In latex-mode it'd be good if \pagebreak[0] was a paragraph separator,
as for example

Blah blah         \ pagagraph
blah blah.        /
\pagebreak[0]
\begin{align}
...

An unconditional \pagebreak is already a separator, but not when an
optional arg [0] or [3] etc.

Perhaps digits and brackets like below.  Only some of the "space" "skip"
and "page" commands matched take optional args like this, but allowing
for all shouldn't hurt.

2014-11-12  Kevin Ryde  <user42_kevin@yahoo.com.au>

	* textmodes/tex-mode.el (latex-mode): In paragraph-separate allow
	optional argument [0] etc for \pagebreak[0]