ACM sig-alternate document class -- How to create unnumbered theorem-like environments

Question

The command \newtheorem in the ACM sig-alternate document class takes two arguments. The first is the name of the environment and the second is the header, rendered in small-caps letters, that appears at the start of each occurrence of the construct.

Example MWE:

\documentclass{sig-alternate-05-2015}
\newtheorem{IP}{Interpretation Problem}
\newtheorem{axiom}{Axiom}
\begin{document}

% Copyright
\setcopyright{acmcopyright}


% DOI
\doi{10.475/123_4}

% ISBN
\isbn{123-4567-24-567/08/06}

%Conference
\conferenceinfo{PLDI '13}{June 16--19, 2013, Seattle, WA, USA}

\acmPrice{\$15.00}


\conferenceinfo{WOODSTOCK}{'97 El Paso, Texas USA}
\title{ABC}
\numberofauthors{2}
\author{
\alignauthor
ABC\\
\affaddr{Department of Computer Science and Engineering}
% 2nd. author
\alignauthor
XYZ\\
\affaddr{Department of Computer Science and Engineering}\\
}
\maketitle
\begin{abstract} Here is the abstract. 
\end{abstract}
\section{Intro}
This is the first section.
\begin{IP}
Given a set of services $S$ consisting $o$ operations, identify the subset of faulty operations...
\end{IP}
\begin{axiom}
contents...
\end{axiom}
\end{document}

By this, its appropriate number is appended and the text is set in italics.

I want to remove the numbering from this environment. How to do that?

Moreover, IEEE supports this. If we use

\newtheorem*{axiom*}{Axiom}

It would meet the need. However, the same is not working in ACM SIG template. Please suggest how to fix this issue.

The snapshot is attached for your reference. Have a look. How to remove the numbering from the newtheorem style environment.

Answer 1

Old ACM styles are old. Really old: they predate TeX3. One of their quirks is that they follow old LaTeX standards. Those did not allow unnumbered theorems (see Lamport's book). Another quirk is that they redefine some LaTeX constructions in many incompatible ways, so the use of packages became a risky business.

To make the long story short:

1. Mico's advice above works, but it might break in an unexpected place, so be careful.

2. I am happy to report that the new spiffy style acmart is released and going to become the official ACM style "really soon". I hope it will make authors' lives easier.

Answer 2

I suggest you add the following instructions before \documentclass{sig-alternate-05-2015}:

\RequirePackage{ntheorem}
\theoremheaderfont{\mdseries\scshape\hspace{\parindent}}
\theoremseparator{.}
\theorempreskip{1\baselineskip}

These instructions (a) load the ntheorem package and (b) make the appearance of theorem-like environments conform to what's provided by the sig-alternate-05-2015 document class.

Then, after the \documentclass instruction, you may write

\newtheorem*{IP}{Interpretation Problem}
\newtheorem*{axiom}{Axiom}

These instructions set up two unnumbered theorem-like environments.

---

A full MWE:

\RequirePackage{ntheorem}
\theoremheaderfont{\mdseries\scshape\hspace{\parindent}}
\theoremseparator{.}
\theorempreskip{1\baselineskip}
\documentclass{sig-alternate-05-2015}
\newtheorem*{IP}{Interpretation Problem}
\newtheorem*{axiom}{Axiom}
\begin{document}

% Copyright
\setcopyright{acmcopyright}
% DOI
\doi{10.475/123_4}
% ISBN
\isbn{123-4567-24-567/08/06}
%Conference
\conferenceinfo{PLDI '13}{June 16--19, 2013, Seattle, WA, USA}
\acmPrice{\$15.00}
\conferenceinfo{WOODSTOCK}{'97 El Paso, Texas USA}
\title{ABC}
\author{DEF}
\maketitle

\begin{abstract} 
Here is the abstract. 
\end{abstract}

\section{Intro}
This is the introduction.
\begin{IP}
Given a set of services $S$ consisting $o$ operations, identify the subset of \dots
\end{IP}

\begin{axiom}
Contents \dots
\end{axiom}

More text following the axiom \dots
\end{document}

Answer 3

You can use amsthm, provided you fix the proof environment, with a variation of http://tex.stackexchange.com/a/303810/4427 (my answer to another question of yours):

\documentclass{sig-alternate-05-2015}

\let\sigproof\proof\let\proof\relax
\let\sigendproof\endproof\let\endproof\relax

\usepackage{amsthm}

\let\proof\sigproof
\let\endproof\sigendproof

\makeatletter
\newtheoremstyle{sig}
  {}
  {}
  {\itshape}
  {}
  {\scshape}
  {.}
  {.5em}
  {#1\@ifnotempty{#2}{ #2}\thmnote{\quad(#3)}}% <--- changed!
\makeatother

\theoremstyle{sig}

\newtheorem{IP}{Interpretation Problem}
\newtheorem*{axiom*}{Axiom}

\setcopyright{acmcopyright}

\begin{document}

\section{Intro}
This is the first section.
\begin{IP}
Given a set of services $S$ consisting $o$ operations, 
identify the subset of faulty operations...
\end{IP}
\begin{axiom*}
contents...
\end{axiom*}
\end{document}