propositional calculus

(SL = Sentential Logic) Every theorem of classic sentential logic is a theorem.

Suppose the diagram was frozen with its initial information, and the sentential logic was augmented by the ability to observe truths from this frozen diagram to form a reasoning system which we might label Observationally Augmented Sentential Logic (OASL).

Of these three chapters, the most fascinating is that treating molecular propositions since it not only adverts, in general, to parallel treatments in modern sentential logic but also shows the extent to which medieval logicians constructed formal inference rules of the highest level of abstraction, centuries before such rules were "discovered" in the development of modern mathematical logic.