Lesley Ward: “The Linear Algebra of Internet Search Algorithms”
Professor Lesley Ward of the University of South Australia presented the inaugural lecture in The Michael E. Moody Lecture Series on “The Linear Algebra of Internet Search Algorithms”
Lesley Ward is a recipient of the MAA's Alder Award for Distinguished Teaching, and has held a Prize Teaching Fellowship at Yale, a Postdoctoral Fellowship at the Mathematical Sciences Research Institute (MSRI), and an Evans Instructorship at Rice. Her research is in complex analysis, harmonic analysis, and industrial applications of mathematics. She is proud to have been a member of the HMC Mathematics Department for nine years, before moving to the University of South Australia in 2006.
The lecture took place on Sunday, May 2, 2010, from 4:30–5:30 PM, in HMC's Galileo McAlister lecture hall.
As with all of the college's evening speaker lectures, the talk was aimed at a wide audience and was open to all.
How do web-search algorithms work? Early algorithms just counted the number of times a query word appeared in a given webpage. More recent algorithms rely on “link analysis”, which aims to mine the collective wisdom encoded in the network of links: people make judgements about how useful a given page is for a given topic, and they express these judgments through the hyperlinks they choose to put on their own pages. I will show how linear algebra forms the common underpinning of three link-analysis algorithms for web search: PageRank, HITS, and SALSA. I will also discuss a modification of HITS that originated from a Mathematics Clinic at Harvey Mudd College, and is joint work with several people, including Harvey Mudd College undergraduates.