Chains in lattices of mappings and finite fuzzy topological spaces

In this paper, we establish several results concerning chains in YX, the lattice of mappings from a finite set X into a finite totally ordered set Y. We compute the total number and the cardinalities of several collections of chains. As a byproduct we determine the total number of chained Y-fuzzy topologies defined on X. Several related and other well known results are obtained as corollaries. Also some natural questions are presented for further investigations.