Frequent universality criterion and densities. (arXiv:1807.04171v1 [math.FA])

We improve a recent result by giving the optimal conclusion possible both to the frequent universality criterion and the frequent hypercyclicity criterion using the notion of A-densities, where A refers to some weighted densities sharper than the natural lower density. Moreover we construct an operator which is logarithmically-frequently hypercyclic but not frequently hypercyclic. 查看全文>>