Let D be an Sn symmetric Q-divisor on M0,n. This function reduces a symmetric divisor D by the gcd of its coefficients in the standard basis. This gives a canonical representative of each nonzero ray in Pic(M0,n)QSn.
i1 : D=symmetricDivisorM0nbar(6,288*B_2+144*B_3)
o1 = 288*B + 144*B
2 3
o1 : S_6-symmetric divisor on M-0-6-bar
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i2 : scale(D)
o2 = 2*B + B
2 3
o2 : S_6-symmetric divisor on M-0-6-bar
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