Generalized linkage construction for constant-dimension codes

Abstract: A constant-dimension code (CDC) is a set of subspaces of constant dimension in a common vector space with upper bounded pairwise intersection. We improve and generalize two constructions for CDCs, the improved linkage construction and the parallel linkage construction, to the generalized linkage construction which in turn yields many improved lower bounds for the cardinalities of CDCs; a quantity not known in general.