| Term | Definition |
| contrariety | both statments cannot be both true, but they can be both false |
| subcontreriety | both statments can be true, but they cannot be both false |
| only i and o statements can have the relationship of subcontreriety | only a and e statements can be contrary |
| key point subimplication | subimplication can only exist between pairs of a and i statements and o and e |
| true or false only i and o statements can have the relationship of subcontrariety | true |
| subimplication | subimplication is the relationship between a universal and particular statement of the same quality, in which the truth of the universal necessitates the truth of the particular |