Thursday, November 19, 2009

God does not play dice

The title of this blog post is a famous quote by Einstein. This post is not on GOD or religion, but on the concept of probability. This post is also based on the concept of determinism and hidden variable theory.

First let's differentiate between an experiment and an event. An event simply occurs, whereas in experiment, we observe the event. Let's call this process of observing to note the outcome of the event as information retrieval process i.e we are trying to get information about the event when it occurs. Some of the information retrieval processes are seeing, hearing, or using any other sensory organs, taking a picture, video/audio recording, etc.

Note that information retrieval process may in someway disturb the event itself. See Heisenberg uncertainty principle. But for sake of this thought experiment, imagine we have some special information retrieval process that gets information about the event or experiment, without in any way disturbing the experiment. (Note, quantum mechanics says this is not possible. But I say this is not possible with currently available information retrieval mechanism. May be in future we may have sophisticated information retrieval mechanism where it might be possible).

Consider a experiment of rolling a dice. Do you think it is deterministic or probabilistic/stochastic ?

The deterministic point of view says that if we knew weight of dice, envirnomental factors (wind direction/strength, humidity), surface friction, density of dice, exact hand movements (angle of release, force during release), and many many other factors, then we can predict the exact outcome of the dice.

Since we don't know many of this factors (i.e hidden variables), we cannot predict the exact outcome of the dice. To model these variables, so that we can get very close to the outcome and in some way make the experiment useful, we use the concept of probability.

Tuesday, November 10, 2009

Presentation on Map Reduce Merge

I gave a presentation yesterday (here is the powerpoint slides) and I am writing this blog to just jot down things I have learnt.:
  1. I need to improve my grammar. The best thing to do is give a practice talk before your presentation.
  2. It is very important to add all the references in your presentation.
  3. If the paper is about a system, always add big picture describing the modules and their interactions.
  4. If possible try to prepare for a demo to get people excited about the topic.
  5. Always be sure of what you tell in the presentation. If you don't know something, say that "I don't know or I am not sure of it".
In the flow of talk, I said "As a database researcher" when I meant to say "As a database person". It seemed pompous at that time and somehow I preferred not to correct it at that time. But in retrospective as I think about it, I am a database researcher, may be not a good one and definitely not an established one. But still, I spent considerable time of my daily time doing research and I believe that qualifies me to be a "researcher".

Thursday, November 05, 2009

SACHIN TENDULKAR - The Greatest (Video Collection)

What is your motivation ?
Its the passion. I care about playing for India. Its being a dream and I am absolutely honored to do that for last 20 years. - Sachin Tendulkar.

First some of his great innings:

Second, his interviews:

Third, Documentaries:

Fourth, Best Quotes on Sachin:

And lastly, his bowling: