diff --git a/draft/draft.tex b/draft/draft.tex index 7c8f56c..4a726ba 100644 --- a/draft/draft.tex +++ b/draft/draft.tex @@ -82,6 +82,8 @@ \usetikzlibrary{arrows.meta} \usetikzlibrary{decorations} % Required for all decorations \usetikzlibrary{decorations.pathmorphing} % Specifically for 'zigzag' +\usetikzlibrary{matrix,positioning,arrows.meta,shapes.geometric} + \tikzset{ commutative diagrams/.cd, @@ -1403,6 +1405,44 @@ We have two more notions for coalgebraic bisimulation in $\Set$, that is to defi \end{proof} % \subsection{Simulations in Set} + +%\begin{figure}[ht] +% \centering +% \begin{tabular}{|c|c|c|c|c|} +% \hline +% & \textbf{Hughes-Jacobs} & \textbf{Hermida-Jacobs} & \textbf{Span-based} & \textbf{Aczel-Mendler} \\ +% \hline +% $\appr\cdot-$ & ? & ? & ? & ? \\ +% \hline +% $-\cdot\appr$ & ? & ? & ? & ? \\ +% \hline +% $\appr\cdot-\cdot\appr$ & ? & ? & ? & ? \\ +% \hline +% \end{tabular} +% \caption{Comparison of anonymous and onymous settings for relations and spans in $\Set$.} +% \label{fig:anonymous_onymous_transposed} +%\end{figure} + + +\begin{tikzpicture}[ + scale=0.5, every node/.style={transform shape} +] +\matrix (m) [matrix of nodes, + nodes={draw, ellipse, minimum width=2.6cm, minimum height=1cm, + align=center, font=\scriptsize, inner sep=2pt}, + row sep=6mm, column sep=6mm] +{ + $\appr\cdot-$-Hughes-Jacobs & $\appr\cdot-$-Hermida-Jacobs & $\appr\cdot-$-Span-based & $\appr\cdot-$-Aczel-Mendler \\ + $-\cdot\appr$-Hughes-Jacobs & $-\cdot\appr$-Hermida-Jacobs & $-\cdot\appr$-Span-based & $-\cdot\appr$-Aczel-Mendler \\ + $\appr\cdot-\cdot\appr$-Hughes-Jacobs & $\appr\cdot-\cdot\appr$-Hermida-Jacobs & $\appr\cdot-\cdot\appr$-Span-based & $\appr\cdot-\cdot\appr$-Aczel-Mendler \\ +}; + +% Example arrows (uncomment / edit as needed): +\draw[-{Latex[length=2mm]}] (m-3-1) to[bend right=30] node[midway, above] {AC} (m-3-2); +\draw[-{Latex[length=2mm]}] (m-3-2) to[bend right=30] (m-3-1); + +\end{tikzpicture} + Traditionally, simulations in $\Set$ are defined using relators. In this section we make a comparison on this concept with the other notions of simulation that we mentioned. %\begin{notation} % We show the category of sets and binary relations with $\rels$, and we show a morphism in this category as $R\c X\rto Y$ that is a relation $R$. @@ -1417,7 +1457,7 @@ Traditionally, simulations in $\Set$ are defined using relators. In this section %\end{proof} %The above translation seems to be true in a more general case, where $\spa$ and $\rel$ are defined on an arbitrary category (the latter is called an allegory then). \begin{definition}[Relator]\label{def:relator} - Assuming $F$ is a functor on $\Set$, a $F$-relator or simply a relator $\relar$ is a monotone map that sends an object $(X \stackrel{p_1}{\leftarrow} R \stackrel{p_2}{\to}Y)$ of $\Rel$ to $(FX \stackrel{q_1}{\leftarrow} \relar R \stackrel{q_2}{\to}FY)$. + Assuming $F$ is a functor on $\Set$, an $F$-relator or simply a relator $\relar$ is a monotone map that sends an object $(X \stackrel{p_1}{\leftarrow} R \stackrel{p_2}{\to}Y)$ of $\Rel$ to $(FX \stackrel{q_1}{\leftarrow} \relar R \stackrel{q_2}{\to}FY)$. \end{definition} % %\begin{definition}[Hermida-Jacobs Simulation]\label{def:hej-sim-rela} @@ -1458,10 +1498,10 @@ Traditionally, simulations in $\Set$ are defined using relators. In this section \end{example} % \begin{prop}\label{prop:HeJ-HuJ} - For a functor $F\c\Set\to\Set$, every object $(X \stackrel{p_1}{\leftarrow} R \stackrel{p_2}{\to}Y)$ in $\rel$ from a coalgebra $(X,\alpha)$ to a coalgebra $(Y,\beta)$: +Given $F\c\Set\to\Set$ and an object $(X \stackrel{p_1}{\leftarrow} R \stackrel{p_2}{\to}Y)$ in $\rel$, \begin{enumerate} - \item is a $\tilde{F}$-simulation if it is a Hermida-Jacobs simulation. - \item is a Hermida-Jacobs simulation if it is a $\tilde{F}$-simulation, assuming the axiom of choice. + \item $(X \stackrel{p_1}{\leftarrow} R \stackrel{p_2}{\to}Y)$ is a $\tilde{F}$-simulation from a coalgebra $(X,\alpha)$ to a coalgebra $(Y,\beta)$ if it is a Hermida-Jacobs simulation. + \item $(X \stackrel{p_1}{\leftarrow} R \stackrel{p_2}{\to}Y)$ is a Hermida-Jacobs simulation from a coalgebra $(X,\alpha)$ to a coalgebra $(Y,\beta)$ if it is a $\tilde{F}$-simulation, assuming the axiom of choice. \end{enumerate} \end{prop} \begin{proof}