換かん質しつ

noun

obversion

Technical term in logic: the inference from a proposition to its obverse, e.g., from 'All S are P' to 'No S are non-P'. Rare outside academic contexts.

• 論ろん理り学がくで「換かん質しつ」とは、命めい題だいの質しつを変かえて同どう値ちな命めい題だいを導みちびく操そう作さを指さす。

  In logic, 'obversion' refers to the operation of changing the quality of a proposition to derive an equivalent one.