# Ramanujan Graphs (V)

#### by Sanming Zhou

Institution: The University of Melbourne
Date: Wed 6th March 2013
Time: 11:00 AM
Location: Room 107, Richard Berry

Abstract: We will review some basic definitions and results in number theory. These will be used later in the construction of the expander family $\{X^{p, q}\}$ of Lubotzky, Phillips and Sarnak. Topics to be discussed this week include: sums of two squares, Gaussian integers and their properties, and the famous quadratic reciprocity.