On some k-fold generalizations of Lov\'asz theta and their sandwich theorems
We study several $k$-fold generalizations of the Lov\'asz theta function associated with the maximum $k$-colorable induced subgraph problem. The first is the Narasimhan--Manber parameter $\vartheta_k$. We prove that, for graphs whose adjacency matrix belongs to a homogeneous partially coherent algebra, this parameter i...