答案1
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{positioning}
\begin{document}
\begin{tikzpicture}
\node(w){$w^{(\bot)}$};
\node[below=of w](z){$z^{(\bot)}$};
\node[right=of z](a){$a^{(2)}$};
\draw[->] (w) -- node[right]{$L^{(\bot)}$} (z);
\draw[->] (z) -- node[above]{$\alpha^{(\bot)}$} (a);
\draw (z) |- +(-0.6,0.8) node[left]{$x_i$};
\end{tikzpicture}
\end{document}