# [NTG-context] bug with glue and spaces in formulas?

Wed Nov 10 19:44:49 CET 2004

Hi Hans and all Contexters,

While discussing with David Munger about the Steps macros he wrote
for presentations in ConTeXt (see the thread \presentationstep), we
noticed that there seems to be a problem with "white spaces" or glue
around some "binary operators" such as +, - and =.
Please see the result of the following sample.

Best regards: OK

%%%% begin file test-glue.tex
\starttext
This is to verify how the space, or glue, is controlled in \ConTeXt.

First some binary operators $\in$'', $+$'', $-$'' and $=$''
without grouping braces:
\placeformula[eq:plain]
\startformula
x\in \Omega \subset {\Bbb R}^N,\quad\quad -\Delta u + u -u^3 = f.
\stopformula
Next the same with braces
\placeformula[eq:braces1]
\startformula
x{\in} \Omega {\subset} {\Bbb R}^N,\quad\quad {-}\Delta u {+} u {-u^3} {=} f.
\stopformula
Note how the spaces around the signs $\in$, $+$, $-$ and $=$ have
shrinked. The problem seems to appear when these are actually binary
operators (that is $+1$ and ${+}1$ give the same result, while
$1+2=3$ is different from $1{+}2{=}3$).

I haven't tried all such binary operators, but it seems that this
happens with all of them: compare $A \cap B$ and $A{\cap}B$, or
$A\cup B$ and $A{\cup}B$.

\stoptext
%%%%% end file test-glue.tex