document.write( "Question 928646: I need to somehow get ~K as the conclusion, using natural deduction (This means the 18 rules of natural deduction, Modus Ponens, Modus Tullens, De Morgan's Rule etc etc.) \r
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\n" ); document.write( "\n" ); document.write( "1. K ⊃ L
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Algebra.Com's Answer #564734 by Edwin McCravy(20055)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "I use slightly different symbols than you,\r\n" );
document.write( "but you can figure them out:\r\n" );
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document.write( " 1. K->L	\r\n" );
document.write( " 2. ~KvF	\r\n" );
document.write( " 3. (L&F)->A	\r\n" );
document.write( " 4. ~A\r\n" );
document.write( "      // ~K\r\n" );
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document.write( " 5. ~A->~(L&F)        3, contrapositive\r\n" );
document.write( " 6. ~(L&F)            5,4 hypothetical syllogism\r\n" );
document.write( " 7. ~Lv~F             6, deMorgan's\r\n" );
document.write( " 8. ~L->~K            1, contrapositive\r\n" );
document.write( " 9. K->F              2, writing a disjunction as a conditional\r\n" );
document.write( "10. ~F->~K            9, contrapositive\r\n" );
document.write( "11. ~Kv~K             8,10,7, constructive delimma   \r\n" );
document.write( "12. ~K                11, idempotent law\r\n" );
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document.write( "Edwin
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