#### 9 comments on “Explaining the EU, Europe, the Euro, the eurozone”

1. Surreptitious Evil says:

And “What they will end up doing” is yet another disconnected set.

2. View from the Solent says:

SE, It’s likely that “What they will end up doing” will have some overlap with the “politically feasible”. But the intersection of the 3 will still be the null set.

3. Surreptitious Evil says:

I strongly suspect only with a time shift. What they will end up doing will be politically feasible at the time but would not be if proposed now.

4. Chris says:

And yet Krugman thinks that the USA needs an even bigger stimulus because the first one didn’t work. Same Venn diagram, I think.

5. Unimportant Quibbler says:

View from the Solent: I make this mistake all the time, and sometimes people pick me up on it. Back in the old days “null set” meant {} – the set with nothing at all in it. But these days the term “null set” has been appropriated by the measure-theory people (it now means a set that is “almost empty” in some sense, although may contain an infinite number of sparsely-distributed items) and {} is referred to exclusively as the “empty set”. I still slip into the old terminology by force of habit but I understand that financial mathematicians, probabilists etc would just titter at me for doing so.

6. David Gillies says:

UQ, by ‘almost empty’ you presumably mean a set that is nowhere dense*, i.e. of Lebesgue measure zero? I’ve always used the term ‘empty set’ for the set containing no objects and Ø or {} to refer to it (helpfully, Mathematica uses the latter convention.)

* e.g. the set of real numbers whose continued fraction coefficients do not yield Khinchin’s constant.

7. Unimportant Quibbler says:

DG – exactly correct, but I wished to remain non-technical as I doubted VftS would follow all this talk about Lebesgue measures

My teachers usually called the empty set the “null set”, and according to wikipedia (and the occasional older textbook I have hanging about) that used to be acceptable standard terminology. But no longer, since that’s been appropriated by the measure-theory people and no longer needs to be empty!

8. So Much For Subtlety says:

View from the Solent – “It’s likely that “What they will end up doing” will have some overlap with the “politically feasible”. But the intersection of the 3 will still be the null set.”

I am not so sure. I think that you need to add a picture of a bicycle pump labeled “Economic Pain” with three tubes leading to each balloon. At the moment there may be no overlap, or if there is, the overlap is empty. But as the pain increases, the three will eventually have an overlap containing at least one option.