This is a small point (some would say pedantic) concerning the following diagram that currently appears on the About page of Stack Overflow and other Stack Exchange sites:

Figure 1

(This is an attachment. Here is the original link.)

It is labeled as a Venn diagram, both by the name of the file (venn-diagram.png) and the alt attribute (Venn diagram: Wiki, Digg/Reddit, Blog, Forum), but this is a mislabeling because a Venn diagram must by definition show all possibilities, and the following possibilities are not represented:

  1. Just Wiki and Forum
  2. Just Digg/Reddit and Blog

A simple solution would be to remove the word "Venn" from the labels; alternatively, we could redraw as an actual Venn diagram, which I'm guessing would not be a popular choice due to aesthetics and clarity of communication. Alternatively, we could just decide that nobody really cares and leave everything the way it is.


UPDATE: Thanks everyone for the responses. I added strike-through above, since @John Gardner's answer shows my guess was wrong. I'll wait another day or so and then accept an answer based on votes (let's say, the answer must have at least two more votes than any other answer), unless someone tells me that's not proper procedure for these types of questions.

UPDATE 2: I've decided not to use votes to determine which answer to accept. The main reasons are (1) votes speak for themselves, and (2) votes can change after an answer has been accepted. I initially thought to use votes primarily because my question involves aesthetics, and I think it reasonable to assume that votes reflect what is most aesthetically pleasing to the community. However, the question is not purely aesthetic, so that reasoning does not fully apply here.

  • 2
    Wow, a downvote? Why? My impression of this community is that people are generally polite and civil. Getting a downvote with no comment and no answer goes against my expectation here. Commented Dec 10, 2010 at 10:13
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    Down-votes on meta have the additional meanings of "I disagree" and "this is not a problem" (amongst others) as well as the normal "unclear or not useful".
    – ChrisF Mod
    Commented Dec 10, 2010 at 10:33
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    I don't think the construction for all sets would look bad, in fact it would closely resemble a rainbow. Just add a unicorn and call it a job well done.
    – user50049
    Commented Dec 10, 2010 at 11:45
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    We need more heroes like you
    – juan
    Commented Dec 10, 2010 at 12:40
  • 6
    NOOOOO!!! Stack Overflow is built on a LIE! A LIE!!! Commented Dec 10, 2010 at 18:02
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    If this gets fixed before every other [bug] and [feature-request] is closed we've got problems Commented Dec 10, 2010 at 18:20
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    +1 just because it never occurred to me how that basic property of Venn diagrams would play out with >3 sets
    – Brad Mace
    Commented Dec 10, 2010 at 20:37
  • This page is hilarious! +1 for funny. Commented Dec 12, 2010 at 3:36
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    I know the diagram is gone now, but they could have just changed the label to Euler Diagram although the size of #3 in this euler diagram is pretty small Commented Mar 1, 2013 at 21:13

4 Answers 4


The circles just need to be ellipses and repositioned:


  • 18
    +1 I've been ensmartened by your picturizing
    – Brad Mace
    Commented Dec 10, 2010 at 20:38
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    i'm kist glad i could contribumarate. Commented Dec 10, 2010 at 20:52
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    That is bizarrely attractive Commented Dec 10, 2010 at 20:54
  • Initially I said this is the technically correct Venn diagram for the sets; but when trying to draw it myself, I realised the definition of each set is partly subjective; so that is up for debate. Then there is the second debate re its accuracy, as in, does SO fit in exactly where the asterisk is ? I am new here, so I don't know. +1 for the best attempt so far. Commented Dec 12, 2010 at 2:26
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    i think SO being the asterisk is the ideal of where SO wants to be. right now i think its "blog" section of the venn is much smaller than it could be. Commented Dec 13, 2010 at 19:36

Who said it is not a Venn Diagram? You think it's not just because the 2D projection is done badly. :)

alt text

  • 25
    that background hurts my brain Commented Dec 10, 2010 at 20:53
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    That background looks like brains. Commented Dec 10, 2010 at 21:03
  • 17
    That background is my brain
    – jcolebrand
    Commented Dec 10, 2010 at 22:09
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    Did you steal that background texture from Descent? I could swear I've flown through this tunnel
    – Brad Mace
    Commented Jul 8, 2011 at 4:18

You are right.

And you are the first in almost 28 months of existence that I have seen complaining about it.

But hopefully we can agree that this is not a showstopper. Just a slight annoyance.

  • 77
    I disagree. STACK OVERFLOW IS HEREBY CANCELLED. Commented Dec 10, 2010 at 10:41
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    Hahaha, first day at SO and I already managed to close the entire site. I wasn't really complaining or even annoyed, just thought it might make the site look more professional if more of the little details were in order. A typo report, basically. Commented Dec 10, 2010 at 11:09
  • Hmm there was a @martin who suggested adding the low-priority tag, which I have done (martin's comment is now deleted)... there are only 5 questions total with that tag though, I was expecting a larger number. Commented Dec 10, 2010 at 11:18
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    @Mitch: be careful about labeling this "a typo report, basically", lest Jeff personally come to your house and bludgeon you to death with a giant John Venn.
    – ЯegDwight
    Commented Dec 10, 2010 at 12:21
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    @Jeff Atwood - you have an obvious bug in cancellation routine. I can still access and post to SO. Should I post that failure to cancel as a new bug on MSO?
    – DVK
    Commented Dec 10, 2010 at 13:08

You are absolutely right. For a technical site, it is not pedantry.

There is a big problem in the industry in general, with terms that are clearly defined (don't waste time looking at wiki for definitions!), being used in loose ways or outside the specified context. This has an impact on newcomers, who learn the meaning of the term from the loose usage and poor diagrams.

No offence to Jeff, obviously, because the intention was great, but these diagrams labelled as, and linked to, Venn Diagrams, are not Venn Diagrams either.

As professionals, supporting a site "for professionals and enthusiast programmers", I think we should maintain correct usage of all the technical terms we use. The SO pages are full of people arguing the definition of terms; an act that people experienced in the subject simply do not do; and only people who have just read the definition, and have no experience, do. They speculate about their meanings and argue about their different specualtions ... all while not understanding the term.

If we are precise in the usage of technical terms, it will improve the quality of the site no end, over the long term. And therefore the relevance. if we aren't, then nothing changes: the site remains full of discussions among beginners who have no actual experience with the terms they are discussing. Another wiki, bloated and full of contradicting posts.

Getting back to what we should do about. There are four options:

  1. Use a Correct Venn Diagram
    If you draw it correctly, most people won't understand them (note bemace's comment); it leads to a learning experience (good thing), which is a tangent that has nothing to do with the subject (bad thing). Likewise, I do not use Venn diagrams when teaching SQL, joins, etc because drawn correctly, they are inadequate for the purpose.

  2. Remove the Diagram
    Undesirable, because then the graphic that conveys so much is gone, and we have to supply the 1,000 words in its place.

  3. Use Existing Diagram but Correct the Label
    That has some merit, in the sense that these simplistic, incorrect diagrams are everywhere, and people generally understand them; it conveys what we are trying to convey. The demerit is of course that SO perpetuates the incorrect usage (refer above) and thus diminishes our technical relevance. That can be mitigated by the choice of label: something like "Here's a { simplified | simplistic | partial } Venn diagram showing where we sit in relation to others sites".

  4. Invite People to Produce a Better Graphic
    Probably the best option, but it might take some time. See my comment on John Gardner's graphic.

I vote for implementing (3) right away, on the basis that it is the most sensible. And advertise (4) with a bounty.

Last, I do not see the value is choosing the most popular answer, you asked a question. By changing that in your edit, you have made it a popularity or presentation contest and it takes away from the original question. I suggest you choose the response that answers your original question the most or the best, and vote for the responses in which you learned something.

  • Thanks for the thoughtful reply. Seems to me that (a) Jeff's diagrams on SQL joins are Venn diagrams, it's just that the coloring makes the contours hard to see; (b) @John Gardner's diagram is a viable way to fulfill options (1) and (4) in your list simultaneously. Regarding how to accept an answer, your points have persuaded me to reconsider the matter, and I will update the question momentarily to reflect this. Commented Dec 12, 2010 at 3:13
  • @Mitch: Thanks. a) I am new to the site, I need some re-assurance that Jeff will not be affronted by us discussing the flaws in his post; then, I will post details b) Agreed. My point is, the confirmation of the sets and discussion re where SO fits, will take time. Commented Dec 12, 2010 at 11:39

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