## Undergraduate Math Bloggers

I was interested seeing how undergraduate math students used blogs (and related platforms, like Tumblr). So I posted a call on Google+ and Twitter: I'm looking for mathematics blogs written by undergraduate students. Any recommendations? I'll retweet/repost them as they come in. — Dave Richeson (@divbyzero) February 17, 2014 I received quite a few links. I’m looking…

## Countability of the rationals drawn using TikZ

I’m continuing my exploration of TikZ (here is my first post about TikZ). I will be showing my Discrete Math class how to “count” the positive rational numbers. (See this old blog post for more information about countable sets.) I used TikZ to create the picture below. Here is the source code for this figure. If you click…

## Bubble diagrams for functions in LaTeX using TikZ

I am teaching Discrete Math this semester (our intro-to-proof course). One of the topics is functions. Not surprisingly my students and I have to draw “bubble diagrams” for functions between finite sets—and we have to include them in LaTeX documents. Rather than simply sketching them in Adobe Illustrator and importing them as graphics, I decided…

## Online LaTeX editors

For the last 10+ years I’ve taught topology using a modified Moore method, also known as inquiry-based learning (IBL). The students are given the skeleton of a textbook; then they must prove all the theorems and solve all of the problems. They are forbidden from looking at outside sources. The class types up their work as…

## Ancient number systems in XeTeX

I am teaching a history of mathematics class this semester. We are beginning with a brief discussion of ancient number systems: Egyptian, Babylonian, Mayan, Chinese, Incan, Greek, Roman, and Hindu-Arabic. As I was writing up the first homework assignment it occured to me that I should investigate whether these numbers could be typeset using LaTeX. It…

## Cantor set applet

I made this Cantor set applet for my Real Analysis class. It is nothing fancy, but it saves me from drawing it on the board.

## Applet to illustrate the epsilon-delta definition of limit

Here’s a GeoGebra applet that I made for my Real Analysis class. It can be used to explore the definition of limit: Definition. The limit of as approaches is , or equivalently if for any there exists such that whenever , it follows that .

## A quick guide to LaTeX

This semester I’ll be teaching real analysis. I am going to have the students type their homework in LaTeX. To make this as easy for them as possible, I will give them a template that is all ready for them to enter their solutions. They shouldn’t have to worry about headers, packages, font sizes, margins,…

## Three geometric theorems

Just for fun I thought I’d share a few interesting geometric theorems that I came across recently. Morley’s miracle In 1899 Frank Morley, a professor at Haverford, discovered the following remarkable theorem. The three points of intersection of the adjacent trisectors of the angles of any triangle form an equilateral triangle. I’ve made a Geogebra…

## Tricks for easily creating BibTeX files

I wrote my last book (my only book, that is) using LaTeX. I had a large bibliography with close to 400 entries. I stored all of the bibliographic items in a BibTeX file (a text file ending in .bib). Each item looks something like this: @book {Richeson:2008, AUTHOR = {Richeson, David S.}, TITLE = {Euler’s gem:…

## Coffee stains and the Simpsons in your LaTeX document

A few weeks ago John D. Cook posted a tweet asking for suggestions for his @TeXtip Twitter feed. Usually @TeXtip posts are useful tips or factual tidbits about the typesetting program. I decided to send him a humorous suggestion instead. He posted the tip on Twitter yesterday. I sent him a link to Hanno Rein’s coffee.sty package…

## Interview on Strongly Connected Components

I had the pleasure of chatting with Samuel Hansen on the telephone a little while ago. Our conversation is now online as Episode 16 of his Strongly Connected Components podcast series. Check it out! While you’re at it, check out his other interviews as well as his other podcast series, Combinations and Permutation (he discussed my book…