Difference between revisions of "ApCoCoA-1:NC.IsGB"

From ApCoCoAWiki
m (replaced <quotes> tag by real quotes)
 
(52 intermediate revisions by 9 users not shown)
Line 1: Line 1:
 +
{{Version|1}}
 
<command>
 
<command>
 
<title>NC.IsGB</title>
 
<title>NC.IsGB</title>
 
<short_description>
 
<short_description>
−
Check if a list of polynomials if Groebner basis.
+
Check whether a LIST of non-zero polynomials is a Groebner basis in a non-commutative polynomial ring.  
 
</short_description>
 
</short_description>
 
<syntax>
 
<syntax>
−
NC.IsGB(Polynomials:LIST):BOOL
+
NC.IsGB(G:LIST):BOOL
 
</syntax>
 
</syntax>
 
<description>
 
<description>
 +
Note that, given a word ordering, a set of non-zero polynomials <tt>G</tt> is called a <em>Groebner basis</em> of with respect to this ordering if the leading word set <tt>LW{G}</tt> generates the leading word ideal <tt>LW(&lt;G&gt;)</tt>. This function checks whether a given finite set of non-zero polynomial <tt>G</tt> is a Groebner basis by using the <tt>Buchberger Criterion</tt>, i.e. <tt>G</tt> is a Groebner basis if the S-polynomials of all obstructions of <tt>G</tt> have the zero normal remainder with respect to <tt>G</tt>.
 +
<par/>
 
<em>Please note:</em> The function(s) explained on this page is/are using the <em>ApCoCoAServer</em>. You will have to start the ApCoCoAServer in order to use it/them.
 
<em>Please note:</em> The function(s) explained on this page is/are using the <em>ApCoCoAServer</em>. You will have to start the ApCoCoAServer in order to use it/them.
 +
<par/>
 +
Please set non-commutative polynomial ring (via the command <ref>ApCoCoA-1:Use|Use</ref>) and word ordering (via the function <ref>ApCoCoA-1:NC.SetOrdering|NC.SetOrdering</ref>) before calling this function. The default word ordering is the length-lexicographic ordering ("LLEX"). For more information, please check the relevant commands and functions.
 
<itemize>
 
<itemize>
−
<item>Before calling the function, please set ring environment coefficient field (<tt>K</tt>), alphabet (<tt>X</tt>) and ordering through the functions NC.SetFp(Prime) (or NC.UnsetFp()), NC.SetX(X) and NC.SetOrdering(Ordering) respectively. Default coefficient field is <tt>Q</tt>. Default ordering is length-lexicographic ordering (<quotes>LLEX</quotes>). For more information, please check the relevant functions.</item>
+
<item>@param <em>G</em>: a LIST of non-zero non-commutative polynomials. Each polynomial is represented as a LIST of LISTs, and each element in every inner LIST involves only one indeterminate or none (a constant). For example, the polynomial <tt>f=2x[2]y[1]x[2]^2-9y[2]x[1]^2x[2]^3+5</tt> is represented as F:=[[2x[1],y[1],x[2]^2], [-9y[2],x[1]^2,x[2]^3], [5]]. The zero polynomial <tt>0</tt> is represented as the empty LIST [].</item>
−
<item>@param <em>Polynomials</em>: a LIST of polynomials in <tt>K&lt;X&gt;</tt>. Each polynomial in <tt>K&lt;X&gt;</tt> is represented as a LIST of LISTs, which are pairs of form <tt>[c, w]</tt> where <tt>c</tt> is in <tt>K</tt> and <tt>w</tt> is a word in <tt>X*</tt>.  Unit in <tt>X*</tt> is empty word represented as an empty STRING <quotes></quotes>. 0 polynomial is represented as an empty LIST <tt>[]</tt>. For example, polynomial <tt>F:=xy-y+1</tt> in <tt>K&lt;x,y&gt;</tt> is represented as <tt>F:=[[1,<quotes>xy</quotes>], [-1, <quotes>y</quotes>], [1,<quotes></quotes>]]</tt>.</item>
+
<item>@return: a BOOL, which is True if <tt>G</tt> is a Groebner basis with respect to the current ordering and False otherwise.</item>
−
<item>@return: a BOOL value. True if <tt>Polynomials</tt> is a GB; False, otherwise.</item>
 
 
</itemize>
 
</itemize>
 
<example>
 
<example>
−
NC.SetX(<quotes>xyt</quotes>);
+
Use ZZ/(2)[t,x,y];
−
NC.SetOrdering(<quotes>LLEX</quotes>);  
+
G := [[[x^2], [y, x]], [[t, y], [x, y]], [[y, t], [x, y]], [[t, x], [x, t]],
−
F1 := [[1,<quotes>xx</quotes>], [-1,<quotes>yx</quotes>]]; 
+
[[x, y, x], [y^2, x]], [[x, y^2], [y, x, y]], [[y, x, t], [y^2, x]]];
−
F2 := [[1,<quotes>xy</quotes>], [-1,<quotes>ty</quotes>]]; 
+
NC.SetOrdering("ELIM");  
−
F3 := [[1,<quotes>xt</quotes>], [-1, <quotes>tx</quotes>]]; 
+
NC.IsGB(G);
−
F4 := [[1,<quotes>yt</quotes>], [-1, <quotes>ty</quotes>]]; 
+
 
−
Polynomials := [F1, F2,F3,F4];  
+
True
−
NC.IsGB(Polynomials);
 
−
False
 
 
-------------------------------
 
-------------------------------
−
NC.SetOrdering(<quotes>ELIM</quotes>);
+
NC.SetOrdering("LLEX");  
−
NC.IsGB(Polynomials);
+
NC.IsGB(G);
 +
 
 
False
 
False
 
-------------------------------
 
-------------------------------
Line 32: Line 35:
 
</description>
 
</description>
 
<seealso>
 
<seealso>
−
<see>NC.Add</see>
+
<see>ApCoCoA-1:Use|Use</see>
−
<see>NC.GB</see>
+
<see>ApCoCoA-1:NC.GB|NC.GB</see>
−
<see>NC.LT</see>
+
<see>ApCoCoA-1:NC.LW|NC.LW</see>
−
<see>NC.Multiply</see>
+
<see>ApCoCoA-1:NC.RedGB|NC.RedGB</see>
−
<see>NC.NR</see>
+
<see>ApCoCoA-1:NC.SetOrdering|NC.SetOrdering</see>
−
<see>NC.Subtract</see>
+
<see>ApCoCoA-1:NC.TruncatedGB|NC.TruncatedGB</see>
−
<see>Gbmr.MRSubtract</see>
+
<see>ApCoCoA-1:Introduction to CoCoAServer|Introduction to CoCoAServer</see>
−
<see>Gbmr.MRMultiply</see>
 
−
<see>Gbmr.MRBP</see>
 
−
<see>Gbmr.MRIntersection</see>
 
−
<see>Gbmr.MRKernelOfHomomorphism</see>
 
−
<see>Gbmr.MRMinimalPolynomials</see>
 
−
<see>Introduction to CoCoAServer</see>
 
 
</seealso>
 
</seealso>
 
<types>
 
<types>
 
<type>apcocoaserver</type>
 
<type>apcocoaserver</type>
 +
<type>ideal</type>
 
<type>groebner</type>
 
<type>groebner</type>
 +
<type>non_commutative</type>
 
</types>
 
</types>
 +
<key>ncpoly.IsGB</key>
 
<key>NC.IsGB</key>
 
<key>NC.IsGB</key>
 
<key>IsGB</key>
 
<key>IsGB</key>
−
<wiki-category>Package_gbmr</wiki-category>
+
<wiki-category>ApCoCoA-1:Package_ncpoly</wiki-category>
 
</command>
 
</command>

Latest revision as of 13:34, 29 October 2020

This article is about a function from ApCoCoA-1.

NC.IsGB

Check whether a LIST of non-zero polynomials is a Groebner basis in a non-commutative polynomial ring.

Syntax

NC.IsGB(G:LIST):BOOL

Description

Note that, given a word ordering, a set of non-zero polynomials G is called a Groebner basis of with respect to this ordering if the leading word set LW{G} generates the leading word ideal LW(<G>). This function checks whether a given finite set of non-zero polynomial G is a Groebner basis by using the Buchberger Criterion, i.e. G is a Groebner basis if the S-polynomials of all obstructions of G have the zero normal remainder with respect to G.

Please note: The function(s) explained on this page is/are using the ApCoCoAServer. You will have to start the ApCoCoAServer in order to use it/them.

Please set non-commutative polynomial ring (via the command Use) and word ordering (via the function NC.SetOrdering) before calling this function. The default word ordering is the length-lexicographic ordering ("LLEX"). For more information, please check the relevant commands and functions.

  • @param G: a LIST of non-zero non-commutative polynomials. Each polynomial is represented as a LIST of LISTs, and each element in every inner LIST involves only one indeterminate or none (a constant). For example, the polynomial f=2x[2]y[1]x[2]^2-9y[2]x[1]^2x[2]^3+5 is represented as F:=[[2x[1],y[1],x[2]^2], [-9y[2],x[1]^2,x[2]^3], [5]]. The zero polynomial 0 is represented as the empty LIST [].

  • @return: a BOOL, which is True if G is a Groebner basis with respect to the current ordering and False otherwise.

Example

Use ZZ/(2)[t,x,y];
G := [[[x^2], [y, x]], [[t, y], [x, y]], [[y, t], [x, y]], [[t, x], [x, t]], 
[[x, y, x], [y^2, x]], [[x, y^2], [y, x, y]], [[y, x, t], [y^2, x]]];
NC.SetOrdering("ELIM"); 
NC.IsGB(G);

True
-------------------------------
NC.SetOrdering("LLEX"); 
NC.IsGB(G);

False
-------------------------------

See also

Use

NC.GB

NC.LW

NC.RedGB

NC.SetOrdering

NC.TruncatedGB

Introduction to CoCoAServer




Retrieved from "http://apcocoa.uni-passau.de/wiki/index.php?title=ApCoCoA-1:NC.IsGB&oldid=16094"