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Tag Archives: optimization
Truncated BiLevel Optimization
In 2012, I wrote a paper that I probably should have called “truncated bilevel optimization”. I vaguely remembered telling the reviewers I would release some code, so I’m finally getting around to it. The idea of bilevel optimization is quite … Continue reading
Posted in Uncategorized
Tagged crossvalidation, machine learning, matlab, optimization, regularization
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Fitting an inference algorithm instead of a model
One recent trend seems to be the realization that one can get better performance by tuning a CRF (Conditional Random Field) to a particular inference algorithm. Basically, forget about the distribution that the CRF represents, and instead only care how … Continue reading
What GaussSeidel is Really Doing
I’ve been reading Alan Sokal’s lecture notes “Monte Carlo Methods in Statistical Mechanics: Foundations and New Algorithms” today. Once I learned to take the word “Hamiltonian” and mentally substitute “function to be minimized”, they are very clearly written. Anyway, the … Continue reading
HessianVector products
You have some function . You have figured out how to compute it’s gradient, . Now, however, you find that you are implementing some algorithm (like, say, Stochastic Meta Descent), and you need to compute the product of the Hessian … Continue reading
Why does regularization work?
When fitting statistical models, we usually need to “regularize” the model. The simplest example is probably linear regression. Take some training data, . Given a vector of weights , the total squared distance is So to fit the model, we … Continue reading