I’m trying to create exercises for myself to make sure I have contraposition, obversion, etc down before I move on to the next lecture. So here’s one I created and if it’s wrong in anyway someone please let me know.
If we start with the proposition. “All heat pumps are airconditioners.”
Jerryb225: Your worked example is correct. Where ‘-‘ stands for a complement:
HAS becomes -SA-H, by contraposition (contraposition valid on O and A types)
-SA-H becomes -SEH by obversion (obversion valid on A, E, I, O)
-SEH becomes HE-S by conversion, (conversion valid on I and E types) and
HE-S becomes HAS by obversion (obversion valid on A, E, I, and O)
I think you’ll agree that it’s not easy to see the equivalency of these four propositions in English!