O0017600 (ŏb-vûr′zhən, əb-)n.1. The process of obverting or the condition so resulting.2. Logic Inference of the obverse of a proposition.
ob•ver•sion
(ɒbˈvɜr ʒən, -ʃən)
n. 1. an act or instance of obverting. 2. a form of inference in which a negative proposition is obtained from an affirmative, or vice versa, as “None of us is immortal” is obtained by obversion from “All of us are mortal.” [1840–50; < Late Latin]EncyclopediaSeeObversion