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4.23 cone
In the finite dimensional real vector space R^n, a convex rational polyhedral
cone (in short "cone") is the convex set generated by finitely many half-lines
generated by rational, and hence integer respectively, points. It may or may not
contain a subspace of R^n (e.g. entire lines). The biggest subspace contained in
a cone is called "lineality space". Modulo its lineality space, each cone is
generated by a distinct minimal set of half lines, which are referred to as
"rays". Moreover, a cone can be represented as a set of points satisfying
certain homogeneous linear inequalities and equalities. And these two
characterizations of cones are the two main ways of defining non-trivial cones in
Singular (see coneViaPoints, see coneViaInequalities).
| cone c; // ambient dim 0, no equations,
// no inequalities
cone c = 17; // ambient dim 17, no equations,
// no inequalities
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