\begin{frame}[t]{At Most One} \examplemodel \pause\bigskip \sentence{At most one $R$-loop:} \pause \begin{talign} \model{\amodel} \satisfies \formula{\forallst{x}{\forall{y}{(\binpred{{\black{R}}}{x}{x} \logandinf \binpred{{\black{R}}}{y}{y} \logimpinf \equalto{x}{y})}}} \end{talign} \pause \sentence{Not at least two $R$-loops:} \pause \begin{talign} \model{\amodel} \satisfies \formula{\lognot{\existsst{x}{\existsst{y}{(\binpred{{\black{R}}}{x}{x} \logandinf \binpred{{\black{R}}}{y}{y} \logandinf \notequalto{x}{y})}}}} \end{talign} \pause Both sentences are equivalent because: \begin{scenter} \sentence{at most one} ($\le 1$) $\iff$ \sentence{not at least two} (not $\ge 2$) \end{scenter} \end{frame}