\begin{frame}{Reflexivity of Equality} We can derive \begin{talign} \vdash\; \myall{x}{x = x} \end{talign} as follows: \medskip \begin{exampleblock}{} \begin{tikzpicture} \naturaldeduction{ \namedproofbox{y}{ \proofstep{$y=y$}{$=_i$}; } \proofstep{$\myall{x}{x=x}$}{$\forall_i\;$ 1--1}; } \end{tikzpicture} \end{exampleblock} \end{frame}