Talk:Venn diagram
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I created a diagram Venn.jpg; I've contemplated the use of using a rectangle instead of a circle; I like circles. Because it may be a circle, and not a rectangle, would not make it any other diagram than a Venn diagram, however. And I doubt the diagram itself couldn't also be comprised of ellipses, and still be a Venn diagram. Which is my point. They're ellipses. It's not a historic representation of what John Venn himself drew; it is a Venn diagram. But it got deleted. Charles R. Kiss, Sept. 15, 2006
Contrary to what Poor Yorick writes below, the key difference between Venn and Euler diagrams is this - Venn diagrams explicitly represent the universe of possibilities by enclosing all the circles in a rectangle. This was Venn's key innovation. While it may seem trivial to us, it took mankind 2300 or so years (since Aristotle first wrote about logic) to do this, and it has had a far-reaching consequence: For the first time the complement of a set could be readily represented. Indeed, the graphic at the top of the page does not enclose the three circles in a universe box, and so is NOT a Venn diagram. Someone with better graphic skills than I should fix this diagram to make it a Venn diagram. Peter McBurney, 2006-05-28.
I drew these using jave.de and I'm aching for the same kind of graphical draw tool as found over at twiki, the twikidraw...I've raised the idea at the village pump... just finding a java person that knows enough about xml to write to the expat library in php...that's all ;) dennisdaniels
I just came looking for the answer to this question - are there sets of sets that cannot be represented by a 2D venn diagram? If so, how about if you extend the diagram to more than 2 dimensions? If somebody knows the answer, it should be included in the article, I think. -- Khendon 10:08 Sep 30, 2002 (UTC)
What's the difference between a Venn diagram and an Euler diagram? The article doesn't even hint at that. Both of the diagrams shown are Venn diagrams, as I have alwasy understood the term. Are they also both Euler diagrams? Michael Hardy 23:57 4 Jul 2003 (UTC)
- They're pretty much the same, except for the name. Mathematicians felt sorry for John Venn, so they named it after him. It's in the article and external link. Poor Yorick 00:04 5 Jul 2003 (UTC)
The page could use some mathematical markup. Like: A is a proper subset of B is written as: A (a rotated U) B, someone know how to make those symbols? BL 19:04, 7 Sep 2003 (UTC)
[edit] Anthony Edwards link
I don't think it links to the right Mr. Edwards. T0pem0 11:30, 14 Apr 2004 (UTC)
I am in a Probability Theory class.. and today was like the 3rd day of class. We were talking about Venn Diagrams, and I swear I heard the professor say
"Those are venn diagrams and I encourage you to use them when you think about sex"
So I'm sitting in class, trying to figure out how Venn Diagrams can be applied to sex before I come to the realization that he said "SETS", not sex. Oh well, so much for math being frightfully interesting.
[edit] A cartesian variation on Edwards diagrams
Edwards-diagrams are nice but not easy to draw. This on can be drawn on a grid, (with gray code in one collumn). See: http://home.versateladsl.be/vt649464/VenGray5.pdf Feel free to use it. Perhaps it exists already somewhere, I don't know.--Bleuprint (talk) 05:27, 8 February 2008 (UTC)
[edit] merge from euler diagram
I'm fairly sure these are one and the same, as discussed above. I think Euler diagram should redirect to here and a note made on name variation. There may be some content in Euler diagram worht keeping. --Salix alba (talk) 18:52, 18 January 2006 (UTC)
- It looks like Venn diagrams are subsets of Euler diagrams, not the other way around, so it'd have to be merged into Euler diagram, which would be a bad idea because Euler diagrams aren't as well-known. --AySz88^-^ 03:14, 19 January 2006 (UTC)
Yes there does seem to be some confusion. At [Stanford Encyclopedia of Philosophy] they mention Venn's Primary diagrams, which are what we are calling Venn diagrams. It would be good to make the destinction clear. I've a feeling some people do refer to Euler diagrams as Venn diagrams and we should make this clear. --Salix alba (talk) 17:17, 19 January 2006 (UTC)
[edit] Johnston Diagrams
The pictures given for these are all said to be Edwards-Venn diagrams on their respective pages, and the page on A. W. F. Edwards has the picture of the six-set one with the caption "Six-set Edwards-Venn diagram". Are they the same thing, or the wrong graphic? --Nucleusboy 23:50, 31 January 2006 (UTC) Check the article now especially the review of cogwheels, that should clarify your question. --Salix alba (talk) 03:00, 1 February 2006 (UTC)
[edit] Similar diagrams
I don't think the Euler, Johnstone etc. should be on the page as it stands, since they are not Venn diagrams - at most they should be wikilinked from a See Also section or similar. — SteveRwanda 12:49, 24 March 2006 (UTC)
[edit] Intersection or Union
I think there may be a mistake in the following sentence :
The combined area of sets A and B is called the union of sets A and B. The union, in this case, contains all things which either have two legs, fly's, or both.The overlaping circles implies that the union of the two sets is not empty - that, in fact, there are creatures that are in both of the orange and blue circles.
In set theory, the union of A and B is every element that belongs to A or that belongs to B, but the overlaping circles defines elements that belong to A and to B, that its intersection.
Isn't it ?
Zejames 21:06, 23 May 2006 (UTC)
[edit] Tools for drawing Venn diagrams
It would appear as if the drawing feature in MS Office (MS Powerpoint) only creates correct Venn diagrams for up to 3 sets. Maybe this is an important distinction among other tools listed?
[edit] Sven diagrams?
Some people erroneously call them Sven diagrams, this term appears to have originated in certain parts of Montreal. Surely this is a joke? Either way, I'm not sure it's much of an issue, as most people learn about them in math class from teachers who know the correct term, so I can't imagine it's a widespread error. That sentence ought to be deleted if it remains unsourced. OneVeryBadMan 15:05, 19 July 2006 (UTC)
[edit] Classroom use ?
Not sure about the appropriateness of this section, though I like the attempt to address a more general audience - I find this article a little too math text book-y. More importantly though: I've never seen the "three column" approach instead of overlapping circles (and I can't picture how it would work - how do you represnt a u b u c? Or more than three sets?). And the "compare and contrast two items" [my emphasis] piece doesn't make sense to me. Is there a citation for this? Is it common to a particular educational approach? Is it just the general new approach to teaching that I'm too old to remember :-) ? --SiobhanHansa 01:10, 16 August 2006 (UTC)
I am not sure about the relevance of the Indian classrooms point, I could say that in New Zealand they teach them using powerpoint slides, but really what is the relevance. Nzv8fan 08:25, 3 June 2007 (UTC)
- I've gone ahead and removed that sentance. It wasn't relevent, and it was just akward. Kopophex (talk) 12:22, 7 January 2008 (UTC)
[edit] too technical tag
i removed the tag. the article has undergone considerable revision since the tag was removed. if you feel that the tag still belongs, feel free to put it back but please make some specific suggestions about what could be improved. thanks. Lunch 04:53, 24 September 2006 (UTC)
[edit] All monkeys are primates.
This Venn diagram from The Fallacy Files is given to illustrate the proposition "All monkeys are primates", where S is the subject (Monkeys) and P is the predicate (Primates).
http://img219.imageshack.us/img219/6671/picture1be5.png
What I don't understand is why there is this high-lighted red area where S and P do not overlap? Doesn't this imply that there are monkeys which are not primates? Isn't this A-type proposition better represented with a Euler diagram, having S inside (as a subset of) P? Or does red represent emptiness?
What am I missing?
- In that case I think the the red indicates emptyness, i.e. the disallowed elements. Yes you could use an Euler diagram which indicates the concept better. The ven diagram is useful as it explicity shows whats not allowed. --Salix alba (talk) 17:06, 30 September 2006 (UTC)
[edit] Error ?
Shouldn't the sentence "Mosquitos have six legs, and fly, so the point for mosquitos would be in the part of the blue circle which does not overlap with the orange one." paragraph 2 read ". . . the part of the blue circle which overlaps with the orange one . . ." —Preceding unsigned comment added by 58.111.208.201 (talk) 10:47, 8 October 2007 (UTC)
- No. The area where the blue and orange circles overlap contains those living creatures that can fly and have two legs. Mosquitoes can fly but do not have two legs, so they are outside the orange circle. --Lambiam 13:56, 8 October 2007 (UTC)
[edit] Images at the top are misleading
Just looking at the top 3 pictures, one could be forgiven for thinking that we are talking about subtractive colours. Can we please have normal circles? Also what happened to the dots inside the circles representing elements of the sets? I can't believe there is no example of that in the article. These solid discs bring no added value and are actually misleading/confusing. Thanks. 83.67.217.254 (talk) 21:04, 1 March 2008 (UTC)
