In this paper, we introduce
the notion of D-complexes which are defined by replacing metric spaces with
Nagami’s D-spaces in the definition of Hyman’s M-spaces, and prove a main theorem
that every D-complex is a space with a σ-almost locally finite base (this notion was
introduced by Itō and Tamano). This theorem sharpens a theorem of Nagata.
Furthermore, we deal with the adjunction spaces of two spaces with a σ-almost
locally finite base.