Being a mathematician is cool again (at least for a couple of weeks).

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I was impressed that the movie used the Monty Hall problem. It's simple enough to get the point across quickly and easily. But challenges common sense.

Of course, any class of MIT seniors learning this is a huge disappointment.

Yeah, in my University (University of Amsterdam), they taught it in Stochastics 2, which is a second-year course in the Mathematics Bachelor.

It challenges common sense, but I'm surprised it confused so many people. When I first heard it, I was sceptical enough that I wrote a program to simulate it. But once it was built, there was essentially no reason to run it. Once you break the possible outcome into all the cases, it's clear what the success ratio will be just from looking at the algorithm.

The reasons it works out are subtle: (a) the host must know what's behind the doors, (b)the host must always open a door to a goat.

Most people fail to keep into account one of those assumptions. In fact most tellings of the problem fail to specify and just implicitly assume one. This leads to most confusion.

I think the telling in the movie was pretty clear though.

The assumption that generally fails to get communicated is that the host will always give you an option to switch. You can only do proper statistical analysis of the situation if know what the host will do under any given set of conditions. Otherwise you have to consider the possibility that you'll have the option of switching iff your first choice was the correct one -- in which case you obviously should never switch.

Right. I missed one.

This reminds me of Numbers, where they just throw some crazy looking math stuff on a chalkboard but never really explain it. I hope the movie is better than that!

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