Ravi Mohan's Tech Blog. To read my non technical blog, click here

Tuesday, March 24, 2009

Ada Lovelace Day: Daphne Koller

Via Sunayana's Blog I came to know about the Ada Lovelace Day pledge whereby people write about women in computing they admire.

Now, I am personally not convinced there is a real crisis surrounding a "lack of women in computing". My attitude towards "women in computing" is expressed perfectly in George RR Martin's Novel "A Game of Thrones" by Syrio Forel, The First Sword of Bravos, when he is teaching Arya Stark, who is a very atypical girl, - given the medival setting of the story - and a bit of a tomboy, the finer points of sword fighting. He calls her "boy" a few too many times till she gets irritated and says "But I am a girl" And Syrio replies , "Boy, Girl you are a sword". Likewise for me, in computing , "Boy, Girl, you are a mind" I could care less about a person's chromosomal makeup.

That said , let me talk about a mind I admire, which happens to reside in a woman' body. :-)

Daphne Koller is a professor at Stanford whose research is about applying probabilistic techniques to complex domains. I've never met her (I should be lucky enough to study in Stanford!) but I've exchanged a few emails with her.

I was coding up a robotics algorithm and the paper elucidating the algorithm had a reference to one of her papers, "Using learning for approximation in stochastic processes". This paper explained a brilliant, elegant idea - in essence, instead of, in a particle filter (say) generating the t+ 1'th generation of particles from the t'th generation, the idea is to (a) create a probability distribution pd from the t'th generation and (b) sample from pd to get the t+1th generation.

Unfortunately there wasn't enough information in the paper to code up a density tree , so I wrote to Dr Koller asking her if she had some code available. She didn't, (the code was lost a long time ago!) but she very graciously supplied me with enough detail so I could figure out the data structure myself and successfully complete my coding effort.

Dr Koller's papers are a treasure trove for anyone interested in her research areas and she is tremendously admired within the research community.Very few people combine brilliance and grace. Dr Koller is one of them. She is a great role model for anyone in computing (irrespective of chromosmal make up) to look up to and learn from

Sunday, March 22, 2009

GnuPlot In Action

is a great (e)book. I got the early access version from Manning and it is very well written. Phillip Jaanert has done a great job. I've been using it to visualize the output of some algorithms I've been coding up.

here is a graph I created with GnuPlot for the optimal decisions for different learning rates for 2000 one armed bandits (essentially a stateless value function less precursor to Reinforcement Learning)