Singular Manual: lpHilbert

| #### 7.10.1.5 lpHilbert Procedure from library `fpadim.lib` (see fpadim_lib). Usage: lpHilbert(G[,degbound,n]); G an ideal, degbound, n optional integers Return: intvec, containing the coefficients of the Hilbert series Purpose: Compute the truncated Hilbert series of K<X>/<G> up to a degree bound Assume: - basering is a Letterplace ring. - if you specify a different degree bound degbound, degbound <= attrib(basering,uptodeg) holds. Theory: Hilbert series of an algebra K<X>/<G> is sum_(i>=0) h_i t^i, where h_i is the K-dimension of the space of monomials of degree i, not contained in <G>. For finitely presented algebras Hilbert series NEED NOT be a rational function, though it happens often. Therefore in general there is no notion of a Hilbert polynomial. Note: - If degbound is set, there will be a degree bound added. 0 means no degree bound. Default: attrib(basering,uptodeg). - n is the number of variables, which can be set to a different number. Default: attrib(basering, lV). - In the output intvec I, I[k] is the (k-1)-th coefficient of the Hilbert series, i.e. h_(k-1) as above. Example:
    LIB "fpadim.lib";
    ring r = 0,(x,y),dp;
    def R = freeAlgebra(r, 5); // constructs a Letterplace ring
    setring R; // sets basering to Letterplace ring
    ideal G = y*y,x*y*x; // G is a Groebner basis
    lpHilbert(G); // procedure with default parameters
    ==> 1,2,3,4,4,4
    lpHilbert(G,3,2); // invokes procedure with degree bound 3 and (same) 2 variables
    ==> 1,2,3,4
See also: ncHilb_lib.

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