mjo-set: adopt basic set operations from mjo-common.

[mjotex.git] / examples.tex

diff --git a/examples.tex b/examples.tex
index e11815ef7856b47f0dd5cb0e775c3272caeec427..f922d655715645da0e00309d1fb7973f7f4b3c51 100644 (file)
--- a/examples.tex
+++ b/examples.tex
@@ -100,39 +100,21 @@
     %
     The factorial of the number $10$ is $\factorial{10}$.
 
-    The Cartesian product of two sets $A$ and $B$ is
-    $\cartprod{A}{B}$; if we take the product with $C$ as well, then
-    we obtain $\cartprodthree{A}{B}{C}$. The direct sum of $V$ and $W$
-    is $\directsum{V}{W}$. Or three things,
-    $\directsumthree{U}{V}{W}$. How about more things? Like
-    $\directsummany{k=1}{\infty}{V_{k}} \ne
-    \cartprodmany{k=1}{\infty}{V_{k}}$. Those direct sums and
-    cartesian products adapt nicely to display equations:
+    The direct sum of $V$ and $W$ is $\directsum{V}{W}$. Or three
+    things, $\directsumthree{U}{V}{W}$. How about more things? Like
+    $\directsummany{k=1}{\infty}{V_{k}}$. Those direct sums
+    adapt nicely to display equations:
     %
     \begin{equation*}
-      \directsummany{k=1}{\infty}{V_{k}} \ne \cartprodmany{k=1}{\infty}{V_{k}}.
+      \directsummany{k=1}{\infty}{V_{k}} \ne \emptyset.
     \end{equation*}
     %
     Here are a few common tuple spaces that should not have a
     superscript when that superscript would be one: $\Nn[1]$,
     $\Zn[1]$, $\Qn[1]$, $\Rn[1]$, $\Cn[1]$. However, if the
     superscript is (say) two, then it appears: $\Nn[2]$, $\Zn[2]$,
-    $\Qn[2]$, $\Rn[2]$, $\Cn[2]$.
-
-    We also have a few basic set operations, for example the union of
-    two or three sets: $\union{A}{B}$, $\unionthree{A}{B}{C}$. And of
-    course with union comes intersection: $\intersect{A}{B}$,
-    $\intersectthree{A}{B}{C}$. We can also take an arbitrary
-    (indexed) union and intersections of things, like
-    $\unionmany{k=1}{\infty}{A_{k}}$ or
-    $\intersectmany{k=1}{\infty}{B_{k}}$. The best part about those
-    is that they do the right thing in a display equation:
-    %
-    \begin{equation*}
-      \unionmany{k=1}{\infty}{A_{k}} = \intersectmany{k=1}{\infty}{B_{k}}
-    \end{equation*}
-    %
-    Finally, we have the four standard types of intervals in $\Rn[1]$,
+    $\Qn[2]$, $\Rn[2]$, $\Cn[2]$. Finally, we have the four standard
+    types of intervals in $\Rn[1]$,
     %
     \begin{align*}
       \intervaloo{a}{b} &= \setc{ x \in \Rn[1]}{ a < x < b },\\
@@ -310,6 +292,29 @@
   \begin{section}{Set theory}
     The cardinality of the set $X \coloneqq \set{1,2,3}$ is $\card{X}
     = 3$, and its powerset is $\powerset{X}$.
+
+    We also have a few basic set operations, for example the union of
+    two or three sets: $\union{A}{B}$, $\unionthree{A}{B}{C}$. And of
+    course with union comes intersection: $\intersect{A}{B}$,
+    $\intersectthree{A}{B}{C}$. The Cartesian product of two sets $A$
+    and $B$ is there too: $\cartprod{A}{B}$. If we take the product
+    with $C$ as well, then we obtain $\cartprodthree{A}{B}{C}$.
+
+    We can also take an arbitrary (indexed) union, intersection, or
+    Cartesian product of things, like
+    $\unionmany{k=1}{\infty}{A_{k}}$,
+    $\intersectmany{k=1}{\infty}{B_{k}}$, or
+    $\cartprodmany{k=1}{\infty}{C_{k}}$. The best part about those is
+    that they do the right thing in a display equation:
+    %
+    \begin{equation*}
+      \unionmany{k=1}{\infty}{A_{k}}
+      \ne
+      \intersectmany{k=1}{\infty}{B_{k}}
+      \ne
+      \cartprodmany{k=1}{\infty}{C_{k}}.
+    \end{equation*}
+    %
   \end{section}
 
   \begin{section}{Theorems}