Difference between revisions of "ApCoCoA-1:NCo.LWIdeal"

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Latest revision as of 10:21, 7 October 2020

This article is about a function from ApCoCoA-1.

NCo.LWIdeal

Leading word ideal of a finitely generated two-sided ideal in a free monoid ring.

Syntax

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 on <X>. 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 &lt;G&gt; w.r.t. the length-lexicographic word ordering

["yt", "xt", "xy", "xx", "tyy", "yyx"]
-------------------------------

See also

NCo.GB

NCo.LW

NCo.SetOrdering

NCo.SetX

Introduction to CoCoAServer