Monday, Feb. 15, 4:35-5:30 in 901 Van Vleck Math club's second meeting of the semester will involve a presentation by Zachary Charles. More information on the talk can be found below. Abstract: An addition chain is a sequence of numbers starting at one, such that every number is the sum of two previous numbers. What is the shortest chain ending at a number n? While this is already a difficult question, we will talk about how addition chains answer more challenging questions, including: How do we compute 2^4? What can the Ancient Egyptians teach us about cryptography? What about subtraction? We will discuss the applications of addition chains to cryptography, especially the Diffie-Hellman key exchange. Time permitting, we will briefly introduce addition-subtraction chains and explain their link to elliptic curve cryptography. This talk is meant as an introduction to how we use mathematics in computer programming. No background is assumed.