diff options
Diffstat (limited to 'library/topology')
| -rw-r--r-- | library/topology/separation.tex | 10 | ||||
| -rw-r--r-- | library/topology/topological-space.tex | 136 |
2 files changed, 135 insertions, 11 deletions
diff --git a/library/topology/separation.tex b/library/topology/separation.tex index 530a51f..535a51f 100644 --- a/library/topology/separation.tex +++ b/library/topology/separation.tex @@ -75,11 +75,8 @@ Let $X$ be a \teeone-space. Assume $x \in \carrier[X]$. Then $\{x\}$ is closed in $X$. - %Then for all $x\in\carrier[X]$ we have $\{x\}$ is closed in $X$. Ambigus Phrase. if Omitted is ereased. \end{proposition} \begin{proof} - %Omitted. - %Fix $x \in X$. Let $V = \{ U \in \opens[X] \mid x \notin U\}$. For all $y \in \carrier[X]$ such that $x \neq y$ there exist $U \in \opens[X]$ such that $x \notin U \ni y$. For all $y \in \carrier[X]$ such that $y \neq x$ there exists $U \in V$ such that $y \in U$. @@ -99,13 +96,6 @@ For all $y \in \unions{V}$ we have $y \in \carrier[X] \setminus \{x\}$. Follows by set extensionality. \end{subproof} - % Let $U_{y} \in \opens[X]$ such that $x \neq y \in X$. Error: unexpected '{' expecting digit - %For all $y$ there exists $U$ such that $x \neq y$ and $y \in U$ and $U \in \opens[X]$. - - % TODO - % Choose for every y distinct from x and open subset U_y containing y but not x. - % The union U of all the U_y is open. - % {x} is the complement of U in \carrier[X]. \end{proof} % % Conversely, if \{x\} is open, then for any y distinct from x we can use diff --git a/library/topology/topological-space.tex b/library/topology/topological-space.tex index 2bbdf09..2590287 100644 --- a/library/topology/topological-space.tex +++ b/library/topology/topological-space.tex @@ -217,12 +217,146 @@ \end{proof} +%Def: $\inters{A} = \{ x\in\unions{A}\mid \text{for all $a\in A$ we have $x\in a$} \}$. + +\begin{proposition}\label{subseteq_inters_iff_to_right} + Let $A,F$ be sets. + Suppose $A \subseteq \inters{F}$. + Then for all $X \in F$ we have $A \subseteq X$. +\end{proposition} + + +\begin{proposition}\label{subseteq_of_all_then_subset_of_union} + Let $A,F$ be sets. + Suppose for all $X \in F$ we have $A \subseteq X$. + Then $A \subseteq \unions{F}$. +\end{proposition} +\begin{proof} + \begin{byCase} + \caseOf{$F$ is empty.} Trivial. + \caseOf{$F$ is inhabited.} + There exist $X \in F$ such that $X \subseteq \unions{F}$. + $A \subseteq X \subseteq \unions{F}$. + \end{byCase} +\end{proof} + +\begin{proposition}\label{subseteq_inters_iff_to_left} + Let $A,F$ be sets. + Suppose for all $X \in F$ we have $A \subseteq X$. + Then $A \subseteq \inters{F}$. +\end{proposition} +\begin{proof} + \begin{byCase} + \caseOf{$A = \emptyset$.}Trivial. + \caseOf{$A \neq \emptyset$.} + It suffices to show that for all $a \in A$ we have $a \in \inters{F}$. + Fix $a \in A$. + For all $X \in F$ we have $a \in X$. + $A \subseteq \unions{F}$. + $a \in \unions{F}$. + \end{byCase} + + %It suffices to show that for all $a \in A$ we have $x \in \inters{F}$. % This have been proven!!! But it shouldn't. + +% we show that there exist $Y \in F$ such that $a \in Y$. +% \begin{subproof} + +% \begin{byCase} +% \caseOf{$a = \emptyset$.} +% $\emptyset \subseteq \inters{F}$. +% $\emptyset \in \emptyset$. +% \caseOf{$a \neq \emptyset$.} Omitted. +% \end{byCase} + + %cases by a = \emptyset + %case a \neq \emptyset +% \end{subproof} +\end{proof} + +%------------------------ Only example ------------------------------------- +\begin{proposition}\label{subseteq_inters_iff_new} + $A \subseteq \inters{F}$ iff for all $X \in F$ we have $A \subseteq X$. +\end{proposition} +%\begin{proof} +% We show that if $A \subseteq \inters{F}$ then for all $X \in F$ we have $A \subseteq X$. +% \begin{subproof} + %It suffices to show that for all $a,X$ such that $a \in A$ and $X \in F$ we have $a \in X$. + %Fix $a \in A$. + %Fix $X \in F$. %TODO: Missmatched Assume! + +% It suffices to show that for all $a,X$ such that $a \in A$ and $X \in F$ we have $a \in X$. +% Follows by \cref{inters}. +% \end{subproof} +% We show that for all $X \in F$ such that $A \subseteq X$ we have $A \subseteq \inters{F}$. +% \begin{subproof} +% Omitted. +% \end{subproof} +%\end{proof} + +\begin{proposition}\label{set_is_subseteq_to_closure_of_the_set} + $A \subseteq \closure{A}{X}$. +\end{proposition} +\begin{proof} + %$\closures{A}{X}$ is inhabited. %TODO: Inhabited why does "subseteq_inters_iff" has inhabited as assumtion?? + For all $A' \in \closures{A}{X}$ we have $A \subseteq A'$. + Therefore $A \subseteq \inters{\closures{A}{X}}$. +\end{proof} + +\begin{proposition}\label{complement_of_closure_of_complement_of_x_subseteq_x} + $(\carrier[X] \setminus \closure{(\carrier[X]\setminus A)}{X}) \subseteq A$. +\end{proposition} +\begin{proof} + It suffices to show that for all $x \in (\carrier[X] \setminus \closure{(\carrier[X]\setminus A)}{X})$ we have $x \in A$. + If $x \in \carrier[X]\setminus A$ then $x \in \closure{(\carrier[X]\setminus A)}{X}$. + +\end{proof} + \begin{proposition}%[Complement of interior equals closure of complement] \label{complement_interior_eq_closure_complement} + Let $X$ be a topological space. $\carrier[X]\setminus\interior{A}{X} = \closure{(\carrier[X]\setminus A)}{X}$. \end{proposition} \begin{proof} - Omitted. % Use general De Morgan's Law in Pow|X| + We show that for all $x \in \carrier[X]\setminus\interior{A}{X}$ we have $x \in \closure{(\carrier[X]\setminus A)}{X}$. + \begin{subproof} + Fix $x \in \carrier[X]\setminus\interior{A}{X}$. + Suppose not. + $x \notin \closure{(\carrier[X]\setminus A)}{X}$. + $x \in \carrier[X]$. + For all $x \in X$ such that $A \union B = X$ and $A \inter B = \emptyset$ we have $x \in A \implies x \notin B$. + For all $x \in X$ such that $A \union B = X$ and $A \inter B = \emptyset$ we have $x \notin A \implies x \in B$. + $(\carrier[X] \setminus \closure{(\carrier[X]\setminus A)}{X}) \inter \closure{(\carrier[X]\setminus A)}{X} = \emptyset$. + %$(\carrier[X] \setminus \closure{(\carrier[X]\setminus A)}{X}) \subseteq A$. %TODO: + $x \in A$. + $x \in A \inter (\carrier[X] \setminus \closure{(\carrier[X]\setminus A)}{X})$. + $\carrier[X] \setminus \closure{(\carrier[X]\setminus A)}{X} \in \opens[X]$. %TODO: + Contradiction. + \end{subproof} + + $\carrier[X]\setminus\interior{A}{X} \subseteq \closure{(\carrier[X]\setminus A)}{X}$. + + $\closure{(\carrier[X]\setminus A)}{X} \subseteq \carrier[X]\setminus\interior{A}{X}$. %TODO: + + %We show that for all $x \in \carrier[X]\setminus\interior{A}{X}$ we have $x \in \closure{(\carrier[X]\setminus A)}{X}$. + %\begin{subproof} + % Fix $x \in \carrier[X]\setminus\interior{A}{X}$. + % \begin{byCase} + % \caseOf{$x \in \carrier[X] \setminus A$.} + % Trivial. + % \caseOf{$x \in \carrier[X] \setminus A \inter \interior{A}{X}$.} + % $\carrier[X] \setminus \closure{A}{X} \in \opens[X]$. + % $\interior{A}{X} \in \opens[X]$. + % Therefore $\carrier[X] \setminus \closure{A}{X} \inter \interior{A}{X} \in \opens[X]$. + % %$\carrier[X] \setminus \closure{A}{X}$ is open. TODO: is open throws an error! + % %$\interior{A}{X}$ is open. + % %Therefore $\carrier[X] \setminus \closure{A}{X} \inter \interior{A}{X}$ is open. + % + % \end{byCase} + %\end{subproof} + %Suffices reduction by \cref ::::: reduction => goal. + + + %Omitted. % Use general De Morgan's Law in Pow|X| \end{proof} \begin{definition}[Frontier]\label{frontier} |