From 29027c9d2cdbdfe59e48b5aa28eb2d32d1a4c1f7 Mon Sep 17 00:00:00 2001 From: Simon-Kor <52245124+Simon-Kor@users.noreply.github.com> Date: Sat, 24 Aug 2024 11:43:29 +0200 Subject: naproch sty extension --- library/topology/urysohn2.tex | 56 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) create mode 100644 library/topology/urysohn2.tex (limited to 'library/topology/urysohn2.tex') diff --git a/library/topology/urysohn2.tex b/library/topology/urysohn2.tex new file mode 100644 index 0000000..8e5261e --- /dev/null +++ b/library/topology/urysohn2.tex @@ -0,0 +1,56 @@ +\import{topology/topological-space.tex} +\import{topology/separation.tex} +\import{topology/continuous.tex} +\import{topology/basis.tex} +\import{numbers.tex} +\import{function.tex} +\import{set.tex} +\import{cardinal.tex} +\import{relation.tex} +\import{relation/uniqueness.tex} +\import{set/cons.tex} +\import{set/powerset.tex} +\import{set/fixpoint.tex} +\import{set/product.tex} + +\section{Urysohns Lemma} + + + +\begin{abbreviation}\label{urysohnspace} + $X$ is a urysohn space iff + $X$ is a topological space and + for all $A,B \in \closeds{X}$ such that $A \inter B = \emptyset$ + we have there exist $A',B' \in \opens[X]$ + such that $A \subseteq A'$ and $B \subseteq B'$ and $A' \inter B' = \emptyset$. +\end{abbreviation} + + +\begin{definition}\label{intervalclosed} + $\intervalclosed{a}{b} = \{x \in \reals \mid a \leq x \leq b\}$. +\end{definition} + + + + +\begin{theorem}\label{urysohn} + Let $X$ be a urysohn space. + Suppose $A,B \in \closeds{X}$. + Suppose $A \inter B$ is empty. + Suppose $\carrier[X]$ is inhabited. + There exist $f$ such that $f \in \funs{\carrier[X]}{\intervalclosed{\zero}{1}}$ + and $f(A) = \zero$ and $f(B)= 1$ and $f$ is continuous. +\end{theorem} +\begin{proof} + + + + + + Contradiction. + +\end{proof} + +\begin{theorem}\label{safe} + Contradiction. +\end{theorem} -- cgit v1.2.3