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Re: Venn diagrams?

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  • Subject: [mg118269] Re: Venn diagrams?
  • From: Murray Eisenberg <murray at math.umass.edu>
  • Date: Tue, 19 Apr 2011 06:57:23 -0400 (EDT)

The "mathy" way to say it is simply that the areas should be 
proportional to the number of objects!

I might add that how to draw Venn diagrams is a delicate issue of 
graphics design: how to shade or color the individual circles and how to 
shade or color their various intersections. Fairly straightforward a 
decision with just two sets (and their intersection) being represented, 
but getting more difficult with three and even thornier with four.

As I recall, it's not yet a closed question how to construct a Venn 
diagram for larger numbers of sets (where, as always, you want them "in 
general position"). Of course with known sizes of the sets, it's a 
different matter.

On 4/18/2011 6:50 AM, dantimatter wrote:
> What I meant by 'to scale' is probably best explained with an example:
>
> Imagine that group A contains 40 objects, group B contains 30 objects, and
> the intersection of A and B contains 27 object.  In this case I would really like for the circle representing B to be 75% of the size of the circle representing A, and 90% of B to be overlapped by A.
>
> (There is probably a more 'mathy' way to say this, but I'm not sure what that is.  Sorry about that.)
>
> Thanks!
>

-- 
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305


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