 Proceeding in this way through his table of relations among ideas, Bolzano obtains at one stroke a complete system of extensional relations between propositions, relative to certain of their parts considered variable (in other words, between propositional forms in the sense of classes of propositions). The result is a genealogical tree whose fundamental structure is exactly the same as the structure of the tree representing the relations between ideas. In most cases, he uses the same terms, speaking of compatibility, deducibility (inclusion), subordination (unilateral deducibility), equivalence (mutual deducibility), overlapping, contrariety, and contradiction among propositions. 