...-... Algebras.
We introduce some particular classes of filters and order-ideals in distributive semilattices, called -filters and -order-ideals, respectively. In particular, we study -filters and -order-ideals in distributive quasicomplemented semilattices. We also characterize the filters-congruence-cokernels in distributive quasicomplemented semilattices through -order-ideals.