Question 1144033
Construct a formal proof of validity for the following argument

~B v [(C⊃D) · (E⊃D)]

B · (C v E)

Therefore, D

<pre>
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NOTE: Using
  & for "AND" 
  v for "OR"
  --> for  "implies"
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1. ~B v ((C-->D) & (E-->D))  Premise
2. B & (C v E)               Premise
3. B                         2 Simplification (SIMP)
4. ((C-->D) & (E-->D))       3,1 Conditional Disjunction (CD)
5. C v E                     2 SIMP
6. :: C                      Conditional Proof (CP) assumption #1
7. :: D                      6,4 Modus Ponens (MP)
8. :: E                      CP assumption #2
9. :: D                      8,4 MP
10.:: (C V E) --> D          6-9 Proof by Cases (PBC)
11. D                        5,6-10  CP