Returns the Ideal of a Face of a simplicial complex D. Here D is considered as the subcomplex of a simplex on the variables and this ideal defines the stratum of the dual simplex which corresponds to F.
i1 : K=QQ; |
i2 : R=K[x_0..x_4]; |
i3 : I=ideal(x_0*x_1,x_1*x_2,x_2*x_3,x_3*x_4,x_4*x_0); o3 : Ideal of R |
i4 : D=idealToComplex I
o4 = {x x , x x , x x , x x , x x }
2 4 0 3 0 2 1 3 1 4
o4 : complex with 5 facets on the vertices x x x x x
0 1 2 3 4
|
i5 : fc=facets D
o5 = {x x , x x , x x , x x , x x }
2 4 0 3 0 2 1 3 1 4
o5 : List
|
i6 : faceIdeal fc#0
o6 = ideal (x , x , x )
0 1 3
o6 : Ideal of R
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