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<head><title>posetJoin -- returns the join of two elements</title>
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<div><h1>posetJoin -- returns the join of two elements</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>j = posetJoin (P,a,b)</tt></div>
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<li><div class="single">Inputs:<ul><li><span><tt>P</tt>, <span>an object of class <a href="___Poset.html" title="a class for partially ordered sets (posets)">Poset</a></span></span></li>
<li><span><tt>a</tt>, <span>a <a href="../../Macaulay2Doc/html/___Thing.html">thing</a></span></span></li>
<li><span><tt>b</tt>, <span>a <a href="../../Macaulay2Doc/html/___Thing.html">thing</a></span>, a and b are in P</span></li>
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<li><div class="single">Outputs:<ul><li><span><tt>j</tt>, <span>a <a href="../../Macaulay2Doc/html/___Thing.html">thing</a></span>, j is the join of a and b in P</span></li>
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<div class="single"><h2>Description</h2>
<div><div>This function returns the least element that is greater than both a and b in P.</div>
<table class="examples"><tr><td><pre>i1 : P = poset ({a,b,c,d,e,f}, {(a,d),(d,f),(b,d),(b,e),(c,e),(e,f)});</pre>
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<tr><td><pre>i2 : posetJoin (P, a,b)
o2 = {d}
o2 : List</pre>
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<div class="single"><h2>Caveat</h2>
<div><div>This function returns an error if the join does not exist. To check if the join exists use joinExists.</div>
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<div class="single"><h2>See also</h2>
<ul><li><span><a href="_join__Exists.html" title="determines if the join exists">joinExists</a> -- determines if the join exists</span></li>
<li><span><a href="_poset__Meet.html" title="returns the meet of two elements">posetMeet</a> -- returns the meet of two elements</span></li>
<li><span><a href="_meet__Exists.html" title="determines if the meet exists">meetExists</a> -- determines if the meet exists</span></li>
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<div class="waystouse"><h2>Ways to use <tt>posetJoin</tt> :</h2>
<ul><li>posetJoin(Poset,Thing,Thing)</li>
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