Re: [請益] Walrasian budget set 的 Convexity 問題

看板Economics (經濟學)作者 (insight)時間18年前 (2008/01/22 00:30), 編輯推噓1(100)
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※ 引述《washburn (Just a game)》之銘言: By definition, If X is a convex set, then : x'' = alpha*x + (1-alpha)*x' belongs to LR+, for any alpha belongs to [0,1]. To show B{p,w} is convex, for any a, b belong to B{p,w}, we need to show that c= alpha*a + (1-alpha)*b also belongs to B{p,w}. First, c belongs to LR is obvious. Second, p*c=p*(alpha*a + (1-alpha)*b) =alpha*p*a+(1-alpha)*p*b <=alpha*w + (1-alpha)*w <= w By definition, B{p,w} is a convex set. Q.E.D. : Walrasian budget set:B {p,w} = {x belongs to LR: p*x <= w}。 : 請問,為什麼在 X 為 convex 時,B {p,w} 也是 convex? -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 122.124.125.58 ※ 編輯: welly 來自: 122.124.125.58 (01/22 00:31)

01/22 00:33, , 1F
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01/22 00:33, 1F
文章代碼(AID): #17bCYHpQ (Economics)
文章代碼(AID): #17bCYHpQ (Economics)