Definition2. ( Demographics Generality) Demographics criteria d is more(less) general than d"if: ∀(di,d" i): d" i ∈di (di∈d" i). We denote these relationships as d≺d" (d%d").
All demographics criteria and their generality relationships form a demographics lattice L, with a size equal to the product of the hierarchies’ sizes. We show an example of such a lattice in the right part of Figure 1, where a nine-element demographics lattice is formed by all node combinations of two hierarchies, each containing three nodes (shown left). The links that go from one lattice node to another indicate generality relations. For example, such criteria as {Italy, Student} and {France, Student} are less general than {Europe, Student}, which is itself less general than {Europe, Academic}.