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author | Franciszek Malinka <franciszek.malinka@gmail.com> | 2022-02-16 14:06:29 +0100 |
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committer | Franciszek Malinka <franciszek.malinka@gmail.com> | 2022-02-16 14:06:29 +0100 |
commit | e48745a4ecae399b000828b02ff69ec3ea4febef (patch) | |
tree | 91afd7626654fe82b1156777e7f3386196ded835 /lic_malinka.tex | |
parent | 87b6137f59c74e6e52fa4bf761b5ec1ad8fcab7a (diff) |
Corollary 2.15
Diffstat (limited to 'lic_malinka.tex')
-rw-r--r-- | lic_malinka.tex | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/lic_malinka.tex b/lic_malinka.tex index 0b03eb7..62d1f7b 100644 --- a/lic_malinka.tex +++ b/lic_malinka.tex @@ -255,15 +255,25 @@ % \item rozwinąć \ref{lemma:comprehensive_lemma} (ii), poza tym $W_{n+1}$ jest dokładnie równy, a nie tylko superset, dodać kwantyfikator na n, a może wplecić jeszcze to że te rodziny $W_n$ też są rozłączne?
% \end{itemize}
+ \begin{corollary}
+ \label{corollary:banach-mazur-basis}
+ If we add a constraint to the Banach-Mazur game such that players can only choose basic open sets, then the theorem \ref{theorem:banach_mazur_thm} still suffices.
+ \end{corollary}
+
+ \begin{proof}
+ If one adds the word \textit{basic} before each occurance of word \textit{open} in previous proofs and theorems then they all will still be valid (except for $\Rightarrow$, but its an easy fix -- take $V_n$ a basic open subset of $U_n\cap A_n$).
+ \end{proof}
+
+ This corollary will be important in using the theorem in practice -- it's much easier to work with basic open sets rather than any open sets.
+
\subsection{Fraïssé classes}
\begin{fact}[Fraïssé theorem]
\label{fact:fraisse_thm}
% Suppose $\cC$ is a class of finitely generated $L$-structures such that...
- Then there exists a unique up to isomorphism counable $L$-structure $M$ such that...
+ Then there exists a unique up to isomorphism countable $L$-structure $M$ such that...
\end{fact}
-
\begin{definition}
For $\cC$, $M$ as in Fact~\ref{fact:fraisse_thm}, we write $\Flim(\cC)\coloneqq M$.
\end{definition}
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