[jerry3643]

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.”

H = heat pumps
S = airconditioners

[jerry3643]

Sorry correction..

H A S = All heat pumps are airconditioners
~S A~H = All non-airconditioners are non heat pumps
~S E H = No non airconditioners are heat pumps
H E ~S = No heat pumps are non airconditioners

LOl so aggravating ….

[gerard.casey]

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!

[jerry3643]

thank you very much Dr Casey

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