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<a accesskey="1" href="page.php?w=relation_algebra&amp;p=4">1.Previous</a><br />
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<p>Roughly, a relation algebra is to a system of binary relations on a set containing the <a href="page.php?w=empty_relation">empty</a> (), <a href="page.php?w=universal_relation">universal</a> (), and <a href="page.php?w=identity_relation">identity</a>  relations and closed under these five operations as a <a href="page.php?w=group_%28mathematics%29">group</a> is to a system of <a href="page.php?w=permutation">permutation</a>s of a set containing the <a href="page.php?w=identity_function">identity permutation</a> and closed under <a href="page.php?w=function_composition">composition</a></p><p>
<a accesskey="1" href="page.php?w=relation_algebra&amp;p=4">1.Previous</a><br />
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