■基本単体の二面角(その420)
【6】E8格子の場合
P0(0,0,0,0,0,0,0,0)
P1(1,0,0,0,0,0,0,0)
P2(1,1/√3,0,0,0,0,0,0)
P3(1,1/√3,1/√6,0,0,0,0,0)
P4(1,1/√3,1/√6,1/√10,0,0,0,0)
P5(1,1/√3,1/√6,1/√10,1/√15,0,0,0)
P6(1,1/√3,1/√6,1/√10,1/√15,1/√12,0,0)
P7(1,1/√3,1/√6,1/√10,1/√15,1/√12,1/2,0)
P8(1,1/√3,1/√6,1/√10,1/√15,0,0,1/3)
超平面をax+by+cz+dw+ev+fu+gt+is=jとする.
[1]P1P2P3P4P5P6P7P8を通る超平面:x=1
[2]P0P2P3P4P5P6P7P8を通る超平面
j=0
a+b/√3=0,a=1,b=−√3
1−1+c/√6=0,c=0
1−1+c/√6+d/√6=0,d=0,e=0,f=0
g=0,h=0,i=0
[3]P0P1P3P4P5P6P7P8を通る超平面
j=0,a=0
b/√3+c/√6=0,b=1,c=−√2
b/√3+c/√6+d/√6=0,d=0,e=0,f=0
g=0,h=0,i=0
[4]P0P1P2P4P5P6P7P8を通る超平面
j=0,a=0,b=0
c/√6+d/√10=0,c=√3,d=−√5
e=0,f=0,g=0,h=0,i=0
[5]P0P1P2P3P5P6P7P8を通る超平面
j=0,a=0,b=0,c=0
d/√10+e/√15=0,d=√2,e=−√3
f=0,g=0,h=0,i=0
[6]P0P1P2P3P4P6P7P8を通る超平面
j=0,a=0,b=0,c=0,d=0
e/√15+f/√12=0,e=√5,f=−2
g=0,h=0
e/√15+i/3=0,i=−3e/√15=−√3
[7]P0P1P2P3P4P5P7P8を通る超平面
j=0,a=0,b=0,c=0,d=0,e=0
f/√12+g/2=0,f=√3,g=−1
h=0,i=0
[8]P0P1P2P3P4P5P6P8を通る超平面:t=0
[9]P0P1P2P3P4P5P6P7を通る超平面:s=0
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a=(1,0,0,0,0,0,0,0)
b=(1,−√3,0,0,0,0,0,0)
c=(0,1,−√2,0,0,0,0,0)
d=(0,0,√3,−√5,0,0,0,0)
e=(0,0,0,√2,−√3,0,0,0)
f=(0,0,0,0,√5,−2,0,−√3)
g=(0,0,0,0,0,√3,−1,0)
h=(0,0,0,0,0,0,1,0)
i=(0,0,0,0,0,0,0,1)
を正規化すると
a=(1,0,0,0,0,0,0,0)
b=(1/2,−√3/2,0,0,0,0,0,0)
c=(0,1/√3,−√(2/3),0,0,0,0,0)
d=(0,0,√(3/8),−√(5/8),0,0,0,0)
e=(0,0,0,√(2/5),−√(3/5),0,0,0)
f=(0,0,0,0,√(5/12),−1/√3,0,−1/2)
g=(0,0,0,0,0,√3/2,−1/2,0)
h=(0,0,0,0,0,0,1,0)
i=(0,0,0,0,0,0,0,1)
a・b=1/2
b・c=−1/2
c・d=−1/2
d・e=−1/2
d・h=−1/2
e・f=−1/2
f・g=−1/2
f・i=−1/2
g・h=−1/2
h・i=0
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[まとめ]以上により,無限鏡映群の基本単体は有限鏡映群の二面角を変えずに辺の長さを変えたものであることが確かめられた.
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