Question 869967
<pre>
1.  ~(X * Y) > Z
2.  Z > Y
conclusion: Y
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3.  ~~(X * Y) v Z                         1          Material Implication       
4.  (X * Y) v Z                           3          Double Negation        
5.  Z v (X * Y)                           4          Commutation
6.  (Z v X) * (Z v Y)                     5          Distribution
7.  (Z v Y) * (Z v X)                     6          Commutation
8.  Z v Y                                 7          Simplification
9.  Y v Z                                 8          Commutation
10. ~~Y v Z                               9          Double Negation
11. ~Y > Z                                10         Material Implication  
12. ~Y > Y                                11,2       Hypothetical Syllogism
13. ~~Y v Y                               12         Material Implication 
14. Y v Y                                 13         Double Negation 
15. Y                                     14         Tautology
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Note: I'm used to the term "Material Implication" instead of just "Implication" but they're the same idea.