Perchance someone here has some background in Philosophy, specifically symbolic logic? For the life of me I can't figure out the following:(adsbygoogle = window.adsbygoogle || []).push({});

A v D

(~B ^ ~C) = D

B => ~(C=> A)

~B

What I have so far is this:

1| A v D ............................P

2| (~B ^ ~C) = D .............P

3| B => ~(C =>A) ............P

4| |B ................................A

5| | |C .............................A

r| | |?

s| | |?

t| | |?

u| | |?

v| | |A ..............................1, ?-?, ?-?, vE

w| | C=>A ........................5-v, =>I

x| | B => ~(C =>A) ..........2, R

y| | ~(C =>A) ..................w, x, =>E

z| ~B ...............................4, w, y, ~I

What I can't figure out is how to get the disjunction elimination for A in the second sub-derivation. Anyone have a clue?

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# Homework Help: Need Help

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