diff options
author | Franciszek Malinka <franciszek.malinka@gmail.com> | 2022-05-03 13:12:54 +0200 |
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committer | Franciszek Malinka <franciszek.malinka@gmail.com> | 2022-05-03 13:12:54 +0200 |
commit | 29fb1dc0cb80c83f071079009ba487720685f05a (patch) | |
tree | f9a1fc16816ee8b77bc541bed7aea77c52bf9536 /lic_malinka.tex | |
parent | 80d1346f17a3ae138cf84cb25f27a6ff6ccf4696 (diff) |
poprawki do kluczowego dowodu
Diffstat (limited to 'lic_malinka.tex')
-rw-r--r-- | lic_malinka.tex | 81 |
1 files changed, 47 insertions, 34 deletions
diff --git a/lic_malinka.tex b/lic_malinka.tex index fe992a1..5e52034 100644 --- a/lic_malinka.tex +++ b/lic_malinka.tex @@ -663,6 +663,7 @@ beyond equality).
\begin{proposition}
+ \label{proposition:cojugate-classes}
If $f_1,f_2\in \Aut(M)$, then $f_1$ and $f_2$ are conjugate if and only
if for each $n\in \bN\cup \{\aleph_0\}$, $f_1$ and $f_2$ have the same
number of orbits of size $n$.
@@ -703,20 +704,11 @@ is an open dense set. It is a sum over basic open sets generated by finite
permutations with $m$ in their domain. Denseness is also easy to see.
- Finally, we can say that
+ Finally, by the proposition \ref{proposition:cojugate-classes}, we can say that
$$\sigma^{\Aut(M)}=\bigcap_{n=1}^\infty A_n \cap \bigcap_{m\in M} B_m,$$
which concludes the proof.
-
\end{proof}
- % \begin{proposition}
- % An automorphism $f$ of $M$ is generic if and only if...
- % \end{proposition}
-
- % \begin{proof}
-
- % \end{proof}
-
\subsection{More general structures}
\begin{fact}
@@ -821,10 +813,18 @@ \begin{center}
\begin{tikzcd}
- (A_{i,j}, \alpha_{i,j}) \arrow[d, "\subseteq"'] \arrow[r, "f_{i,j}"] & (\FrGr_{n-1}, g_{n-1}) \arrow[d, "\subseteq"] \\
- (B_{i,j}, \beta_{i,j}) \arrow[r, dashed, "\hat{f}_{i,j}"'] & (\FrGr_n, g_n)
+ & (\FrGr_n, g_n) & \\
+ (B_{i,j}, \beta_{i,j}) \arrow[ur, dashed, "\hat{f}_{i,j}"] & & (\FrGr_{n-1}, g_{n-1}) \arrow[ul, dashed, "\subseteq"'] \\
+ & (A_{i,j}, \alpha_{i,j}) \arrow[ur, "f_{i,j}"'] \arrow[ul, "\subseteq"]
\end{tikzcd}
\end{center}
+
+ % \begin{center}
+ % \begin{tikzcd}
+ % (A_{i,j}, \alpha_{i,j}) \arrow[d, "\subseteq"'] \arrow[r, "f_{i,j}"] & (\FrGr_{n-1}, g_{n-1}) \arrow[d, "\subseteq"] \\
+ % (B_{i,j}, \beta_{i,j}) \arrow[r, dashed, "\hat{f}_{i,j}"'] & (\FrGr_n, g_n)
+ % \end{tikzcd}
+ % \end{center}
\end{enumerate}
First item makes sure that no infinite orbit will not be present in $g$. The
@@ -832,23 +832,35 @@ automorphism of $\FrGr$. The third item is the one that gives weak
ultrahomogeneity. Now we will show that indeed such $g_n$ may be constructed.
- First, we will suffice the (iii) item. Namely, we will construct $\FrGr'_n, g'_n$
+ First, we will suffice the item (iii). Namely, we will construct $\FrGr'_n, g'_n$
such that $g_{n-1}\subseteq g'_n$ and $f_{i,j}$ extends to an embedding of
- $(B_{i,j}, \beta_{i,j})$ to $(\FrGr'_n, g'_n)$. Without the loss of generality
- we may assume that $f_{i,j}$ is an inclusion and that $A_{i,j} = B_{i,j}\cap\FrGr_{n-1}$.
- Then let $\FrGr'_n = B_{i,j}\cup\FrGr_{n-1}$ and $g'_n = g_{n-1}\cup \beta_{i,j}$.
- Then $(B_{i,j}, \beta_{i,j})$ simply embeds by inclusion in $(\FrGr'_n, g'_n)$,
- i.e. this diagram commutes:
-
- \begin{center}
- \begin{tikzcd}
- (A_{i,j}, \alpha_{i,j}) \arrow[d, "\subseteq"'] \arrow[r, "\subseteq"] & (\FrGr_{n-1}, g_{n-1}) \arrow[d, "\subseteq"] \\
- (B_{i,j}, \beta_{i,j}) \arrow[r, dashed, "\subseteq"'] & (\FrGr'_n, g'_n)
- \end{tikzcd}
- \end{center}
-
- The argument that those are actually embeddings is almost the same as in
- proof of the amalgamation property of $\cH$.
+ $(B_{i,j}, \beta_{i,j})$ to $(\FrGr'_n, g'_n)$. But this can be easily
+ done by the fact, that $\cH$ has the amalgamation property. Moreover, without
+ the loss of generality we can assume that all embeddings are inclusions.
+
+ \begin{center}
+ \begin{tikzcd}
+ & (\FrGr'_n, g'_n) & \\
+ (B_{i,j}, \beta_{i,j}) \arrow[ur, dashed, "\subseteq"] & & (\FrGr_{n-1}, g_{n-1}) \arrow[ul, dashed, "\subseteq"'] \\
+ & (A_{i,j}, \alpha_{i,j}) \arrow[ur, "\subseteq"'] \arrow[ul, "\subseteq"]
+ \end{tikzcd}
+ \end{center}
+
+ % Without the loss of generality
+ % we may assume that $f_{i,j}$ is an inclusion and that $A_{i,j} = B_{i,j}\cap\FrGr_{n-1}$.
+ % Then let $\FrGr'_n = B_{i,j}\cup\FrGr_{n-1}$ and $g'_n = g_{n-1}\cup \beta_{i,j}$.
+ % Then $(B_{i,j}, \beta_{i,j})$ simply embeds by inclusion in $(\FrGr'_n, g'_n)$,
+ % i.e. this diagram commutes:
+
+ % \begin{center}
+ % \begin{tikzcd}
+ % (A_{i,j}, \alpha_{i,j}) \arrow[d, "\subseteq"'] \arrow[r, "\subseteq"] & (\FrGr_{n-1}, g_{n-1}) \arrow[d, "\subseteq"] \\
+ % (B_{i,j}, \beta_{i,j}) \arrow[r, dashed, "\subseteq"'] & (\FrGr'_n, g'_n)
+ % \end{tikzcd}
+ % \end{center}
+
+ % The argument that those are actually embeddings is almost the same as in
+ % proof of the amalgamation property of $\cH$.
It may be also assumed without the loss of generality that $\FrGr'_n\subseteq \FrGr$.
Of course by the recursive assumption $\FrGr_{n-1}\subseteq\FrGr$. The
@@ -858,12 +870,12 @@ Now, by the WHP of $\bK$ we can extend the graph $\FrGr'_n\cup\{v_n\}$ together
with its partial isomorphism $g'_n$ to a graph $\FrGr_n$ together with its
- automorphism $g_n\supseteq g'_n$, where without the loss of generality we
+ automorphism $g_n\supseteq g'_n$ and without the loss of generality we
may assume that $\FrGr_n\subseteq\FrGr$. This way we've constructed $g_n$
that has all desired properties.
Now we need to see that $g = \bigcap^{\infty}_{n=0}g_n$ is indeed an automorphism
- of $\FrGr$ such that $(\FrGr, g)$ has the age $\cH$ and has weak ultrahomogeneity.
+ of $\FrGr$ such that $(\FrGr, g)$ has the age $\cH$ and is weakly ultrahomogeneous.
It is of course an automorphism of $\FrGr$ as it is defined for every $v\in\FrGr$
and is a sum of increasing chain of finite automorphisms.
@@ -871,13 +883,14 @@ $i, j$ such that $(B, \beta) = (B_{i, j}, \beta_{i,j})$ and $A_{i,j}=\emptyset$.
By the bookkeeping there was $n$ such that $(i, j) = \min\{\{0,1,\ldots\}\times\bN\setminus X_{n-1}\}$.
This means that $(B, \beta)$ embeds into $(\FrGr_n, g_n)$, hence it embeds
- into $(\FrGr, g)$. With a similar argument we can see that $(\FrGr, g)$ is
- weakly ultrahomogeneous.
+ into $(\FrGr, g)$, thus it has age $\cH$.
+ With a similar argument we can see that $(\FrGr, g)$ is weakly ultrahomogeneous.
By this we know that $g$ and $\sigma$ conjugate in $G$. As we stated in the
- beginning of the proof, the set of possible outcomes of the game (i.e.
+ beginning of the proof, the set $A$ of possible outcomes of the game (i.e.
possible $g$'s we end up with) is comeagre in $G$, thus $\sigma^G$ is also
- comeagre and $\sigma$ is a generic automorphism.
+ comeagre and $\sigma$ is a generic automorphism, as it contains a comeagre
+ set $A$.
\end{proof}
\printbibliography
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