Guide to LaTeX (4th Edition) (Tools and Techniques

\newtheorem{com}{Comment}
12.3. Further A M S-L AT E X packages 281
where the first argument is the name of the theorem type (here com) and
the second is the title that is printed when the theorem declaration is
invoked. For example,
\begin{com}
Theorem declarations can have any name.
\end{com}
produces the declaratory text
Comment 1. Theorem declarations can have any name.
In addition to the two mandatory arguments, the \newtheorem command
may have one of two optional ones. The complete syntax is
\newtheorem{type}[num like]{title}
or
\newtheorem{type}{title}[in counter]
where num like is the name of an existing theorem-like declaration which
is to be numbered in the same sequence as type, and in counter is a
counter name like chapter or section to reset the numbers of the type
declarations.
All this is standard L AT E X so far. The amsthm package adds the following
features.
• A \newtheorem* is provided that defines an unnumbered theorem
structure.
• Three predefined theorem styles are available:
plain in which the title and number are in bold face and the text
italic;
definition with title and number in bold face and the text in
normal font;
remark for title and number in italic and the text normal.
The desired style is activated by first issuing \theoremstyle{style};
all subsequent \newtheorem statements will have this style until a
new one is activated.
• A \swapnumbers can be issued to cause all following new theorem
types to have the numbers appear before the title, as 1 Comment.
• New theorem styles may be defined by the user by means of a
\newtheoremstyle command, or additional predefined styles may
be loaded with package options. Since this is fairly specialized and
complex, it is best to examine the example file thmtest.tex or read
the documentation in amsthm.dtx.