<?xml version="1.0" encoding="utf-8" ?> <!-- for emacs: -*- coding: utf-8 -*- -->
<!-- Apache may like this line in the file .htaccess: AddCharset utf-8 .html -->
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1 plus MathML 2.0 plus SVG 1.1//EN" "http://www.w3.org/2002/04/xhtml-math-svg/xhtml-math-svg-flat.dtd" >
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head><title>selectVariables(List,PolynomialRing) -- make a subring of a polynomial ring generated by selected variables</title>
<link rel="stylesheet" type="text/css" href="../../../../Macaulay2/Style/doc.css"/>
</head>
<body>
<table class="buttons">
<tr>
<td><div><a href="___Self__Initializing__Type.html">next</a> | <a href="_select__In__Subring.html">previous</a> | <a href="___Self__Initializing__Type.html">forward</a> | <a href="_select__In__Subring.html">backward</a> | up | <a href="index.html">top</a> | <a href="master.html">index</a> | <a href="toc.html">toc</a> | <a href="http://www.math.uiuc.edu/Macaulay2/">Macaulay2 web site</a></div>
</td>
</tr>
</table>
<hr/>
<div><h1>selectVariables(List,PolynomialRing) -- make a subring of a polynomial ring generated by selected variables</h1>
<div class="single"><h2>Synopsis</h2>
<ul><li><div class="list"><dl class="element"><dt class="heading">Usage: </dt><dd class="value"><div><tt>(S,f) = selectVariables(v,R)</tt></div>
</dd></dl>
</div>
</li>
<li><span>Function: <a href="_select__Variables_lp__List_cm__Polynomial__Ring_rp.html" title="make a subring of a polynomial ring generated by selected variables">selectVariables</a></span></li>
<li><div class="single">Inputs:<ul><li><span><tt>v</tt>, <span>a <a href="___List.html">list</a></span>, a sorted list of numbers specifying which variables to select</span></li>
<li><span><tt>R</tt>, <span>a <a href="___Polynomial__Ring.html">polynomial ring</a></span></span></li>
</ul>
</div>
</li>
<li><div class="single">Outputs:<ul><li><span><tt>S</tt>, <span>a <a href="___Polynomial__Ring.html">polynomial ring</a></span>, a polynomial ring generated as a subring of R by the variables whose indices occur in the list v, together with the induced monomial ordering</span></li>
<li><span><tt>f</tt>, <span>a <a href="___Ring__Map.html">ring map</a></span>, the inclusion map from S to R</span></li>
</ul>
</div>
</li>
</ul>
</div>
<div class="single"><h2>Description</h2>
<div><table class="examples"><tr><td><pre>i1 : (S,f) = selectVariables({2,4}, QQ[a..h,Weights=>1..8]);</pre>
</td></tr>
<tr><td><pre>i2 : describe S
o2 = QQ[c, e, Degrees => {2:1}, Heft => {1}, MonomialOrder => {MonomialSize => 32}, DegreeRank => 1]
{Weights => {3, 5} }
{GRevLex => {2:1} }
{Position => Up }</pre>
</td></tr>
<tr><td><pre>i3 : options S
o3 = OptionTable{DegreeLift => null }
DegreeMap => null
DegreeRank => 1
Degrees => {{1}, {1}}
Global => true
Heft => {1}
Inverses => false
Join => null
Local => false
MonomialOrder => {MonomialSize => 32}
{Weights => {3, 5} }
{GRevLex => {1, 1} }
{Position => Up }
SkewCommutative => {}
Variables => {c, e}
WeylAlgebra => {}
o3 : OptionTable</pre>
</td></tr>
<tr><td><pre>i4 : f
o4 = map(QQ[a, b, c, d, e, f, g, h],S,{c, e})
o4 : RingMap QQ[a, b, c, d, e, f, g, h] <--- S</pre>
</td></tr>
</table>
</div>
</div>
</div>
</body>
</html>
