Maths-Venn diagram

[AgeGap]

Saw this http://http://forums.randi.org/attachment.php?attachmentid=7884&d=1185914266
Is it correct? If not what should it be?

[AgeGap]

Bad link above.
http://forums.randi.org/attachment.php?attachmentid=7884&d=1185914266

[quixotecoyote]

It's wrong. Watch this space for a correction.

[AgeGap]

Got it. Two concentric circles. Middle with Explosives, Whole labled Sounds of explosions

[fls]

Got it. Two concentric circles. Middle with Explosives, Whole labled Sounds of explosions

If a tree explodes in a forest and there is no one to hear it....

Is the diagram directed at claims that "sound of explosion" = "explosion", or that "explosion" = "sound of explosion"? I'm thinking that under some circumstances the smaller circle is not fully contained within the larger, but I won't press the point if it's not relevant.

Linda

[quixotecoyote]

I was using the categories you posted earlier, which are not conducive to display in the manner you were looking for. The most accurate manner would be:
http://i49.photobucket.com/albums/f253/quixotecoyote/oneoffs/explosioncauses.jpg

because there is no unity in the sets you gave and between the two options they account for all possibilities.

Your concentric circle idea would need a label change, because explosives are not a subset of other [non-explosives] causes.

[AgeGap]

Didn't even think the above was an option. I have only got a little knowledge about Venn diagrams. Not on the O level syllabus.

[IvanOffalich]

I may be wrong, but don't the circles in a Venn Diagram have to overlap each other?

A quick search on Google took me to a Wikipedia page about Venn Diagrams. It showed interconnected circles as examples. The middle common area would show that say category A & B would have a middle ground sharing both properties. Say circle A was people who eat Chinese food every week. Circle B would be people who eat Italian food each week. The middle area, where the circles overlapped would be people who eat both each week.

I'm not sure if a Venn Diagram is the proper way to illustrate your point unless sound is coming from both explosions and other causes simultaneously.

[quixotecoyote]

Didn't even think the above was an option. I have only got a little knowledge about Venn diagrams. Not on the O level syllabus.

Well to the best of my knowledge, that's how you'd represent two sets with no commonalities. However, generally when you have that situation, you don't make a Venn diagram.

If there were other options involved, your first diagram would have been accurate. If your two subsets had been 'explosions' and 'popping transformers' or 'explosions' and 'building collapse' then you would have been correct initially.

But because you defined your second set as all remaining possibilities not in the first set, there can't be a third set involved.

[quixotecoyote]

I may be wrong, but don't the circles in a Venn Diagram have to overlap each other?

A quick search on Google took me to a Wikipedia page about Venn Diagrams. It showed interconnected circles as examples. The middle common area would show that say category A & B would have a middle ground sharing both properties. Say circle A was people who eat Chinese food every week. Circle B would be people who eat Italian food each week. The middle area, where the circles overlapped would be people who eat both each week.

I'm not sure if a Venn Diagram is the proper way to illustrate your point ]unless sound is coming from both explosions and other causes simultaneously.

He could have labeled the primary set in the intial diagram 'possible causes for the sound of an explosion at the twin towers', but then he's left with trying to get his two subsets to fill the entire circle without overlapping. Not something a Venn diagram can do easily.

eta:
Or he could have labeled the diagram: "Possible causes for explosions at sites of collapsing buildings. Then he could have 'explosives' and 'other causes' and had them overlap in the basic manner, showing that sometimes it's explosives, sometimes it's something else, and sometimes it's explosives and something else.

[blobru]

...
http://forums.randi.org/attachment.php?attachmentid=7884&d=1185914266

You might interpret the diagram as "Sounds of Explosions" [causes under investigation]: right circle = set "Explosives"; left circle = set [identified as] "Other Causes"; blue but outside both inner circles = set unidentified as either yet.

You're right this wouldn't be a good choice for a Venn Diagram, as there is no way the 'inner' sets could intersect / overlap, by definition.

If all the causes were ever identified, the two sub-sets would become [I]complementary: a sound falls within either one circle or the other, but not neither, and not both. (hope that's not confusing) :)

[Mangafranga]

But because you defined your second set as all remaining possibilities not in the first set, there can't be a third set involved.Why not? The third set can be- all the sounds of explosives which are neither explosives, nor other causes. This would be an empty set, however.

[AgeGap]

Why not? The third set can be- all the sounds of explosives which are neither explosives, nor other causes. This would be an empty set, however.
I starte off thinking, "I wish I knew more maths".Now I am glad I am ignorant. BTW my headache stated when unity was mentioned.

[quixotecoyote]

Why not? The third set can be- all the sounds of explosives which are neither explosives, nor other causes. This would be an empty set, however.

Yes, but how would you show that in a Venn Diagram. When using that kind of diagram, the space with nothing represented is the empty set.

[JoeTheJuggler]

I was using the categories you posted earlier, which are not conducive to display in the manner you were looking for. The most accurate manner would be:
http://i49.photobucket.com/albums/f253/quixotecoyote/oneoffs/explosioncauses.jpg

because there is no unity in the sets you gave and between the two options they account for all possibilities..
Where would you put something like a tape recording of the sound of an explosion caused by actual explosives?

You could argue for it being "other causes" (magnetic tape or whatever being read and sound coming from speakers), but you could also argue that it was caused by explosives.

[JoeTheJuggler]

I may be wrong, but don't the circles in a Venn Diagram have to overlap each other?
Not if you want to show disjointed sets.

The overlap would show that there is at least one thing that is a member of both sets.

[quixotecoyote]

Where would you put something like a tape recording of the sound of an explosion caused by actual explosives?

You could argue for it being "other causes" (magnetic tape or whatever being read and sound coming from speakers), but you could also argue that it was caused by explosives.

That's an issue of ill-defined sets, not overlapping sets. Once you specify what you mean by 'explosives' the question goes away.

[JoeTheJuggler]

That's an issue of ill-defined sets, not overlapping sets. Once you specify what you mean by 'explosives' the question goes away.
I agree.
The tape recording is definitely a member of one but not both sets.

The issue of definition goes back to what Linda said.

While your set up makes it more clear, the definition issue persists (in this case, I think the issue is the definition of "cause"--is the recorded sound caused by the electronics or by the sound that it originally recorded?)

[Mangafranga]

Yes, but how would you show that in a Venn Diagram. Easy.When using that kind of diagram, the space with nothing represented is the empty set.It already is represented.

[IvanOffalich]

Not if you want to show disjointed sets.

The overlap would show that there is at least one thing that is a member of both sets.

Thanks for clearing this up. As I said, I am not familiar with Venn Diagrams. The only ones I've seen are the overlapping kind. I wasn't sure if that was part of the definition or not. It would seem that it's not.

[quixotecoyote]

Easy.It already is represented.

You would need to elaborate in order to have this make sense.

[Mangafranga]

You would need to elaborate in order to have this make sense.You asked how would this set, which is empty, be represented in such a diagram. You then answered the question yourself by pointing out that "the space with nothing represented is the empty set."

[quixotecoyote]

You asked how would this set, which is empty, be represented in such a diagram. You then answered the question yourself by pointing out that "the space with nothing represented is the empty set."

Then that doesn't really get you anywhere then, does it?

[Mangafranga]

Then that doesn't really get you anywhere then, does it?I don't understand what this comment means, elaboration might be in order.

[quixotecoyote]

I don't understand what this comment means, elaboration might be in order.

I explained that all possibilities were included in two mutually exclusive sets.

You suggested a third that included the possibilities in neither [empty set].

I said that the space on the diagram with nothing in it is the empty set.

You noted it was already represented.

Given that I had just said that the empty space represented the empty set, it didn't really go anywhere.

[Mangafranga]

I explained that all possibilities were included in two mutually exclusive sets.

You suggested a third that included the possibilities in neither [empty set].

I said that the space on the diagram with nothing in it is the empty set.

You noted it was already represented.

Given that I had just said that the empty space represented the empty set, it didn't really go anywhere.The reason I noted it was already represented is because you asked me to show how it would be represented. I don't think we actually disagree on anything here, so I agree that this isn't going anywhere.

[quixotecoyote]

ah I was trying to figure out what you wee disagreeing with :D