Semidefinite relaxations for sparse Max-Cut problems Angelika Wiegele We investigate semidefinite relaxations of the Max-Cut problem, which are formulated in terms of the edges of the graph, thereby exploiting the (potential) sparsity of the problem. We show how this is related to higher order liftings of Anjos and Wolkowicz and Lasserre. Contrary to the basic semidefinite relaxation, which is based on the nodes of the graph, the present formulation leads to a model which is significantly more difficult to solve. We present preliminary computational results using the spectral bundle method where we make partial use of second-order information. These results indicate that this model is manageable for sparse graphs on a few hundred nodes and yields very tight bounds. (joint work with F. Rendl)