Author: dabacon

Posted on

Probability Intuition

Last quarter I taught discrete math. One component of the class was to cover some basic probability theory. On one of the homeworks we asked the following two questions about random five card poker hands:

  • Given that the hand contains an ace, what is the probability that the hand contains another ace?
  • Given that the hand contains the ace of diamonds, what is the probability that the hand contains another ace?

Without doing any explicit calculations, which of the above probabilities do you think will be larger?
Continue reading “Probability Intuition”

Posted on

Happy New Year! Welcome 2008!

Happy New Year! Seattle’s fireworks at the space needle had some technical difficulties (and the pyrotechnicians had to light them by hand…yeah I wrote that just to use the word “pyrotechnician”), but were still beautiful as ever:
Welcome 2008! 2008 is the international year of the potato, the international year of planet earth, and the international year of sanitation. Oh, and it is a leap year! And of further note, according to Larry Niven and Jerry Pournelle in “The Mote in God’s Eye” 2008 is the year that faster than light travel was invented. Now that should be exciting.

Posted on

Is This a Mathematica Bug?

Miguel Pais points to an interesting behavior of Mathematica, where he plots the function which is the square of the square root of x. Now, if the domain of x is taken to be complex numbers, Mathematica’s behavior seems to me to be fine. But can anyone explain this behavior
as anything other than a bug?
Update: Oops. That wasn’t the one I was trying to paste. See what happens when I disconnect from the intertubes for a few days. How about this one:

Posted on

Foxworthy Material

You know you’re in rural America when…
Reminds me of one of my favorite bumper sticker ideas of a few years ago (less true today): “Buy American: Do Meth!”

Posted on

Ski Day: Mt Shasta Ski Park

Well I finally made it to the ski slopes. Hopefully my late start to this year’s ski season will just mean that I push harder to get up to the slopes. Here is a picture taken from the base of the Mt. Shasta Ski area:
The two lifts servicing advanced terrain were shut down in the morning due to the wind, the wind chill factor was brutal, and the snow looked liked it had been shipped out directly from the East Coast: all ice and crud. But hey, it was the first day skiing!

Posted on

Merry Quantum Christmas!

Merry Christmas! I don’t think this explanation for Santa delivering presents using quantum theory works. But it does bring up the question of whether Santa could get a quadratric speedup using quantum gift delivery?