P: X → not DP: ? P: B → DC: B → A

3scobar14 August 5, 2019

Not A > X???

If P: X > Not D D > Not X P: ? P: B> D Not D > Not B C: B > A Not A > Not B So Not A = Not D Making X = Not D Not A > X > Not D > Not B Not A > X Not X > A Why does X go before not A as opposed to X going after not A ?

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Irina August 8, 2019

@3scobar,

I am not sure I understand your question. Your diagram looks correct.

(1) X -> ~D
(2) ?
(3) B- >D
________
C: B ->A

(1) X -> ~D
(2) ?
(3) B- >D
(4) D -> ~X (1) contrapositive
(5) B-> ~X (3) (4) composition

Now to get from
B -> ~ X to
B -> A

the missing premise must be;
~ X -> A or
~ A- > X

Please let me know if you have any further questions.