Test whether a chain complex is exact (except at position 0)
i1 : R = QQ[x_1..x_4,z_1..z_4] o1 = R o1 : PolynomialRing |
i2 : I = ideal(z_2*z_3-z_1*z_4,x_4*z_3-x_3*z_4,x_2*z_2-x_1*z_4,x_4*z_1-x_3*z_2,x_2*z_1-x_1*z_3) o2 = ideal (z z - z z , x z - x z , x z - x z , x z - x z , x z - x z ) 2 3 1 4 4 3 3 4 2 2 1 4 4 1 3 2 2 1 1 3 o2 : Ideal of R |
i3 : cc= res I 1 5 5 1 o3 = R <-- R <-- R <-- R <-- 0 0 1 2 3 4 o3 : ChainComplex |
i4 : isExactRes cc o4 = true |