| [ Christian ] in KIDS 글 쓴 이(By): parsec ( 먼 소 류 ) 날 짜 (Date): 2001년 12월 8일 토요일 오후 10시 09분 41초 제 목(Title): Re: about procedure Anyway, what's the difference between the following "they"? 1) X ∪ X^C = U :complement 2) X ∩ X^C = φ :conflict They are logically equivalent from definition of complement set. X^C. What's the logical base which makes those two different? If you don't have, I will say your thought is illogical. (your distinguish between complement and conflict is illogical) ------------------ If you want my comment about the logical realtion of the two, I didn't say ther were different. Nor that they were equal. They are both part of the definition of complement set. But in general case, say set A and set B, i) A ∪ B = U and ii) A ∩B = φ are not equivalent. Nor they are contradictory. For two sets that satisfy both relation, they are called complementary. But i) do not follow from ii) logically and vice versa. For the complementary sets above, 1) and 2) do not follow from each other. They both follow from the definition of X^C, or rather, they comprise the definition of X^C together. But generally the two statements are independent. ◇ ~~~_ _ ∴ ~|~| | _/__, SEP. 11. 2001 _ ∴∴ _ ~ | | ＼ ` Armorica under a tat ,-| `,-,_| |__ | | | A ______|_|__|_|___|__|| | |__|_|_____________________________________ |