<theorem> – (mathematical) theorem etc.

Attributes:

countlike

other theorem's class name, or "(none)", or "(global)"

layout

"plain" (default), "definition", or "remark"

xml:lang

human language (inherited)

id

unique name (identifier)

style/class

style properties and class (e.g. for CSS)

Possible Contents: heading?, subject?, (Text | inline element | block element)*

Description: Inserts a (mathematical) theorem, corollary, lemma, definition, or a remark, a note, an exercise, or an example. It is allowed everywhere where you could insert a floating figure.

For this element, the class attribute is vital. It is interpreted as the kind of the theorem. e.g., you could say

<theorem class="Remark">A short mathematical remark.</theorem>

If class is omitted a default is used.

The countlike contains another <theorem> class with which the current one should share numbering. Otherwise, every <theorem> class gets its own counting. For example,

<theorem class="Corollary"
  countlike="Lemma">A short mathematical corollary.  If
  it's corollary number 4, the next lemma will have
  number 5.</theorem>

If you want to suppress counting, set countlike to "(none)". If you don't want to have the chapter number included into the theorem number, set countlike to "(global)".

Special effects

The name of the theorem is the same as its class. If you want another name, include a <heading> element.

Within <subject>...</subject>, you can include e.g. a special name for the theorem. This is printed within brackets after the word “Theorem” (or whatever).

Example:

     <theorem class="Korollar">
       <heading>Corollary</heading>
       <subject>Streetmentioner's Corollary</subject>
       A short mathematical corollary.</theorem>

With the layout attribute, you can choose another style. Predefined are the AMSTeX styles "plain", "definition", and "remark". If you want to add another one, you have to give its definition in a LaTeX package.

Important: Only the very first occurrence of a certain <theorem> class is allowed to have <heading>, countlike, or layout.