Subtraction-like Operations in Nearsemilattices

A nearsemilattice is a poset having the upper-bound property. A binary operation − on a poset with the least element 0 is said to be subtraction-like if x ≤ y if and only if x − y = 0 for all x, y. Associated with such an operation is a family of partial operations lp defined by lp(x) := p − x on every initial segment [0, p]; these operations are thought of as local (sectional) complementations of some kind. We study several types of subtraction-like operations, show that each of these operations can be restored in a uniform way from the corresponding local complementations, and state some connections between properties of a (sufficiently strong) subtraction on a nearsemilattice and distributivity of the latter.