The hyperplane arrangement with hyperplanes x_i-x_j.
i1 : A3 = typeA(3)
o1 = A3
o1 : Hyperplane Arrangement
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i2 : describe A3
o2 = {x - x , x - x , x - x , x - x , x - x , x - x }
1 2 1 3 1 4 2 3 2 4 3 4
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i3 : ring A3
o3 = QQ [x , x , x , x ]
1 2 3 4
o3 : PolynomialRing
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Alternatively, one may specify a coordinate ring,
i4 : S = ZZ[w,x,y,z];
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i5 : A3' = typeA(3,S)
o5 = A3'
o5 : Hyperplane Arrangement
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i6 : describe A3'
o6 = {w - x, w - y, w - z, x - y, x - z, y - z}
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or a coefficient ring:
i7 : A4 = typeA(4,ZZ/3)
o7 = A4
o7 : Hyperplane Arrangement
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i8 : ring A4
ZZ
o8 = -- [x , x , x , x , x ]
3 1 2 3 4 5
o8 : PolynomialRing
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