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maxMinors -- computes the ideal generated by the maximal non-vanishing minors of a given matrix

Synopsis

Description

Let I_t(M) be the ideal in R generated by the t \times\ t minors of M. If there exists an r such that I_r(M) is non-zero and I_{r+1}(\phi) = 0, then maxMinors M gives I_r(M). 
i1 : R = QQ[x,y]

o1 = R

o1 : PolynomialRing
 
i2 : M = matrix{{x,0},{-y,x},{0,-y}}

o2 = | x  0  |
     | -y x  |
     | 0  -y |

             3      2
o2 : Matrix R  <-- R
 
i3 : maxMinors M

             2         2
o3 = ideal (x , -x*y, y )

o3 : Ideal of R

This method returns the unit ideal as the ideal of maximal minors of the zero matrix. 
i4 : N = matrix{{0_R}}

o4 = 0

             1      1
o4 : Matrix R  <-- R
 
i5 : maxMinors N

o5 = ideal 1

o5 : Ideal of R

See also

Ways to use maxMinors :

For the programmer

The object maxMinors is a method function.