Question 935456
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1.	A&#8594;B
2.	A&#8594;~(C&#8744;B) &#8756; ~A 

3.      A&#8594;(~C&~B)      2, DeMorgan's theorem
4.      A&#8594;~B           3, Decomposition (simplification) of a conjunction
5.      ~B&#8594;~A          1, Modus Tollens
6.      ~~B&#8594;~A         4, Modus Tollens
7.      B&#8594;~A          7, Double negation
8.      B&#8744;~B          Tautology (law of excluded middle)
9.       ~A             7,5,8, disjunctive elimination (disjunctive syllogism)      

 

1.	(A&~B)&(~C&#8744;D)
2.	~[(D&A)&~B] &#8756; ~C

3.      ~[D&(A&~B)]      2,Association
4.      ~D&#8744;~(A&~B)        3,DeMorgan's theorem 
5.      A&~B             1,Decomposition (simplification) of a conjunction  
6.      ~D               4,5, disjunctive elimination (disjunctive syllogism) 
7.      ~C&#8744;D             1,Decomposition (simplification) of a conjunction
8.      ~C               7,6, disjunctive elimination (disjunctive syllogism) 

Edwin</pre>