\documentclass{tac}

% Prepared using tac.cls and diagxy (if you do not have diagxy, compiling this will require commenting lines 149-152)
% PLEASE READ comments in the text below
% PLEASE NOTE: source files for submission to TAC require a comment like the following
%              giving format, style, packages used, TeX implementation
% LaTeX 2e document, TAC style, 2 pp, Xy-pic ver 3.7, MikTeX version 3.1


% NOTE: packages used should be the first part of the preamble

\usepackage{xy}
% diagxy loads xy, so the line preceding is redundant

\input diagxy

\def\xypic{\hbox{\rm\Xy-pic}}

% NOTE: TAC preamble macros come next...

\author {Michael Barr and Robert Rosebrugh}

% NOTE: that \thanks is outside the \author macro, unlike article style...

\thanks{We would like to thank Donald Knuth, Leslie Lamport, Kris
Rose, and all the others who make high quality math typesetting
possible.}

\address{Department of Mathematics and Statistics, McGill University\\
 805 Sherbrooke St. W, Montreal, QC, Canada H3A 2K6\\[5pt]
 Department of Mathematics and Computer Science, Mt. Allison
University\\67 York St., Sackville, NB, Canada E4L 1E6\\
}


\title {A TAC sampler}

% NOTE: this is required...

\copyrightyear{2003}

% NOTE: the next three are optional in this style (but \amsclass and \eaddress are required for TAC publication)

\keywords{TAC, diagrams}
\amsclass{00A00}
% NOTE: that \CR here provides a vertical listing

\eaddress{barr@barrs.org\CR rrosebrugh@mta.ca}


% NOTE: thirdly, author macros  BEGIN here
%       (they are all actually used in the article!!)
% *PLEASE* note the begin and end of author macros in the source file

\def\xypic{\hbox{\rm\Xy-pic}}

\newtheorem{thm}{Theorem}
%\newtheorem{prop}{Proposition}
\newtheorem{lem}{Lemma}
%\newtheorem{cor}{Corollary}
\let\pf\proof
\let\epf\endproof
\mathrmdef{Hom}
\mathbfdef{Set}

% author macros END here

\begin{document}

\maketitle
\begin{abstract}
 This is distributed as a sampler to illustrate good {\sl TAC} style.
\end{abstract}

% NOTE: it is good practice to label all headings (and proclamations) immediately

\section{Introduction}\label{sec-Introduction}

This note includes samples of what we consider good {\sl TAC} style.  You will
note that there are no explicit skips nor any other explicit formatting
instructions; these are left to the journal style.  For the same
reason, there is no explicit numbering of headings or proclamations of
Theorems and so forth, but they are labelled to allow
logical references, such as to Theorem \ref{thm-easy-style}.

\emph{Please note that there are additional comments in the source file
for this sampler that
you are urged to consult. Please \textbf{also} consult the on-line author instructions
on the {\sl TAC} web site.}

\section{Main results}\label{sec-Main-results}

%NOTE: more verbosely, the next line could use \begin{lem} ... \end{lem}

\lem\label{lem-latex-2e} All papers should be in \LaTeX, version 2e.\endlem

\pf Otherwise the editors will have to do a lot of work to prepare the
paper for publication.
\epf


\thm\label{thm-easy-style} The {\sl TAC} style is easy to use.\endthm

\pf
Sectioning is the same as in \LaTeX\ article style;
proclamations such as definitions and theorems are easily specified
by macros such as \verb.\newtheorem{thm}{Theorem}.;
it is easy to define a macro \verb.\Hom. that produces
roman $\Hom$ when used in math mode.  Similarly \verb.\Set. gives $\Set$
in bold.
\epf

% NOTE: If you use \cite at the beginning of a theorem-like environment,
% it must come immediately after the theorem and before any label.

\thm[\cite{LUG}]\label{thm-Lamport-1986}  The following are equivalent
\begin{enumerate}
\item Lists are best done with listing macros such as enumerate;

\item you will never have to renumber anything if you use automatic
numbering of lists and other things.
\end{enumerate}

\epf\endthm

\section{Further comments}\label{sec-Further-comments}


\begin{list}{}{}
\item[$\bullet$] Source files should include \emph{all} and
\emph{only} author macros that are actually used. \item[$\bullet$]
Be sure to use macros for multicharacter identifiers, such as
\verb.\Hom. above. \item[$\bullet$] Be sure to distinguish between
$<$ and $\langle$ and similarly between $>$ and $\rangle$.  Not
only does the former character look wrong as a tuple delimiter,
but the spacing is completely wrong. \item[$\bullet$] For
diagrams, use \xypic or diagxy.% , or Paul Taylor's diagram package.
They can be used together since diagxy is built on top of
\xypic. A syntax example from the diagxy manual is
\begin{verbatim}
$$\bfig
  \square/>>`>`>` >->/[A`B`C`D;e`f`g`m]
  \morphism(500,500)|m|/.>/<-500,-500>[B`C;h]
\efig$$
\end{verbatim}
which makes a familiar diagram:
% NOTE: If you do not have XY-pic and diagxy installed you will have to comment out
%       the next four lines.

$$\bfig
 \square/>>`>`>` >->/[A`B`C`D;e`f`g`m]
 \morphism(500,500)|m|/.>/<-500,-500>[B`C;h]
\efig$$
\item[$\bullet$] Although we accept most reasonable bibliographical styles, the
 following is the one we most strongly recommend.  It results in the
 author, year entry in the paper, rather than uninformative numbers in
 brackets. It allows use of e.g. \verb.\cite{LUG}. and the code for this article is:
\begin{verbatim}
\refs

\bibitem [Lamport, 1986]{LUG} L. Lamport, Latex User's Guide \&
Reference Manual. Addison-Wesley (fifth edition), 1986.

\endrefs
\end{verbatim}
\end{list}

 % Note: Although we accept most reasonable bibliographical styles, the
 % following is the one we most strongly recommend.  It results in the
 % author, year entry in the paper, rather than uninformative numbers in
 % brackets.

\refs

\bibitem [Lamport, 1986]{LUG} L. Lamport, Latex User's Guide \&
Reference Manual. Addison-Wesley (fifth edition), 1986.

\endrefs



\end{document}