1 files changed, 14 insertions, 0 deletions
diff --git a/library/cardinal.tex b/library/cardinal.tex
new file mode 100644
index 0000000..d0dec59
--- /dev/null
+++ b/library/cardinal.tex
@@ -0,0 +1,14 @@
+\section{Cardinality}
+
+\import{set.tex}
+\import{ordinal.tex}
+\import{function.tex}
+
+\begin{definition}\label{finite}
+    $X$ is finite iff there exists a natural number $k$ such that
+        there exists a bijection from $k$ to $X$.
+\end{definition}
+
+\begin{abbreviation}\label{infinite}
+    $X$ is infinite iff $X$ is not finite.
+\end{abbreviation}