Question 1
Consider this proof, (1.)E /∴ C v (E v D) (2.) E v D (3.) (E v D) v C (4.) C v (E v D) What is the justification for line 4?
◦ 3, DM
◦ 3, Com
◦ 1,3 DS
Question 2
Consider this proof, (1.)E•[~I •(~DvI)] /∴ ~DvF (2.)[~I •(~DvI)]•E (3.(~I •(~DvI) (4.) ~ I (5.) (~ D v I) • ~ I (6.) ~ D v I (7.) ~ D (8.) ~ D v F What is the justification for line 8?
◦ 7 Simp
◦ 7 Add
◦ 6, 7 DS