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User:Lethe

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This is an old revision of this page, as edited by Feydey (talk | contribs) at 22:41, 26 March 2006 (Revert to revision 45266264 using popups). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Revision as of 22:41, 26 March 2006 by Feydey (talk | contribs) (Revert to revision 45266264 using popups)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)
File:Goya - Saturno devorando a su hijo.jpg
Saturn devours his children (Francisco de Goya, c. 1815).

To do list

/todo

Reference links

my questions

asked

math questions

answered

  • ]

reference

  1. Is there a general place for discussion of, complaints about, suggestions for all things LaTeX?
    1. Why can't Latex do \dotsc or other ams stuff (which ams stuff can't it do? all?)?
perhaps Misplaced Pages talk:TeX markup or m:Help talk:Formula, although it seems like there are more questions than answers there...
\dotsb= ⋯ {\displaystyle \dotsb }
\dotsc= … {\displaystyle \dotsc }
\dotsm= ⋯ {\displaystyle \dotsm }
'Cause Misplaced Pages uses only a subset of LaTeX. (I know this is not very satisfactory explanation.) Why is ⋯ {\displaystyle \cdots } (\cdots) and … {\displaystyle \ldots } (\ldots) not enough? Oleg Alexandrov 03:34, 13 July 2005 (UTC)

1 2 π i ∮ ⁡ f ( z ) z − a d z = f ( a ) {\displaystyle {\frac {1}{2\pi i}}\oint {\frac {f(z)}{z-a}}\,dz=f(a)} remember your \, for spacing

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subpages


tangent vectors on the sphere

Reminder:

χ ( S n ) = 1 + ( − 1 ) n {\displaystyle \chi (\mathbb {S} ^{n})=1+(-1)^{n}}

and by Poincaré-Hopf, there can be no nonvanishing vectors if the Euler characteristic doesn't vanish (confer hairy ball theorem). Thus, only for n odd are there nonvanishing vector fields. In this case, let

n + 1 = ( 2 m + 1 ) 2 4 a + b  where  0 ≤ b ≤ 3 {\displaystyle n+1=(2m+1)2^{4a+b}{\mbox{ where }}0\leq b\leq 3}

then there are 2+8*a−1 independent vector fields. Thus it follows that if n is 0, 1, 3 or 7, there are n independent vector fields so the corresponding tangent bundles are trivial. These also give constructions for the 4 normed division algebras.

gauge

The criterion I like is to say a 1-parameter group of symmetries is "physical" if its generator does not vanish by virtue of the equations of motion, and "gauge" if the generator does vanish when the equations of motion hold. If our symmetry is "gauge" we should mod out by it; if it's "physical" we should not.

-John Baez

Usually people don't bother to define "forgetful functor" very precisely - like pornography, you're just supposed to know a forgetful functor when you see it.

"Lethaeum ad fluuium deus euocat agmine magno, scilicet immemores supera ut conuexa reuisant rursus, et incipiant in corpora uelle reuerti"

failures of wikipedia

the password list debacle

Wikipedians, in their infinite wisdom, voted not to delete a page which exposed users' passwords, because the users in question were probably trolls. Developer Brion Vibber said this about it:

Nonetheless, this list was at best borderline with respect to our privacy policy. I deleted it as soon as I was made aware it was still here (I'd been under the impression it had been deleted within hours of originally being posted, and no one has contacted me or the developers team about it that I'm aware of). If the site admins here on en.wikipedia.org didn't remove it, that's a group failure and I'm rather disappointed.

--Brion Vibber, Chief Technical Officer, Wikimedia Foundation. 22:37, May 31, 2005 (UTC)

spreading misinformation via wikipedia

Viajero included the following line to the original version of the 1755 Lisbon earthquake article

"Priests of the inquisition roamed the city, rounding up "heretics" and hanging them on the spot for angering God"

It stayed in the article for years, spreading all over the Internet, and was eventually quoted in the Washington Post , and from there it was tracked down by some Catholic who knew it to be obviously false. This resulted in bad press for Misplaced Pages, and then he was asked by Jimbo himself where that information had come from, to which Viajero (who is an administrator and so a trusted member) apparently never replied.

Contributions

Pages by me

editcountitis

Edit count for Lethe

It appears some of my edits have been disappearing. I suppose that means they've been deleted?

I made my 1 edit here on en:wikipedia at 05:29, October 10, 2003 UTC.

I made my 1 000 edit here on en:wikipedia at 16:40, October 12, 2004 UTC.

I made my 2 000 edit here on en:wikipedia at 15:08, July 1, 2005 UTC.

I made my 3 000 edit here on en:wikipedia at 14:40, November 20, 2005 UTC.

I made my 4 000 edit here on en:wikipedia at 18:39, January 26, 2006 UTC.

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