 This object arises when we study cones in formula_23 together with the lattice formula_24.A cone is called rational (here we assume "pointed", as defined above) whenever its generators all have integer coordinates, i.e., if formula_10 is a rational cone, then formula_26.Let "C" ⊂ "V" be a set, not necessary a convex set, in a real vector space "V" equipped with an inner product.