singularLocus(MultiprojectiveVariety) -- the singular locus of the variety

Synopsis

Function: singularLocus
Usage:

singularLocus X
Inputs:
- X, a multi-projective variety, which is assumed to be equidimensional
Outputs:
- a multi-projective variety, the singular locus of $X$

Description

i1 : X = random({2,1},point PP_(ZZ/101)^{2,1});

o1 : ProjectiveVariety, surface in PP^2 x PP^1

i2 : singularLocus X

o2 = empty subscheme of PP^2 x PP^1

o2 : ProjectiveVariety, empty subscheme of PP^2 x PP^1

i3 : Y = X + random({1,1},0_X);

o3 : ProjectiveVariety, surface in PP^2 x PP^1

i4 : singularLocus Y

o4 = curve in PP^2 x PP^1 cut out by 3 hypersurfaces of multi-degrees (1,1)^1 (2,1)^1 (3,0)^1 

o4 : ProjectiveVariety, curve in PP^2 x PP^1