Given the argument:
1. G ⊃ (H ⊃ K)
2.(H ∨ ∼M) ⊃ ∼K
3. H / ∼G
4. H ∨ ∼M 3, Addition
5. ~K 2, Modus ponens
6. (G • H) ⊃ K 1, importation
7. ~(G • H) 6,5 Modus ponens
8. ~G ∨ ~H 7, DeMorgan's
9. ~~H 3, Double negation
10. ~G 8,9, Disjunctive syllogism
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Identify the rules of replacement/inference used to derive the proposition:
(G • H) ⊃ ~K?
Sorry, that's not true in the above case as you see by step 6.
Edwin