[Blindmath] set notation in LaTeX

[Roopakshi Pathania]

Hi Prof. Stacey,

On Wed, 1/26/11, Andrew Stacey <andrew.stacey at math.ntnu.no> wrote:
> On Tue, Jan 25, 2011 at 09:12:20PM
> -0800, Roopakshi Pathania wrote:
> 
> > subset: \subset
> > The cup turned to the right side.
> > super set: \supset
> > The cup turned to the left side.
> > proper subset: \subseteq
> > Notice that here the short for equal is added to
> indicate a proper subset.
> 
> I think that you've gotten those two the wrong way
> around.  The symbol
> generated by \subseteq is a "cup" turned on its side (open
> side to the right)
> with a line underneath.  The line underneath makes the
> bottom of the cup look
> like an equals sign so the interpretation of "A \subseteq
> X" is "A is a subset
> of X which can be equal to X".  The unadorned symbol,
> generated by \subset, is
> actually ambiguous in meaning as it is sometimes
> interpreted to mean "A is
> a subset of X which can be equal to X" and sometimes "A is
> a proper subset of
> X, so cannot be equal to X".  Thus \subseteq, and its
> counterpart \subsetneq,
> are used when one wishes to resolve this ambiguity merely
> by symbols.  Often
> a text will explain that \subset means "any subset" or
> "proper subset" since
> the ambiguity exists.  If no explanation is given then
> it is safest to assume
> that \subset means **any** subset, which includes the whole
> set.
> 
> (For what it is worth, Wikipedia agrees with me on this
> one:
> http://en.wikipedia.org/wiki/Subset )

Thanks for correcting me. But I did say that \subset is a cup turned to the right side, which in my hurried explanation meant that the cup's open "mouth" is to the right side.
Of course you are right about the \subseteq symbol.

> Whilst I'm on this topic, may I point out http://tex.stackexchange.com for
> TeX/LaTeX questions.

I think the issue people face here is what question may be too unimportant for the forum?