lattice (n.)

A concept from abstract algebra, sometimes applied in SEMANTIC theory to model MEREOLOGY (part/whole relations). A lattice is a structured set in which every pair of elements has a ‘join’ (SUM) as well as a ‘meet’ (or ‘product’), conforming to certain conditions. Sometimes the weaker notion of a semi-lattice is used instead, requiring every pair of elements to have a sum but not necessarily a product.