single course in statistics, you will recognize many of the names and learn how they influenced the modern era.<p>Frankly, I wish the author had devoted a couple of pages at the end of each chapter to delve deeper into the technical concepts. Nonetheless, the book makes an interesting read, even for non-statisticians.<p>[1]<a href="http://www.amazon.com/The-Lady-Tasting-Tea-Revolutionized/dp/0805071342" rel="nofollow">http:&#x2F;&#x2F;www.amazon.com&#x2F;The-Lady-Tasting-Tea-Revolutionized&#x2F;dp...</a>