next | previous | forward | backward | up | top | index | toc | Macaulay2 web site
Macaulay2Doc :: gbRemove

gbRemove -- remove Gröbner basis

Synopsis

Description

This is a simple way to remove the space associated with large Gröbner bases that are no longer needed.
i1 : R = ZZ[a]/(a^2-3)[x,y]

o1 = R

o1 : PolynomialRing
i2 : F = y^2-x*(x-1)*(x-a)

        3           2    2
o2 = - x  + (a + 1)x  + y  - a*x

o2 : R
i3 : J = ideal(diff(x,F),diff(y,F),F)

                2                         3           2    2
o3 = ideal (- 3x  + (2a + 2)x - a, 2y, - x  + (a + 1)x  + y  - a*x)

o3 : Ideal of R
i4 : gens gb J

o4 = | 12 6a+6 2y 4x-2a+6 (2a+2)x+2a+6 y2+2x-a-3 x2+3a |

             1       7
o4 : Matrix R  <--- R
i5 : peek J.generators.cache

o5 = CacheTable{GroebnerBasisOptions{HardDegreeLimit => null} => GroebnerBasis[status: done; S-pairs encountered up to degree 8]}
                                     Syzygies => false
                                     SyzygyRows => 0
                image => image | -3x2+(2a+2)x-a 2y -x3+(a+1)x2+y2-ax |
                isHomogeneous => false
i6 : gbRemove J
i7 : peek J.generators.cache

o7 = CacheTable{image => image | -3x2+(2a+2)x-a 2y -x3+(a+1)x2+y2-ax |}
                isHomogeneous => false

See also

Ways to use gbRemove :