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From: cchikakoo@yahoo.co.jp
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Subject: Re: $B@~7ABe?t$ND>OBJ,2r$NLdBj$G<ALd$G$9 (B
Date: Sat, 11 Oct 2008 23:25:31 -0700 (PDT)
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Sylvesterの定理は各空間に基底を与えるのかもしれません。

V_p=Span of the positive elements of the basis
V_n=Span of the negative elements.

つまり,
V_p:=span{v∈V;もしv≠0なら<v,v>>0}
V_n:=span{v∈V;もしv≠0なら<v,v><0}
これなら線形部分空間になりますよね。

と書けるのではないでしょうか??