https://jaalonso.github.io/calculemus/esContents © 2026 <a href="mailto:">José A. Alonso</a> <a rel="license" href="https://creativecommons.org/licenses/by-nc-sa/4.0/"> <img alt="Creative Commons License BY-NC-SA" style="border-width:0; margin-bottom:12px;" src="https://i.creativecommons.org/l/by-nc-sa/4.0/88x31.png"></a>Sun, 18 Oct 2026 17:46:51 GMTNikola (getnikola.com)http://blogs.law.harvard.edu/tech/rsshttps://jaalonso.github.io/calculemus/posts/2026/08/03-desigualdad_triangular_inversa/José A. Alonso<div><p>Demostrar la desigualdad triangular inversa; es decir, que para cualesquiera números reales \(x\) e \(y\), se cumple la siguiente relación: \[ ||x| - |y|| ≤ |x - y| \]</p> <p>Para ello, completar la siguiente teoría de Lean 4:</p> <div class="code"><pre class="code literal-block"><span class="kn">import</span><span class="w"> </span><span class="n">Mathlib.Data.Real.Basic</span> <span class="kn">import</span><span class="w"> </span><span class="n">Mathlib.Tactic</span> <span class="kd">variable</span><span class="w"> </span><span class="o">(</span><span class="n">x</span><span class="w"> </span><span class="n">y</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">ℝ</span><span class="o">)</span> <span class="kd">example</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="bp">|</span><span class="o">(</span><span class="bp">|</span><span class="n">x</span><span class="bp">|</span><span class="w"> </span><span class="bp">-</span><span class="w"> </span><span class="bp">|</span><span class="n">y</span><span class="bp">|</span><span class="o">)</span><span class="bp">|</span><span class="w"> </span><span class="bp">≤</span><span class="w"> </span><span class="bp">|</span><span class="n">x</span><span class="w"> </span><span class="bp">-</span><span class="w"> </span><span class="n">y</span><span class="bp">|</span><span class="w"> </span><span class="o">:=</span> <span class="kd">by</span><span class="w"> </span><span class="gr">sorry</span> </pre></div> <hr> <p><a href="https://jaalonso.github.io/calculemus/posts/2026/08/03-desigualdad_triangular_inversa/">Leer más…</a> (quedan 4 minutos de lectura)</p></div>AnálisisLean4Números realesRetoLean4https://jaalonso.github.io/calculemus/posts/2026/08/03-desigualdad_triangular_inversa/Mon, 03 Aug 2026 04:00:00 GMT