## Girls’ Angle Bulletin, Volume 12, Number 2

We open with the second part of a multi-part interview with mathematician Dr. Kristin Lauter, a professor at the University of Washington and a principal researcher at Microsoft Research. In this segment, Dr. Lauter gets into the nitty-gritty details of the Diffie-Hellman protocol for public key exchange and begins to explain what elliptic curves have to do with cryptography.

Next, Prof. Needell teases us with some tantalizing probability questions to underscore just how subtle and surprising probability can be.

Alana Axelrod-Freed, Milena Harned, and Miriam Rittenberg show how they proved a nifty result pertaining to paper folding that they discovered last summer. They were exploring the so-called “stamp folding problem” which asks for the number of ways a row of n stamps can be folded up by folding along the creases between stamps. This is an unsolved problem. However, they restricted to counting a certain subset of the folds and were able to get an explicit answer.

Emily and Jasmine begin a new math adventure exploring the areas of regions obtained by drawing zigzags across the face of a rectangle.  The cover shows an example of such a dissection. Will they find any interesting patterns? What patterns will they find?

Next, we have an article that aims to help those who are struggling to understand a fourth spatial dimension. The strategy presented is a pair of parallel dialogues that is based on work I did with eighth graders at the Buckingham, Browne, and Nichols Middle School that seemed to be fairly effective at helping them move into the fourth dimension.

Milena and Miriam return with the second part of our article on Umbrellas. Here we complete the proof of a characterization of the locus of points reachable in n unit-length step from the origin, such that each step has a nonnegative vertical component.

We close 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!

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