Title: Algorithms for Semi-random Graph Partitioning Problems Abstract: Many combinatorial optimization problems are much simpler in practice than in the worst-case. One of the challenges in the area of approximation algorithms is to explain this phenomenon and to design algorithms that work well in real-life. In this talk, we will discuss one of the models of real-life instances -- the semi-random model, which was originally introduced by Blum and Spencer for the k coloring problem. I will present a new semi-random model for graph partitioning problems and give a constant factor approximation algorithm for semi-random instances of Balanced Cut. Joint work with Yury Makarychev (TTIC) and Aravindan Vijayaraghavan (Princeton)