## Girls’ Angle Bulletin, Volume 16, Number 1

Volume 16, Number 1 opens with an interview with Professor Ann Trenk. Professor Trenk is the Lewis Atterbury Stimson Professor of Mathematics at Wellesley College. We thought it appropriate to include her interview in this issue because she briefly touches on partially ordered sets, which is the topic of Robert Donley’s article Examples of Posets which appears on page 13.

High school sophomore, Emily Caputo presents us with a challenge: to figure out what image she is depicting by the solutions to 24 different sets of simultaneous equations and inequalities. (See page 7.) Ever since Descartes introduced coordinates, geometry and algebra have been inextricably linked!

Emily and Jasmine begin a new adventure. On social media, they read that one can list the nonnegative rational numbers by using the function $f(x) = 1/(1+[ x ] -\{ x \})$, where $[x]$ is the greatest integer less than or equal to $x$ and $\{ x \}$ is the fractional part of $x$, namely $x - [x]$. According to what they read, the sequence $0$, $f(0)$, $f(f(0))$, $f(f(f(0)))$, … is a list of all the nonnegative rational numbers, and they’ve set out to understand and prove this assertion. If you don’t see what all the excitement is all about, please take a look at Addie Summer’s Learn by Doing on page 24.

Finally, Anna Ma explains the perceptron algorithm for finding a linear separator. This algorithm is readily implementable on a computer in your favorite programming language and we encourage you to try it!

We hope you enjoy it!

Finally, a reminder: when you subscribe to the Girls’ Angle Bulletin, you’re not just getting a subscription to a magazine. You are also gaining access to the Girls’ Angle mentors.  We urge all subscribers and members to write us with your math questions or anything else in the Bulletin or having to do with mathematics in general. We will respond. We want you to get active and do mathematics. Parts of the Bulletin are written to induce you to wonder and respond with more questions. Don’t let those questions fade away and become forgotten. Send them to us!

Also, the Girls’ Angle Bulletin is a venue for students who wish to showcase their mathematical achievements that go above and beyond the curriculum. If you’re a student and have discovered something nifty in math, considering submitting it to the Bulletin.

We continue to encourage people to subscribe to our print version, so we have removed some content from the electronic version.  Subscriptions are a great way to support Girls’ Angle while getting something concrete back in return.  We hope you subscribe!