e> of the first element of the left descent set of  <code>w</code> ‚Äì- that is, the first  <code>i</code> such that if <code>s=W(i)</code> then <code>l(sw)&lt;l(w). It returns</code>nothing<code>for</code>one(W)`.</p><pre><code class="language-julia-repl hljs">julia&gt; W=coxsym(3)
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julia&gt; firstleftdescent(W,Perm(2,3))
2</code></pre></div><a class="docs-sourcelink" target="_blank" href="https://github.com/jmichel7/Chevie.jl/blob/fbddb048572eb9b42fb2c8f80113717339b328da/src/CoxGroup