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Reference.org
Unit interval
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<p>In <a href="/facts/Mathematics/pxTouaz4">mathematics</a>, the unit interval is the <a href="/facts/Interval_(mathematics)/e9se3vTe">closed interval</a> [0,1], that is, the <a href="/facts/Set_(mathematics)/BfucfHMq">set</a> of all <a href="/facts/Real_number/R02gw5Pb">real numbers</a> that are greater than or equal to 0 and less than or equal to 1. It is often denoted <i>I</i> (capital letter I). In addition to its role in <a href="/facts/Real_analysis/12WjlXCW">real analysis</a>, the unit interval is used to study <a href="/facts/Homotopy_theory/MJwYyRny">homotopy theory</a> in the field of <a href="/facts/Topology/2EqW47cU">topology</a>. </p><p>In the literature, the term "unit interval" is sometimes applied to the other shapes that an interval from 0 to 1 could take: (0,1], [0,1), and (0,1). However, the notation <i>I</i> is most commonly reserved for the closed interval [0,1]. </p>