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+\documentclass{article}
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+\usepackage[pdftex,active,tightpage]{preview}
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+\setlength\PreviewBorder{2mm}
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+
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+\usepackage[utf8]{inputenc} % this is needed for umlauts
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+\usepackage[ngerman]{babel} % this is needed for umlauts
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+\usepackage[T1]{fontenc} % this is needed for correct output of umlauts in pdf
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+\usepackage{amssymb,amsmath,amsfonts} % nice math rendering
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+\usepackage{braket} % needed for \Set
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+\usepackage{caption}
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+\usepackage{algorithm}
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+\usepackage{xcolor}
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+\usepackage[noend]{algpseudocode}
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+\usepackage{mathtools,bm}
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+\DeclareMathOperator*{\argmax}{arg\,max}
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+
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+\DeclareCaptionFormat{myformat}{#3}
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+\captionsetup[algorithm]{format=myformat}
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+
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+\begin{document}
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+\begin{preview}
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+ \begin{algorithm}[H]
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+ \begin{algorithmic}
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+ \Require
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+ \Statex Sates $\mathcal{X} = \{1, \dots, n_x\}$
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+ \Statex Actions $\mathcal{A} = \{1, \dots, n_a\},\qquad A: \mathcal{X} \Rightarrow \mathcal{A}$
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+ \Statex Reward function $R: \mathcal{X} \times \mathcal{A} \rightarrow \mathbb{R}$
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+ \Statex Black-box (probabilistic) transition function $T: \mathcal{X} \times \mathcal{A} \rightarrow \mathcal{X}$
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+ \Statex Learning rate $\alpha \in [0, 1]$, typically $\alpha = 0.1$
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+ \Statex Discounting factor $\gamma \in [0, 1]$
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+ \Statex $\lambda \in [0, 1]$: Trade-off between TD and MC
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+ \Procedure{QLearning}{$\mathcal{X}$, $A$, $R$, $T$, $\alpha$, $\gamma$, $\lambda$}
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+ \State Initialize $Q: \mathcal{X} \times \mathcal{A} \rightarrow \mathbb{R}$ arbitrarily
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+ \State Initialize $e: \mathcal{X} \times \mathcal{A} \rightarrow \mathbb{R}$ with 0. \Comment{eligibility trace}
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+ % \State Start in state $s \in \mathcal{X}$
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+ \While{$Q$ is not converged}
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+ \State Select $(s, a) \in \mathcal{X} \times \mathcal{A}$ arbitrarily
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+ \While{$s$ is not terminal}
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+ \State $r \gets R(s, a)$
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+ \State $s' \gets T(s, a)$ \Comment{Receive the new state}
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+ \State Calculate $\pi$ based on $Q$ (e.g. epsilon-greedy)
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+ \State {$\color{red} a^* \gets \argmax_{\tilde{a}} Q(s', \tilde{a})$}
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+ \State $a' \gets \pi(s')$
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+ \State $e(s, a) \gets e(s, a) + 1$
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+ \State $\delta \gets r + \gamma \cdot Q(s', {\color{red} a^*}) - Q(s, a)$
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+ \For{$(\tilde{s}, \tilde{a}) \in \mathcal{X} \times \mathcal{A}$}
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+ \State $Q(\tilde{s}, \tilde{a}) \gets Q(\tilde{s}, \tilde{a}) + \alpha \cdot \delta \cdot e(\tilde{s}, \tilde{a})$
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+ \State ${\color{red} e(\tilde{s}, \tilde{a}) \gets \begin{cases}\gamma \cdot \lambda \cdot e(\tilde{s}, \tilde{a})&\text{if } a' = a^*\\
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+ 0 &\text{otherwise}\end{cases}}$
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+ \EndFor
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+ \State $s \gets s'$
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+ \State $a \gets a'$
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+ \EndWhile
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+ \EndWhile
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+ \Return $Q$
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+ \EndProcedure
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+ \end{algorithmic}
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+ \caption{SARSA($\lambda$): Learn function $Q: \mathcal{X} \times \mathcal{A} \rightarrow \mathbb{R}$}
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+ \label{alg:sarsa-lambda}
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+ \end{algorithm}
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+\end{preview}
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+\end{document}
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