Semi-closure mappings and cofinal chains
In a former paper, motivated by a recent theory of relators (families of relations), we have investigated increasingly regular and normal functions of one preordered set into another instead of Galois connections and residuated mappings of partially ordered sets. A function of one preordered set into another has been called (1) increasingly -normal, for some function of into , if for any and we have if and only if ; (2) increasingly -regular, for some function of into itself,...
The investigation of orthocomplemented lattices with a symmetric difference initiated the following question: Which orthomodular lattice can be embedded in an orthomodular lattice that allows for a symmetric difference? In this paper we present a necessary condition for such an embedding to exist. The condition is expressed in terms of -valued states and enables one, as a consequence, to clarify the situation in the important case of the lattice of projections in a Hilbert space.