Difference between revisions of "ApCoCoA-1:BB.ASneighbors"

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<command>
 
<command>
 
   <title>BB.ASneighbors</title>
 
   <title>BB.ASneighbors</title>
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</syntax>
 
</syntax>
 
   <description>
 
   <description>
This command computes the list of across-the-street neighbors in the border of the order ideal <tt>OO</tt>. The input is a list <tt>OO</tt> of terms that specify an order ideal. The output is a list of quadruples <tt>[i,j,k,l]</tt> such that <tt>x_k * b_i = x_l * b_j</tt> where the border terms <tt>b_i</tt> and <tt>b_j</tt> correspond to the <tt>i</tt>-th and <tt>j</tt>-th element of the list returned by the command <ref>BB.Border</ref>(OO).
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This command computes the list of across-the-street neighbors in the border of the order ideal <tt>OO</tt>. The input is a list <tt>OO</tt> of terms that specify an order ideal. The output is a list of quadruples <tt>[i,j,k,l]</tt> such that <tt>x_k * b_i = x_l * b_j</tt> where the border terms <tt>b_i</tt> and <tt>b_j</tt> correspond to the <tt>i</tt>-th and <tt>j</tt>-th element of the list returned by the command <ref>ApCoCoA-1:BB.Border|BB.Border</ref>(OO).
 
<itemize>
 
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   <item>@param <em>OO</em> A list of terms representing an order ideal.</item>
 
   <item>@param <em>OO</em> A list of terms representing an order ideal.</item>
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     <type>borderbasis</type>
 
     <type>borderbasis</type>
 
   </types>
 
   </types>
   <see>BB.NDneighbors</see>
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   <see>ApCoCoA-1:BB.NDneighbors|BB.NDneighbors</see>
 
   <key>ASneighbors</key>
 
   <key>ASneighbors</key>
 
   <key>BB.ASneighbors</key>
 
   <key>BB.ASneighbors</key>
 
   <key>borderbasis.ASneighbors</key>
 
   <key>borderbasis.ASneighbors</key>
   <wiki-category>Package_borderbasis</wiki-category>
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   <wiki-category>ApCoCoA-1:Package_borderbasis</wiki-category>
 
</command>
 
</command>

Latest revision as of 09:38, 7 October 2020

This article is about a function from ApCoCoA-1.

BB.ASneighbors

Computes a list of across-the-street neighbors.

Syntax

BB.ASneighbors(OO:LIST):LIST

Description

This command computes the list of across-the-street neighbors in the border of the order ideal OO. The input is a list OO of terms that specify an order ideal. The output is a list of quadruples [i,j,k,l] such that x_k * b_i = x_l * b_j where the border terms b_i and b_j correspond to the i-th and j-th element of the list returned by the command BB.Border(OO).

  • @param OO A list of terms representing an order ideal.

  • @return A list of across-the-street neighbors of OO.

Example

Use QQ[x,y,z];
BB.Border([1,x]);
BB.ASneighbors([1,x]);

[z, y, xz, xy, x^2]
-------------------------------
[[1, 2, 2, 3], [3, 4, 2, 3], [3, 5, 1, 3], [4, 5, 1, 2]]

-- E.g. the first quadruple of the result can be interpreted
-- as that y*z = z*y

BB.NDneighbors