■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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