colon -- colon of a (truncated) dual space

Synopsis

Usage:

Dg = colon(D,g)

DJ = colon(D,J)
Inputs:
- D, an instance of the type DualSpace
- g, a ring element
- J, an ideal
Optional inputs:
- Tolerance => ..., default value .000001
Outputs:
- an instance of the type DualSpace, Dg, DJ

This computes (a part of) the dual space of the dual. See

R. Krone and A. Leykin, "Numerical algorithms for detecting embedded components.", arXiv:1405.7871

for a description.