Our 15th year of the Girls’ Angle Bulletin begins with Part 1 of a multi-part interview with University of Wisconsin, Madison Associate Professor of Mathematics Tullia Dymarz. This was our first interview conducted over Zoom. In this first part, Tullia beautifully explains the notion of quasi-isometry and one of her favorite objects of study, the Diestel-Leader graph as the Cayley graph of the lamplighter group.

For this interview, we benefitted greatly from a biographical sketch of Tullia written by Isa Barth, and Isa’s essay follows the interview, although we urge all readers to read Isa’s essay first, as our interview takes off from there.

If you’ve been looking for an application of pipe cleaners to mathematics, look no further… Tullia provides a super interesting one!

Next, University of Oregon Associate Professor of Mathematics Ellen Eischen presents a selection of images from a mathematical art show that she curated and organized called *Creativity Counts* and which was on display at the Jordan Schnitzer Museum of Art in Eugene, Oregon. The cover features a contribution by Ellen herself. As Ellen note, “Aesthetic aspects of number theory, an area illustrated in most of the pieces in the gallery, have enthralled mathematicians since antiquity.”

Many topics in mathematics lend themselves well to visual imagery. If you create mathematically inspired visual art, we’d love to see it!

Anna Ma shows us that the Kaczmarz algorithm is an instance of a much more general minimization algorithm called “gradient descent.” If you have a real-valued function defined on some *n*-dimensional real space, and it is differentiable, then at each point in the *n*-dimensional space, it will have a vector, called the gradient, which points in the direction that the function locally grows the fastest. Gradient descent algorithms attempt to find minima by moving in a direction opposite to where the gradient points.

Emily and Jasmine analyze the Valentine heart equation from the Valentine heart app that launched their Valentine heart journey. They identify the 2D cross section which corresponds to the heart shape and compare and contrast it with the equation that they concocted.

We conclude with a few Notes from the Club.

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!