Quasivarieties of pseudocomplemented semilattices
M. E. Adams, Wiesław Dziobiak, Matthew Gould, Jürg Schmid · Fundamenta Mathematicae · 1995
Two properties of the lattice of quasivarieties of pseudocomplemented semilattices are established, namely, in the quasivariety generated by the 3-element chain, there is a sublattice freely generated by ω elements and there are $2^ω$ quasivarieties.