Machine Learning (Theory)

7/18/2010

ICML & COLT 2010

The papers which interested me most at ICML and COLT 2010 were:

  1. Thomas Walsh, Kaushik Subramanian, Michael Littman and Carlos Diuk Generalizing Apprenticeship Learning across Hypothesis Classes. This paper formalizes and provides algorithms with guarantees for mixed-mode apprenticeship and traditional reinforcement learning algorithms, allowing RL algorithms that perform better than for either setting alone.
  2. István Szita and Csaba Szepesvári Model-based reinforcement learning with nearly tight exploration complexity bounds. This paper and anotherrepresent the frontier of best-known algorithm for Reinforcement Learning in a Markov Decision Process.
  3. James Martens Deep learning via Hessian-free optimization. About a new not-quite-online second order gradient algorithm for learning deep functional structures. Potentially this is very powerful because while people have often talked about end-to-end learning, it has rarely worked in practice.
  4. Chrisoph Sawade, Niels Landwehr, Steffen Bickel. and Tobias Scheffer Active Risk Estimation. When a test set is not known in advance, the model can be used to safely aid test set evaluation using importance weighting techniques. Relative to the paper, placing a lower bound on p(y|x) is probably important in practice.
  5. H. Brendan McMahan and Matthew Streeter Adaptive Bound Optimization for Online Convex Optimization and the almost-same paper John Duchi, Elad Hazan, and Yoram Singer, Adaptive Subgradient Methods for Online Learning and Stochastic Optimization. These papers provide tractable online algorithms with regret guarantees over a family of metrics rather than just euclidean metrics. They look pretty useful in practice.
  6. Nicolò Cesa-Bianchi, Claudio Gentile, Fabio Vitale, Giovanni Zappella, Active Learning on Trees and Graphs Various subsets of these authors have other papers about actively learning graph-obeying functions which in total provide a good basis for understanding what’s possible and how to learn.

The program chairs for ICML did a wide-ranging survey over participants. The results seem to suggest that participants generally agree with the current ICML process. I expect there is some amount of anchoring effect going on where participants have an apparent preference for the known status quo, although it’s difficult to judge the degree of that. Some survey results which aren’t of that sort are:

  1. 7.7% of reviewers say author feedback changed their mind. It would be interesting to know for which fraction of accepted papers reviewers had their mind changed, but that isn’t there.
  2. 85.4% of authors don’t know if the reviewers read their response, believe they read and ignored it, or believe they didn’t read it. Authors clearly don’t feel like they are communicating with reviewers.
  3. 58.6% support growing the conference with the largest fraction suggesting poster-only papers.
  4. Other conferences attended by the ICML community in order are NIPS, ECML/PKDD, AAAI, IJCAI, AIStats, UAI, KDD, ICDM, COLT, SIGIR, ECAI, EMNLP, CoNLL. This is pretty different from the standard colocation list for ICML. Many possibilities are precluded by scheduling, but AAAI, IJCAI, UAI, KDD, COLT, SIGIR are all serious possibilities some of which haven’t been used much in the past.

My experience with Mark‘s new paper discussion site is generally positive—having comments emailed to interested parties really helps the discussion. There are a few comments that authors haven’t responded to, so if you are an author you might want to sign up to receive comments.

In addition, I was the workshop chair for ICML&COLT this year. My overall impression was that things went reasonably well, with the exception of internet connectivity at Dan Panorama which was a minidisaster courtesy of a broken per-machine authentication system. One of the things I’m particularly happy about was the Learning to Rank Challenge workshop. I think it would be great if ICML can continue to attract new challenge workshops in the future. If anyone else has comments about the workshops, I’d love to hear them.

7/2/2010

MetaOptimize

Tags: Announcements,Machine Learning jl@ 12:39 am

Joseph Turian creates MetaOptimize for discussion of NLP and ML on big datasets. This includes a blog, but perhaps more importantly a question and answer section. I’m hopeful it will take off.

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