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tweaks to lecture 2
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sergeyplis committed Jan 16, 2025
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19 changes: 11 additions & 8 deletions cs8850_02_erm.html
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Expand Up @@ -108,7 +108,7 @@ <h3>setup</h3>
y_m))$. <br>Sequence of pairs in
$\cal{X}\times\cal{Y}$
</ul>
<li class="fragment" data-fragment-index="4">The learner's output
<li class="fragment" data-fragment-index="4">The learner's output (<span style="color: #DBD7D7;">ὑπόθεσις</span>)
<ul>
$h: \cal{X} \rightarrow \cal{Y}$
</ul>
Expand Down Expand Up @@ -303,7 +303,7 @@ <h3>Assumptions</h3>
<!-- $h_S \in \underset{h\in{\cal H}}{\argmin}L_S(h)$ -->
<!-- </dev><br> -->
<blockquote style="text-align: left;" style="background-color: #eee8d5;" class="fragment" data-fragment-index="0">
<b>The Realizability Assumption:</b> There exists $h^* \in {\cal H} s.t. L_{{\cal D}, f}(h^*)=0$. This implies: with probability 1 over random samples $S\sim {\cal D}$ labeled by $f$, we have $L_S(h^*)=0$
<b>The Realizability Assumption:</b> There exists $h^* \in {\cal H}$ s.t. $L_{{\cal D}, f}(h^*)=0$. This implies: with probability 1 over random samples $S\sim {\cal D}$ labeled by $f$, we have $L_S(h^*)=0$
</blockquote>
<blockquote style="text-align: left;" style="background-color: #eee8d5;" class="fragment" data-fragment-index="1">
<b>The i.i.d. Assumption:</b> Samples in the training set are independent and identically distributed. Denoted as $S\sim {\cal D}^m$
Expand Down Expand Up @@ -357,14 +357,14 @@ <h3>But remember our assumption?</h3>
<blockquote style="text-align: left;">
<b>The Realizability Assumption:</b> There exists $h^* \in {\cal H} s.t. L_{{\cal D}, f}(h^*)=0$. This implies: with probability 1 over random samples $S\sim {\cal D}$ labeled by $f$, we have $L_S(h^*)=0$
</blockquote>
Means $L_S(h_S) = 0$, where $h_S \in \underset{h\in{\cal H}}{\argmin}L_S(h)$. Hence $L_{({\cal D}, f)}(h_S) > \epsilon$ can only happen if for some $h\in {\cal H}_B$, $L_S(h)=0$
<span class="fragment" data-fragment-index="0" >Means $L_S(h_S) = 0$, where $h_S \in \underset{h\in{\cal H}}{\argmin}L_S(h)$.</span> <div class="fragment" data-fragment-index="1" >Hence $L_{({\cal D}, f)}(h_S) > \epsilon$ can only happen if for some $h\in {\cal H}_B$, $L_S(h)=0$</span>
<br>
<div class="fragment" data-fragment-index="0" >
<div class="fragment" data-fragment-index="2" >
follows $\{S\mid_x : L_{({\cal D}, f)}(h_S) > \epsilon \} \subseteq M$
</div>
</section>
<section>
<div class="fragment" data-fragment-index="0" >
<div class="fragment" data-fragment-index="2" >
We want to upperbound ${\cal D}^m(\{S\mid_x : L_{({\cal D}, f)}(h_S) > \epsilon\})$
</div>
<div class="fragment" data-fragment-index="1" >
Expand Down Expand Up @@ -392,10 +392,13 @@ <h3>Confidence and accuracy</h3>
</blockquote>
<div class="fragment" data-fragment-index="0">
hence<br>
${\cal D}^m(\{S\mid_x : L_{({\cal D}, f)}(h_S) > \epsilon\}) \le {\cal D}^m(\underset{h\in {\cal H}_B}\bigcup \{S\mid_x : L_{S}(h) = 0 \})$
<br>$\le \sum_{h\in {\cal H}_B}{\cal D}^m(\{S\mid_x : L_{S}(h) = 0 \})$
\begin{align}
{\cal D}^m(\{S\mid_x : L_{({\cal D}, f)}(h_S) > \epsilon\}) & \le \\
{\cal D}^m(\underset{h\in {\cal H}_B}\bigcup \{S\mid_x : L_{S}(h) = 0 \}) & \le \\
\sum_{h\in {\cal H}_B}{\cal D}^m(\{S\mid_x : L_{S}(h) = 0 \})
\end{align}
</div>
<div class="fragment" data-fragment-index="1">
<div class="fragment" data-fragment-index="1" style="margin-top:-50px;">
let's put a bound on each summand separately
</div>
</section>
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