document.write( "Question 1029805: Please solve using natural deduction (only rules of implication + rules of replacement). Thx!\r
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Algebra.Com's Answer #644740 by Edwin McCravy(20055)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "This one involves material implication \r\n" );
document.write( "P ⊃ Q is equivalent to ~P v Q\r\n" );
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document.write( "1. A ⊃ U\r\n" );
document.write( "           / A ⊃ (K ⊃ U)\r\n" );
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document.write( "2. ~A v U           1, Material implication\r\n" );
document.write( "3. ~A v (U v ~K)    2, Addition  \r\n" );
document.write( "4. ~A v (~K v U)    3, Commutation\r\n" );
document.write( "5. A ⊃ (~K v U)     4, Material implication\r\n" );
document.write( "6. A ⊃ (K ⊃ U)      5, Material implication\r\n" );
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document.write( "Edwin
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