‘Expander Graphs and the Zig-Zag Product’

Over the past 30 years, the theory of expanders has become a fruitful area of research in pure and applied math with applications to number theory, group theory, and error correcting codes. Yale University has contributed significantly to this field through the works of Professor Margulis, Professor Lubotzky, and Professor Spielman. After defining expander families and considering the difficulty of their explicit construction, we will examine one method of construction developed by Reingold, Vadhan, and Wigderson using the zig-zag product.