document.write( "Question 1156932: Use natural deduction to derive the conclusion in each problem.\r
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\n" ); document.write( "\n" ); document.write( "Use an ordinary proof (not conditional or indirect proof):
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\n" ); document.write( "\n" ); document.write( "1. (O ⊃ C) • (∼S ⊃ ∼D)
\n" ); document.write( "2. (E ⊃ D) • (∼E ⊃ ∼C) / O ⊃ S \n" ); document.write( "
Algebra.Com's Answer #779987 by Edwin McCravy(20060)\"\" \"About 
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document.write( "1.	(O ⊃ C) • (∼S ⊃ ∼D)	 \r\n" );
document.write( "2.	(E ⊃ D) • (∼E ⊃ ∼C)	 / O ⊃ S\r\n" );
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document.write( "3.       O ⊃ C                 1, Simplification\r\n" );
document.write( "4.      (∼E ⊃ ∼C) • (E ⊃ D)   2, Commutation\r\n" );
document.write( "5.       ∼E ⊃ ∼C              4, Simplification\r\n" );
document.write( "6.       ∼∼C ⊃ ∼∼E            5, Transposition\r\n" );
document.write( "7.       C ⊃ E                 6, Double Negation\r\n" );
document.write( "8.       O ⊃ E                 3,7, Hypothetical Syllogism\r\n" );
document.write( "9.       E ⊃ D                 2, Simplification\r\n" );
document.write( "10.      O ⊃ D                 8,9, Hypothetical Syllogism\r\n" );
document.write( "11.     (∼S ⊃ ∼D) • (O ⊃ C)   1, Commutation\r\n" );
document.write( "12.      ∼S ⊃ ∼D              11, Simplification\r\n" );
document.write( "13.      ∼∼D ⊃ ∼∼S            12, Transposition\r\n" );
document.write( "14.      D ⊃ S                 13, Double Negation\r\n" );
document.write( "15.      O ⊃ S                 10,14, Hypothetical Syllogism\r\n" );
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document.write( "Edwin
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