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<head><title>parent -- parent type of an object</title>
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<div><a href="index.html" title="">Macaulay2Doc</a> > <a href="___The_sp__Macaulay2_splanguage.html" title="">The Macaulay2 language</a> > <a href="_what_spa_spclass_spis.html" title="">what a class is</a> > <a href="_parent.html" title="parent type of an object">parent</a></div>
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<div><h1>parent -- parent type of an object</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>X = parent x</tt></div>
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<li><div class="single">Inputs:<ul><li><span><tt>x</tt></span></li>
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<li><div class="single">Outputs:<ul><li><span><tt>X</tt>, <span>a <a href="___Type.html">type</a></span>, the parent class of <tt>x</tt></span></li>
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<div class="single"><h2>Description</h2>
<div>Methods for the instances of <tt>X</tt> which are not found in <tt>X</tt> itself are sought in <tt>P</tt>, and its parent, and so on. Thus the mathematical notion of a set <tt>P</tt> and a subset <tt>X</tt> can modeled in this way.<p/>
Things that don't have instances have the empty class, called <a href="___Nothing.html" title="the empty class">Nothing</a> as their parent. The parent of <a href="___Thing.html" title="the class of all things">Thing</a> is <a href="___Thing.html" title="the class of all things">Thing</a> itself (because every thing is a thing).<p/>
The entire structure of types and their parents can be displayed with <a href="_show__Structure.html" title="display parent structure">showStructure</a>.</div>
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