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D.16.1.6 lowerHomogeneitySpace
Syntax:
lowerHomogeneitySpace( poly g )
lowerHomogeneitySpace( ideal I )
Type:
- cone
Purpose:
- the cone of all weight vectors with non-positive first entry with respect to whom g or I is homogeneous.
Example:
| LIB "gfanlib.so";
ring r = integer,(t,x,y,z),dp;
poly g = tx+t2y;
cone homogSpace = lowerHomogeneitySpace(g);
rays(homogSpace);
==> -2,-1,1,0
generatorsOfLinealitySpace(homogSpace);
==> 0,-1,-1, 0,
==> 0, 0, 0,-1
ideal I = tx+y, t2y+z;
homogSpace = lowerHomogeneitySpace(I);
rays(homogSpace);
==> -3,4,1,-5
generatorsOfLinealitySpace(homogSpace);
==> 0,-1,-1,-1
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