ApCoCoA-1:NCo.LWIdeal
From ApCoCoAWiki
NC.LTIdeal
Leading word ideal of a finitely generated two-sided ideal in a free monoid ring.
Description
Proposition: Let I be a finitely generated two-sided ideal in a free monoid ring K<X>, and let Ordering be a word ordering. If G is a Groebner basis of I with respect to Ordering. Then the leading word set LW{G}:={LW(g): g in G} is a generating system of the leading word ideal LW(I) with respect to Ordering.
Example
NCo.SetX("xyzt");
NCo.SetOrdering("LLEX");
F1 := [[1,"xx"], [-1,"yx"]];
F2 := [[1,"xy"], [-1,"ty"]];
F3 := [[1,"xt"], [-1,"tx"]];
F4 := [[1,"yt"], [-1,"ty"]];
G := [F1,F2,F3,F4];
GB:=NCo.GB(G);
[NCo.LW(E) | E In GB]; -- the leading word ideal of <G>
["yt", "xt", "xy", "xx", "tyy", "yyx"]
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See also
