Epistemology
The word "epistemology" is derived from the ancient Greek "epistēmē" meaning "knowledge" and the suffix "-logy", meaning "logical discourse" (derived from the Greek word "logos" meaning "discourse"). It is analogue to the German "Wissenschaftslehre" (literally, theory of science) which was introduced by philosophers Johann Fichte and Bernard Bolzano in the late 18th century. The word first appeared in English in 1847 as a translation of the German in New York's "Eclectic Magazine" review of a philosophical novel by German author Jean Paul:
Dynamic epistemic logic
Dynamic epistemic logic (DEL) is a logical framework dealing with knowledge and information change. Typically, DEL focuses on situations involving multiple agents and studies how their knowledge changes when events occur. These events can change factual properties of the actual world (they are called "ontic events"): for example a red card is painted in blue. They can also bring about changes of knowledge without changing factual properties of the world (they are called "epistemic events"): for example a card is revealed publicly (or privately) to be red. Originally, DEL focused on epistemic events. We only present in this entry some of the basic ideas of the original DEL framework; more details about DEL in general can be found in the references.