Group Theory — from Wolfram MathWorld

The study of groups. Gauss developed but did not publish parts of the mathematics of group theory, but Galois is generally considered to have been the first to develop the theory. Group theory is a powerful formal method for analyzing abstract and physical systems in which symmetry is present and has surprising importance in physics, especially quantum mechanics.

Theory – Microsoft Research

From the page: “Theory Group

The Theory Group was founded in 1997 by Jennifer T. Chayes and Christian Borgs. We work on fundamental problems in mathematics and theoretical computer science, interact extensively with the academic community and collaborate with other researchers at MSR on challenging applied problems. Among the areas of expertise we have are probability theory, combinatorics, statistical physics, metric geometry, fractals, algorithms and optimization.”