■単純リー環を使った面数数え上げ(その99)
【1】置換多面体の場合
c0=−(a1^2y1+・・・+an^2yn)+(a1^2+・・・+an^2)
h0=|c0|/‖a‖,‖a‖=(a1^2+・・・+an^2)^1/2
ここで,
a1^2+・・・+an^2
=1/2(1/1・2+1/2・3+・・・+1/n・(n+1))
=1/2(1/1−1/2+1/2−1/3+・・・+1/n−1/(n+1))
=1/2(1/1−1/(n+1))
=1/2・n/(n+1)
a1^2y1+・・・+an^2yn
=1/2(1/1・2−1/n(n+1))+・・・+1/2(1/n・(n+1)−1/n(n+1))
=1/2(1/1・2+・・・+1/n・(n+1)−n/n(n+1))
=1/2(1/1−1/(n+1)−n/n(n+1))
h0=(1/2(n+1))^1/2
c1=−(a2^2y2+・・・+an^2yn)+(a2^2+・・・+an^2)
h1=|c1|/‖a‖,‖a‖=(a2^2+・・・+an^2)^1/2
ここで,
a2^2+・・・+an^2
=1/2(1/2・3+・・・+1/n・(n+1))
=1/2(1/2−1/3+・・・+1/n−1/(n+1))
=1/2(1/2−1/(n+1))
=1/2・(n−1)/2(n+1)
a2^2y2+・・・+an^2yn
=1/2(1/2・3−1/n(n+1))+・・・+1/2(1/n・(n+1)−1/n(n+1))
=1/2(1/2・3+・・・+1/n・(n+1)−n/n(n+1))
=1/2(1/2−1/(n+1)−(n−1)/n(n+1))
h1=((n−1)/(n+1))^1/2/n
cn-1=−anxn+an^2=−an^2yn+an^2
hn-1=|cn-1|/‖a‖,‖a‖=(an^2)^1/2
‖ak‖^2=1/2(k+1)(k+2)+・・・+1/2n(n+1)=1/2(1/(k+1)−1/(n+1))=(n−k)/2(k+1)(n+1)
ここで,
an^2=1/2(1/n・(n+1))
=1/2(1/n−1/(n+1))
=1/2(1/n−1/(n+1))
=1/2・1/n(n+1)
an^2yn
=1/2(1/n・(n+1)−1/n(n+1))=0
an^2(1−yn)=1/2n(n+1)
hn-1=(1/2n(n+1))^1/2
一般に,
‖aj‖^2=(n−j)/2(j+1)(n+1)
cj=(n−j)/2n(n+1)
hj={(j+1)(n−j)/2n^2(n+1)}^1/2
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辺の長さを1に規格化する.
Hk=hk/2|x1−a1|=hk/|1−y1|
1−y1=2/n(n+1)
Hk=hk/2|x1−a1|=hk/|1−y1|
={(j+1)(n−j)(n+1)/8}^1/2
n=5のとき
j=0→H0=√15/2
j=1→H1=√6
j=2→H2=3√3/2
j=3→H3=√6
j=4→H4=√15/2
となって,高さの計算には誤りのないことが確認された.やはり,底面積(底体積?)に問題があるのだろう.
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