From e157fa83770cf671d8b1ce897964ee5297e0b1eb Mon Sep 17 00:00:00 2001
From: Michael Orlitzky <michael@orlitzky.com>
Date: Mon, 26 Aug 2019 20:00:25 -0400
Subject: [PATCH] Add mjo-algebra.tex with \polyring and \Frac commands.

---
 GNUmakefile     |  9 ++++++---
 examples.tex    |  7 +++++++
 mjo-algebra.tex | 13 +++++++++++++
 mjotex.sty      |  1 +
 4 files changed, 27 insertions(+), 3 deletions(-)
 create mode 100644 mjo-algebra.tex

diff --git a/GNUmakefile b/GNUmakefile
index 4474d2f..78800b0 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -17,9 +17,12 @@ PN = examples
 
 # A space-separated list of the mjotex files that you use. The path to
 # mjotex must be contain in your $TEXINPUTS environment variable.
-MJOTEX  = mjo-algorithm.tex mjo-arrow.tex mjo-calculus.tex mjo-common.tex
-MJOTEX += mjo-complex.tex mjo-cone.tex mjo-convex.tex mjo-font.tex
-MJOTEX += mjo-linear_algebra.tex mjo-listing.tex mjo-misc.tex
+#
+# MJOTEX  = mjotex.sty
+#
+MJOTEX  = mjo-algebra.tex mjo-algorithm.tex mjo-arrow.tex mjo-calculus.tex
+MJOTEX += mjo-common.tex mjo-complex.tex mjo-cone.tex mjo-convex.tex
+MJOTEX += mjo-font.tex mjo-linear_algebra.tex mjo-listing.tex mjo-misc.tex
 MJOTEX += mjo-proof_by_cases.tex mjo-theorem.tex mjo-theorem-star.tex
 MJOTEX += mjo-topology.tex mjo.bst
 
diff --git a/examples.tex b/examples.tex
index 6e1c500..a43b26e 100644
--- a/examples.tex
+++ b/examples.tex
@@ -5,6 +5,13 @@
 
 \begin{document}
 
+  \begin{section}{Algebra}
+    If $R$ is a commutative ring, then $\polyring{R}{X,Y,Z}$ is a
+    multivariate polynomial ring with indeterminates $X$, $Y$, and
+    $Z$, and coefficients in $R$. If $R$ is a moreover an integral
+    domain, then its fraction field is $\Frac{R}$.
+  \end{section}
+
   \begin{section}{Algorithm}
     An example of an algorithm (bogosort) environment.
 
diff --git a/mjo-algebra.tex b/mjo-algebra.tex
new file mode 100644
index 0000000..d70d9fd
--- /dev/null
+++ b/mjo-algebra.tex
@@ -0,0 +1,13 @@
+% Needed for \operatorname.
+\usepackage{amsopn}
+
+% The fraction field of its argument, an integral domain. The name
+% "Frac" was chosen here instead of "Quot" because the latter
+% corresponds to the term "quotient field," which can be mistaken in
+% some cases for... a quotient field (something mod something).
+\newcommand*{\Frac}[1]{\operatorname{Frac}\of{{#1}}}
+
+% The polynomial ring whose underlying commutative ring of
+% coefficients is the first argument and whose indeterminates (a
+% comma-separated list) are the second argumnt.
+\newcommand*{\polyring}[2]{{#1}\left[{#2}\right]}
diff --git a/mjotex.sty b/mjotex.sty
index e01ea7b..39792d5 100644
--- a/mjotex.sty
+++ b/mjotex.sty
@@ -1,3 +1,4 @@
+\input{mjo-algebra}
 \input{mjo-algorithm}
 \input{mjo-arrow}
 \input{mjo-calculus}
-- 
2.44.2