diff options
Diffstat (limited to 'library/set.tex')
| -rw-r--r-- | library/set.tex | 19 |
1 files changed, 8 insertions, 11 deletions
diff --git a/library/set.tex b/library/set.tex index 33e5af4..2fd18ea 100644 --- a/library/set.tex +++ b/library/set.tex @@ -131,8 +131,7 @@ which applies it to goals of the form “$A = B$” and “$A \neq B$”. If $x$ and $y$ are empty, then $x = y$. \end{proposition} -\begin{proposition}% -\label{emptyset_subseteq} +\begin{proposition}\label{emptyset_subseteq} For all $a$ we have $\emptyset \subseteq a$. % LATER $\emptyset$ is a subset of every set. \end{proposition} @@ -266,8 +265,7 @@ The $\operatorname{\textsf{cons}}$ operation is determined by the following axio There exists $B\in C$ such that $A\in B$. \end{proof} -\begin{proposition}% -\label{unions_emptyset} +\begin{proposition}\label{unions_emptyset} $\unions{\emptyset} = \emptyset$. \end{proposition} @@ -553,13 +551,7 @@ The $\operatorname{\textsf{cons}}$ operation is determined by the following axio Follows by set extensionality. \end{proof} -\begin{proposition}% -\label{inter_subseteq} - $A\inter B\subseteq A$. -\end{proposition} - -\begin{proposition}% -\label{inter_emptyset} +\begin{proposition}\label{inter_emptyset} $A\inter\emptyset = \emptyset$. \end{proposition} \begin{proof} @@ -620,6 +612,11 @@ The $\operatorname{\textsf{cons}}$ operation is determined by the following axio Follows by set extensionality. \end{proof} +\begin{proposition}\label{inter_subseteq} + Suppose $A,B\subseteq C$. + Then $A\inter B\subseteq C$. +\end{proposition} + \begin{abbreviation}\label{closedunderinter} $T$ is closed under binary intersections iff for every $U,V\in T$ we have $U\inter V\in T$. |
