document.write( "Question 1171838: 1. A v B
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Algebra.Com's Answer #796751 by Edwin McCravy(20055)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "With \"Material Equivalence\" you can replace \r\n" );
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document.write( "p ≡ q   by  (p ⊃ q) & (q ⊃ p)\r\n" );
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document.write( "1. A v B \r\n" );
document.write( "2. A ≡ (C & D) \r\n" );
document.write( "3. B ⊃ (D & G)      /D\r\n" );
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document.write( "                | 4. ~D                 Assumption for Indirect Proof\r\n" );
document.write( "                | 5. [A ⊃ (C & D)] & [(C & D) ⊃ A) 2, Material Equivalence \r\n" );
document.write( "                | 6. ~D v ~C                        4, Addition\r\n" );
document.write( "                | 7. ~C v ~D                        6, Commutation\r\n" );
document.write( "                | 8. ~(C & D)                       7, DeMorgan's law\r\n" );
document.write( "                | 9. A ⊃ (C & D)                    5, Simplification\r\n" );
document.write( "                |10. ~A                             9,8, Modus tollens\r\n" );
document.write( "                |11. B                              1,10, Disjunctive Syllogism  \r\n" );
document.write( "                |12. D & G                          3,11, Modus ponens\r\n" );
document.write( "                |13. D                              12, Simplification\r\n" );
document.write( "                |14. D & ~D                         13,4, Conjunction\r\n" );
document.write( "15. D                Lines 4-14  Indirect Proof\r\n" );
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document.write( "Edwin
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