MA121 Lecture 2: 备注 2019年1月24日
Document Summary
If x is even then 9 is odd by contraposits. If 3319 is even then x is odd. 2ck tautology pisqipsq. is i prove if p thenq first i write usedirect hen assume p next finally. Therefore x xttjtltsdd. ae heproudthatthegin statement proud lhallheorgmals. ca men goredediifx. yareadgeentz. ximandy. mn then one is odd and the other is even. Henan product of two agent z is even mii mlmtlji2ikczk. tl. If nis an integer then in ti is odd it n_n were not odd even is even pmfif. sume that it in n would be odd muti. Therefore the sumptimattbeginingtswmg. in other words theproductof two agent z it n ti is odd. Here we prove ptsqby assume p and uq and then find a contradiction to some known results cfs definitiontheory siuep qupnq. gr cj ucnpvq q pnuqllthpmggmtrz ug. Method ofproof by antradition ifp thenq proof iassume p and not q. Tf iassumethat anb aubbut at b so eitherthere is xgabut xgb or there is x eb but x ga.
