Mereology - the study of part whole relationships
Tautology - formula which is true in every possible interpretation
Transitivity - if b is part of a, and a is part of e, then by natural extension, b is part of e.
Rigid - necessarily so. For instance 'human' has a rigid property because all instances of human necessarily so. ... can also be defined by signifying the same thing in every instance.
Non-Rigid - not necessarily so. For instance 'studnt' is non rigid because not all instances of a student are necessarily so. A student is a role that can be taken on by a human.
Continuants: exist in full at every instant in time
Occurents unfold over time and never exist in full at any single moment in time.
Subsumption - is-a relationships.
Patromony - is- part of relationships
Cartesian product the direct product of two sets - such that : <ref>Warner, S: Modern Algebra, page 6. Dover Press, 1990.</ref>
Thus it is possible that it will rain today if and only if it is not necessary that it will not rain today;
and it is necessary that it will rain today if and only if it is not possible that it will not rain today.
Sortal' - A sortal is something that takes numerical modifiers