Free food! From Typhoon! Also, math. **The Sexy Primes** (Undergrad Math Club) present:

Knots and the Fourth Dimension with Professor Constance Leidy!

Take a piece of string, jumble it up, then seal the ends together. The result is a knot. Notice that you can’t untie the knot because you’ve permanently sealed the ends together. (If we don’t jumble at all, we’ll just end up with a circle, which we call the unknot.) We call two knots equivalent if you can move one jumbled piece of string to look exactly like the other without cutting it open. Knots naturally live in 3-space. We’ll discuss a different equivalence relation called concordance involving the fourth dimension. A knot that is concordant to the unknot is called a slice knot. We will discuss some joint work that shows that knots in a certain family whose slice status was unknown are in fact not slice.

**Date: ** Oct. 11

**Time:** Noon – 1:00 PM

**Place:** Woodhead Lounge, Exley Science Center

**Cost: ** Free!