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<li><p><span class="math notranslate nohighlight">\(L^2\)</span> function is a function <span class="math notranslate nohighlight">\(f: X \to \mathbb{R}\)</span> that is square integrable: <span class="math notranslate nohighlight">\(|f|^2 = \int_X |f|^2 d\mu\)</span> with respect to the measure <span class="math notranslate nohighlight">\(\mu\)</span></p>
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<li><p><span class="math notranslate nohighlight">\(|f|\)</span> is its <span class="math notranslate nohighlight">\(L^2\)</span>-norm</p></li>
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