## Happy Anniversary!

by

One year ago today, Batman set up this site and wrote our very first post. It was seen by approximately 3 people. At that point I had a different username, but then I saw Batman and TwoPi’s names and I got jealous and picked the Greek symbol Xi (Ξ) because in grad school someone had told me once about a class where the prof was using Ξ for some variable, and it occurred in a fraction. The top was just Ξ, but the bottom was Ξ with a bar on top. The fraction ended up looking like this:

I thought that was about the coolest fraction I’d ever seen, and I would have been Xi-over-Xi-bar if I could have, but Xi was the closest I could come.

In thinking about the posts I’ve written, my artistic abilities are rather limited (as any of my students will tell you) so I’m disproportionately proud whenever I manage to create pictures for the posts. And it’s been a surprise (not any more, but at first) how often Godzilla makes guest appearances. He’s like Charo on the Love Boat: once he jumped into the blogging world (with a photo of himself eating Buffalo-Chicken Dip) he hasn’t looked back.

Happy Anniversary 360! And since the Anniversary falls on such an auspicious day, I’ll share one of my favorite sophomore-level math jokes:

Q: Why do mathematicians think that Halloween and Christmas fall on the same day?
A: Because 31 Oct = 25 Dec.*

* Think 31 Base 8 and 25 Base 10

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### 6 Responses to “Happy Anniversary!”

1. Barry Leiba Says:

Happy annum!

The Oct/Dec joke is one I’ve always known as a computer programmer joke. Mathematicians don’t do much in Octal, really.

And the TwoPi and Xi story reminds me that two of the buildings on the Google campus in Mountain View are “Building e” and “Building π”.

2. Dave Richeson Says:

Happy anniversary!

I like the Xi-over-Xi-bar idea. There are other cool things you could do in this same vein, like Xi-over-Xi-bar equals the absolute value of negative Xi-over-Xi-bar.

3. Ξ Says:

Oh yes! Or, if it turned out that Ξ was a vector, |Ξ/|Ξ||=1 (or ||Ξ/||Ξ||||=1 if I use || instead of |).

4. Ken Rumsey Says:

Happy anniversary! I am undergrad studying pure mathematics at UCF and have just recently found your site. I am enjoying all of your past posts and looking forward to your future ones.

Ken Rumsey
Defendit numerus!

5. Ξ Says:

Thanks Ken! (I like your tagline, too 🙂 )

6. Alon Levy Says:

I heard that Barry Mazur did it once in a lecture. Serge Lang was known to interrupt lectures with “Your notation sucks!”. Mazur decided to play a prank on him: he made a T-shirt with “Your notation sucks” on it, and gave a lecture to an audience including Lang, intending to give the shirt to Lang as soon as he complained about the notation. Lang was silent, even though Mazur’s notation was deliberately bad. Eventually, Mazur said, “Let Ξ be a complex number, and consider Ξ/Ξ-bar,” drawing the shape you drew. Finally, Lang said, “Your notation sucks!”, so Mazur could give him the shirt.