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Add presentation slides for OU process and Mehler formula
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<div class="hintkey">← → 翻页 · F 全屏 · 刷新记忆当前页</div>
<div id="wrap">
<div class="stage" id="stage">
<!-- 1 封面 -->
<section class="slide active cover">
<div class="glow"></div>
<div class="kicker"><span class="ln"></span>SELF-SUPERVISED · 谱分解 · EP.01</div>
<h1 style="margin-top:34px;">Hermite<br><em>多项式</em></h1>
<p class="lead" style="margin-top:38px;">高斯世界里的「频率分解」工具<br>—— 配套播客讲解,从直觉到 LeJEPA 的理论基石</p>
<div class="meta">配套音频 7:43 · 双主播对话 · 数学不可怕,可怕的是没人陪你拆积木</div>
</section>
<!-- 2 动机 -->
<section class="slide posBL">
<div class="glow amber"></div>
<div class="kicker"><span class="ln"></span>01 · 动机</div>
<h2>我们需要一把<em>拆函数的刀</em></h2>
<div class="content">
<ul class="pts">
<li>LeJEPA 的证明要回答:编码器的表示里,<b>哪一部分</b>对「正样本对」的相关性贡献最大?</li>
<li>正样本对 = 同一内容的两个视角,模型希望它们的表示尽量像。</li>
<li>要回答这个问题,得先能把<b>任意函数拆成一块块</b>——就像傅里叶把声音拆成不同频率的波。</li>
<li>在高斯(钟形)分布下,这套「积木」就是 <b>Hermite 多项式</b></li>
</ul>
</div>
</section>
<!-- 3 傅里叶类比 -->
<section class="slide">
<div class="glow"></div>
<div class="kicker"><span class="ln"></span>02 · 类比</div>
<h2>傅里叶之于周期,<em>Hermite</em> 之于高斯</h2>
<div class="content">
<table class="cmp">
<tr><th>维度</th><th>傅里叶级数</th><th>Hermite 展开</th></tr>
<tr><td class="k">适用场景</td><td><span class="fr">周期函数</span></td><td><span class="he">高斯分布下的函数</span></td></tr>
<tr><td class="k">基函数</td><td><span class="fr">$\sin nx,\ \cos nx$</span></td><td><span class="he">$He_0,He_1,He_2,\dots$</span></td></tr>
<tr><td class="k">正交性</td><td><span class="fr">在区间上积分为 0</span></td><td><span class="he">在高斯期望下为 0</span></td></tr>
<tr><td class="k">完备性</td><td><span class="fr">任意周期函数可展开</span></td><td><span class="he">任意 $L^2(\gamma)$ 函数可展开</span></td></tr>
</table>
</div>
</section>
<!-- 4 定义与递推 -->
<section class="slide posCR">
<div class="glow"></div>
<div class="kicker"><span class="ln"></span>03 · 定义</div>
<h2>积木长什么样 & <em>递推</em>搭出来</h2>
<div class="content" style="gap:60px;">
<div class="fbox" style="flex:1;font-size:34px;line-height:2;">
$He_0=1,\quad He_1=z$<br>
$He_2=z^2-1$<br>
$He_3=z^3-3z$<br>
$He_4=z^4-6z^2+3$
</div>
<div style="flex:1;">
<div class="fbox" style="font-size:40px;">
$He_{n+1}(z)=z\,He_n(z)-n\,He_{n-1}(z)$
<div class="small">下一块 = z × 当前块 − 阶数 × 前一块</div>
</div>
<p class="lead" style="margin-top:30px;font-size:26px;">验证:$z\cdot z-1\cdot 1=z^2-1=He_2$ ✓</p>
</div>
</div>
</section>
<!-- 5 正交性 -->
<section class="slide">
<div class="glow amber"></div>
<div class="kicker"><span class="ln"></span>04 · 核心性质</div>
<h2>正交性:不同阶数<em>互不干扰</em></h2>
<div class="content" style="gap:60px;">
<div class="fbox" style="flex:1.1;font-size:34px;">
$\mathbb{E}\big[He_m(z)\,He_n(z)\big]=\begin{cases}n! & m=n\\[4pt]0 & m\neq n\end{cases}$
<div class="small">$z\sim\mathcal N(0,1)$,期望对钟形曲线取</div>
</div>
<div style="flex:1;">
<div class="card">
<div class="ct">最小例子验证</div>
<div class="cb" style="font-size:28px;line-height:1.8;">
$\mathbb{E}[He_1\cdot He_2]=\mathbb{E}[z^3-z]$<br>
高斯的奇数阶矩为 0 → $=0-0=0$ ✓
</div>
<div class="cf" style="font-size:26px;">就像不同频率的正弦波互相正交</div>
</div>
</div>
</div>
</section>
<!-- 6 完备性 -->
<section class="slide posBL">
<div class="glow"></div>
<div class="kicker"><span class="ln"></span>05 · 完备性</div>
<h2>任意函数都能<em>拆开重组</em></h2>
<div class="content" style="gap:60px;">
<div class="fbox" style="flex:1;font-size:36px;">
$h(z)=\sum_{d=0}^{\infty}c_d\,He_d(z)$
<div class="small">$c_d=\dfrac{\mathbb{E}[h(z)\,He_d(z)]}{d!}$</div>
</div>
<div style="flex:1;">
<p class="lead" style="font-size:30px;">只要 $\mathbb{E}[h(z)^2]<\infty$(有限能量),就能写成这些积木的<b style="color:var(--teal)">加权叠加</b></p>
<p class="lead" style="font-size:30px;margin-top:24px;">就像把一个向量沿正交坐标轴分解——每个轴上投影多少,系数 $c_d$ 就有多大。</p>
</div>
</div>
</section>
<!-- 7 OU 衰减 -->
<section class="slide posCR">
<div class="glow amber"></div>
<div class="kicker"><span class="ln"></span>06 · 关键转折</div>
<h2>OU 过程让相关性<em>按阶数指数衰减</em></h2>
<div class="content" style="gap:60px;">
<div class="fbox" style="flex:.95;font-size:34px;">
$\mathbb{E}[He_n(z')He_n(z)]=\rho^{\,n}\cdot n!$
<div class="small">$z'=\rho z+\sqrt{1-\rho^2}\,\eta,\quad 0<\rho<1$</div>
</div>
<div style="flex:1.05;">
<div class="barrow"><span class="chip">1 阶</span><div class="track"><i style="width:90%"></i></div><span class="val">ρ¹</span></div>
<div class="barrow"><span class="chip">2 阶</span><div class="track"><i style="width:50%"></i></div><span class="val">ρ²</span></div>
<div class="barrow"><span class="chip">3 阶</span><div class="track"><i style="width:26%"></i></div><span class="val">ρ³</span></div>
<p class="lead" style="font-size:26px;margin-top:18px;">阶数越高 → 相关性掉得越快 → 高阶非线性几乎被冲淡。</p>
</div>
</div>
</section>
<!-- 8 线性可识别性 -->
<section class="slide">
<div class="glow"></div>
<div class="kicker"><span class="ln"></span>07 · 结论</div>
<h2>最优解:<em>只保留线性成分</em></h2>
<div class="content">
<ul class="pts">
<li>对齐损失要<b>最大化</b>正样本对的相关性。</li>
<li>线性成分贡献 $\rho$;非线性成分贡献 $\rho^d<\rho\ (d\ge 2)$,被打了折扣。</li>
<li>于是最优策略就是:<b>留下线性,丢掉所有非线性</b></li>
<li>模型被这个机制温柔地逼成一个本质线性的表示 —— 这就是<b>线性可识别性</b>,整套定理的直觉来源。</li>
</ul>
</div>
</section>
<!-- 9 谱权重 -->
<section class="slide posBL">
<div class="glow amber"></div>
<div class="kicker"><span class="ln"></span>08 · 度量工具</div>
<h2>谱权重:一张<em>能量饼图</em></h2>
<div class="content">
<div class="pie" style="background:conic-gradient(var(--teal) 0 62%, var(--amber) 62% 84%, #4a6b74 84% 100%);"></div>
<div class="legend">
<div class="li"><span class="dot" style="background:var(--teal)"></span>线性 $w_1$ —— 我们想要的成分</div>
<div class="li"><span class="dot" style="background:var(--amber)"></span>二阶 $w_2$ —— 被 OU 衰减更多</div>
<div class="li"><span class="dot" style="background:#4a6b74"></span>更高阶 —— 衰减最狠</div>
<div class="li" style="font-size:24px;color:var(--ink2);margin-top:14px;font-family:'JetBrains Mono',monospace;">
$w_d\ge 0,\quad w_0=0,\quad \textstyle\sum w_d=1$</div>
<div class="li" style="font-size:25px;color:var(--ink2);">理想状态:整张饼都给线性那一块。</div>
</div>
</div>
</section>
<!-- 10 小结 -->
<section class="slide posCR">
<div class="glow"></div>
<div class="kicker"><span class="ln"></span>09 · 小结</div>
<h2>四句话<em>带走全场</em></h2>
<div class="content">
<div class="grid4">
<div class="g"><div class="n">01</div><div class="t">Hermite 是高斯世界的<b>频率分解工具</b>,类比傅里叶。</div></div>
<div class="g"><div class="n">02</div><div class="t"><b>正交性</b>让任意合理函数都能干净地拆成这些积木叠加。</div></div>
<div class="g"><div class="n">03</div><div class="t">OU 过程使相关性按 <b>ρᵈ</b> 指数衰减,高阶削减更狠。</div></div>
<div class="g"><div class="n">04</div><div class="t">最大化相关性 → 只留线性 → <b>线性可识别性</b></div></div>
</div>
</div>
</section>
<!-- 11 尾页 -->
<section class="slide cover posBL">
<div class="glow amber"></div>
<div class="kicker"><span class="ln"></span>下一站</div>
<h1 style="font-size:92px;margin-top:30px;">Mehler 公式<br><em>把直觉坐实</em></h1>
<p class="lead" style="margin-top:34px;font-size:30px;">下一讲深入 $\rho^d$ 衰减的来源 —— 它来自 OU 过程的转移核在 Hermite 基下的展开。</p>
<div class="meta">谢谢收听 · 配套音频 hermite_polynomials-podcast.mp3 · 我们下次见</div>
</section>
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{left:'$', right:'$', display:false}
],
throwOnError:false
});
} else { setTimeout(renderMath, 120); }
}
// URL 参数:?page=N1-based 定位单页,用于截图/导出)、?clean=1(隐藏 UI
const params = new URLSearchParams(location.search);
const pageParam = params.get('page');
if (pageParam !== null) {
const p = parseInt(pageParam, 10);
if (!isNaN(p) && p >= 1 && p <= total) cur = p - 1;
}
if (params.get('clean') === '1') {
document.body.classList.add('clean');
const navEl = document.querySelector('.nav'); if (navEl) navEl.style.display = 'none';
const hk = document.querySelector('.hintkey'); if (hk) hk.style.display = 'none';
}
window.addEventListener('DOMContentLoaded', () => { renderMath(); show(cur); });
// 兜底:若 DOMContentLoaded 已过
if (document.readyState !== 'loading') { renderMath(); show(cur); }
</script>
</body>
</html>