# PlanetMath graphics sandbox

## Primary tabs

Type of Math Object:
Data Structure
Major Section:
Reference
Groups audience:

## Mathematics Subject Classification

### picture request

Since this entry seems to be a hub of graphics activity, I'm
posting my request here.

I am working on an entry on basic methods of enumerative
combinatorics. Right now I'm working on the principle of
inclusion-exclusion. In its most basic form, this says that
$|S| + |T| = |S\cup T| + |S\cap T|.$
Intuitively this is true because if you mark each element of
$S$ with a daub of blue paint and then mark each element of
$T$ with a daub of red paint, then each element of $S\cup T$
will have at least one daub of paint on it, red or blue, and
each element of the intersection $S\cap T$ will have two daubs
of paint on it.

What I would like to include to illustrate this is a Venn diagram
showing the intersection of two circles, one marked $S$ and
one marked $T$. The components $S\setminus T$ and $T\setminus S$
each should have an x inside, while the intersection should have
two xs.

Is anyone willing or able to contribute such a picture?