Short answers, pulled from the story.
Chrysippus developed a deductive system for propositional logic in the 3rd century BC. His work focused on propositions rather than terms, distinguishing it from traditional syllogistic logic.
Most of Chrysippus original writings were lost between the 3rd and 6th century CE. Stoic logic faded into oblivion until its resurrection in the 20th century.
Propositional variables serve as atomic formulas within formal languages. These variables typically appear as capital roman letters like P, Q, and R.
Classical logic assigns exactly two truth values: true and false. Every proposition evaluates to precisely one of these semantic values.
The DPLL algorithm emerged in 1962 as one practical solving method. Determining satisfiability constitutes an NP-complete problem within computational complexity theory.