18th Meetup: The sum of all squares and study of collaboration networks

For the Meetup of February we will again offer a brain challenging evening. Andrew Tweddle will challenge us with various approaches to tackling the sum of squares problem. With Steven Taschuck we will discuss a paper about a collaboration network that is derived from the Marvel Universe. In the two abstracts below we provide more information on these talks.

The sum of all squares, by Andrew Tweddle (http://andrewtweddle.blogspot.ca/).

Abstract: How many squares are there on a chessboard? Include squares of all sizes: 1 x 1, 2 x 2 up to 8 x 8.More generally, how many squares are there on an n by n grid expressed as a function of n? Solve this problem in as many different ways as you can.Andrew Tweddle will be presenting a variety of solutions - algebraic, combinatorial and visual. Feel free to bring your own solutions for discussion. Let's see if we can find a particularly elegant solution to this problem.If time permits, Andrew will also demonstrate iPython and SymPy for automating some of the algebra.

Marvel Universe looks almost like a real social network (paper by R. Alberich, J. Miro-Julia, F.Rossello), (http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.332.2051&rep=rep1&type=pdf) presented by Steven Taschuck (http://www.amotlpaa.org/)

Abstract: We investigate the structure of the Marvel Universe collaboration network, where two Marvel characters are considered linked if they jointly appear in the same Marvel comic book. We show that this network is clearly not a random network, and that it has most, but not all, characteristics of “real-life” collaboration networks, such as movie actors or scientific collaboration networks. The study of this artificial universe that tries to look like a real one, helps to understand that there are underlying principles that make real-life networks have definite characteristics.