On upper bounding Shannon capacity of graph through generalized conic programming

The Shannon capacity of a graph is an important graph invariant in information theory that is extremely difficult to compute. The Lovász number, which is based on semidefinite programming relaxation, is a well-known upper bound for the Shannon capacity. To improve this upper bound, previous research tried to generalize the Lovász number using the ideas from the sum-of-squares optimization. In this paper, we consider the possibility of developing general conic programming upper bounds for the Shannon capacity, which include the previous attempts as special cases, and show that it is impossible to find better upper bounds for the Shannon capacity along this way.