SB-labelings and posets with each interval homotopy equivalent to a sphere or a ball

We introduce a new class of edge labelings for locally finite lattices which we call SB-labelings. We prove for finite lattices which admit an SB-labeling that each open interval has the homotopy type of a ball or of a sphere of some dimension. Natural examples include the weak order, the Tamari lattice, and the finite distributive lattices.