<PRE><B>Question 1029804</B>
1. D v Y   --------------------Hypothesis
2. ~~D v Y --------------------double negation
3. ~D &amp;#8835; Y ---------------------material implication
4. Y &amp;#8835; ~(Z &amp;#8835; D) ---------------hypothesis
5. Y &amp;#8835; ~(~Z v D) --------------M.I.
6. Y &amp;#8835; (Z &amp; ~D) ---------------double neg. and deMorgan&#39;s law
7. ~Yv(Z &amp; ~D) ----------------M.I.
8. (~Y v Z)&amp;(~Y v ~D)-----------distributivity
9. ~Y v ~D  -------------------simplification
10. Y &amp;#8835; ~D  -------------------M.I.
11. (~D &amp;#8835; Y)&amp;(Y &amp;#8835; ~D) ---------conjunction on #3 and #10 
12. Y &amp;#8801; ~D -------------------- #11 and logical equivalence for &amp;#8801; </PRE>