想请教高手 1.) Prove A v A v A |- B -> A 下面应该是属於论述逻辑? (Predicate Logic) 2.) |- (for all x)(A -> B -> C) -> (for all x)(A -> B) -> (for all x)(A -> C) 3.) Prove by induction on terms, that for any terms t and s, if s is a prefix of t, then the strings t and s must be identical. 我承认是问功课.... 但我真的想不出来要怎麽证明?..... 第一题只有一边有B 是要怎麽搞 Orz..... 题外话 学期快结束了 我还真好奇我怎麽存活到现在 囧.. 感谢各位的帮忙 T_T -- The world ain't all sunshine n rainbows.It's a very mean n nasty place. N it'll beat u to ur knees n keep u there permanently if u let it. You,me or nobody's gon hit as hard as life. But it ain't about how hard u hit. It's about how hard u can get hit;how hard u can take,n keep movin forward.If u know what u'r worth, then go out n get what u'r worth. But u gotta be willing to take the hit, n not pointing fingers saying u ain't where u r becuz of him, or her or anybody. --

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