fixpoint-theory-nov24/note.tex

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\documentclass{article}
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\input{notation.tex}
\input{glossary.tex}
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\newtheorem{theorem}{Theorem}
\begin{document}
% \maketitle
\definition{monotone}{define monotone}
\definition{image}{define set image}
\definition{completelattice}{define complete lattice}
Hello world\cite{tarskilatticetheoretical1955}
First, we generalize Knaster-Tarski Fixpoint Theorem.
$$\fixpointsOf(S)$$
\begin{theorem}[Tarski-Knaster Fixpoint Theorem~\cite{tarskilatticetheoretical1955}]
For a \Monotone function $o$ over a \CompleteLattice $\langle \L, \lte \rangle$, we have that $\langle \fixpointsOf(o), \lte \rangle$ is a \CompleteLattice.
\end{theorem}
\begin{theorem}
For a \Monotone function $o$ over a \CompleteLattice $\langle \L, \lte \rangle$, we have that $\langle o\imageNoLink{\L}, \lte \rangle$ is a \CompleteLattice.
\end{theorem}
\begin{proof}
Consider $\langle \L', \lte' \rangle$ where
\begin{align*}
\L' \define \{ x' ~|~ x \in \L \} \\
x' \lte' y' \iff x \lte y \textrm{ where } x, y \in \L
\end{align*}
Clearly, $\langle \L', \lte' \rangle$ is a \CompleteLattice.
Combining $\L$ and $\L'$
\begin{align*}
\L^* \define \{ \top^*, \bot^* \} \union \L \union \L' \\
\forall x^*, y^* \in \L^*, x^* \lte y^* \iff \begin{cases}
(x^* = \bot^*) \lor (y^* = \top^*) \\
two \\
three
\end{cases}
\end{align*}
\end{proof}
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