Köthe spaces modeled on spaces of functions
The isomorphic classification problem for the Köthe models of some function spaces is considered. By making use of some interpolative neighborhoods which are related to the linear topological invariant and other invariants related to the “quantity” characteristics of the space, a necessary condition for the isomorphism of two such spaces is proved. As applications, it is shown that some pairs of spaces which have the same interpolation property are not isomorphic.