## Archive for September, 2008

### Here Be Dragons

$\bullet$Brent’s decimal expansion zoo.

$\bullet$Le Carnaval des Mathématiques, #40, chez Staring At Empty Pages.
$\bullet$Photos from the Cathleen Morawetz festschrift, by the Accidental.

### Wheee!

I’ve met each class twice with no major snafus.

I didn’t have the book for 130 until after class yesterday so I did the “Linear Inequalites” section (1.2) before the “Applications of Equations” (1.1)—it’s a whole lot easier making up inequalities off the top of my head (that’re essentially the same as the exercises) than it’d be to make up “applications” (i.e., word problems). Now that I’ve got the book, I discover that there’s a boxed-off “definition” to this effect.

An inequality is a statement that one number is less than another number.
This isn’t just wrong or even just obviously wrong: the silly son-of-a-bitches know it’s wrong: the line before this box says “The next definition is stated in terms of the less-than relation (<), but it applies also to the other relations (>, ≤, ≥).”.

How is this anything but worse-than-useless to anyone? I’m more or less convinced as of right now that I’d’ve given a worse lecture yesterday if I had’ve had the book—I’d very likely have felt obliged to do some version of this rant right there and students are already pretty weirded-out on the first day of class without the instructor going off on some random angry tirade.

It may be even more to the point to mention that the “Rules for Inequalities” that follow could hardly be presented in a more confusing style: the heart of the matter (“change direction when you change signs”) is given using esoteric terminology (and also in code) and appears third in a list of Rules mostly having nothing to do with working out the actual exercises. The first thing I’d do if I had a free hand is throw out this book.

### It Never Ends

$\bullet$Keith Devlin interviewed in Text Savvy (and a partial catalogue for the “repeated addition” flap by Jonathan).
$\bullet$“Is the Public Hungry for Math?” (PDF), by Douglas N. Arnold in October’s Notices.
$\bullet$The Unapologetic on student evaluations.

### Promises, Promises

Classes start tomorrow … and my “retirement” ends (I took the summer off). Probably I’ll start posting pretty regularly again. There’s a five-day-a-week class in there (9 AM, no less) so I’ll sure as heck be here. As of now I have no mailbox or either of the books. I’ve looked over the syllabus for the “Analysis for Business” and am pleasantly surprised to see much more “analysis” (pre-calc, really) than “business”. The financial stuff is mostly at the end of the quarter so I’ll have plenty of time to figure it out before I have to present it.

### Classes Start In A Week

$\bullet$Tools for math websites at squareCircleZ.
$\bullet$In praise of proving that zero equals one by Matt Epsilonica.

### Not Late For Dinner

$\bullet$The creator of God Plays Dice—the essential Math Blog— is now posting as Michael Lugo.
$\bullet$Halfway There just had a third birthday.
$\bullet$Borovik and Corfield are organizing a Philosophy of Mathematics Workshop.
$\bullet$Daniel Lemire’s blog was recently hacked.
$\bullet$Jon Ingram on Euclid.

• ## (Partial) Contents Page

Vlorbik On Math Ed ('07—'09)
(a good place to start!)