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1 vote

Nonequidimensional birational Mori contractions

Let $$ Y = \left\{ A = \left(\begin{smallmatrix} a_{11} & a_{12} & a_{13} \\ a_{21} & a_{22} & a_{23} \end{smallmatrix}\right) \right\} \cong \mathbb{A}^6. $$ Let also $$ X = \{ (A,...
Sasha's user avatar
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4 votes

Vector bundles on $\mathbb{P}^1$

Consider the exact sequence, $0\to E(-1)\to E\to E_p\to 0$, where the first map is just multiplication by $x$. Then $E_p$ is just the skyscraper sheaf at $p=(0,1)$. Taking cohomologies you get $0\to \...
Mohan's user avatar
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8 votes

Is the Gödel universe Wick rotatable?

$\DeclareMathOperator\SL{SL}$Clearly, as Robert Bryant indicates, it is Wick-rotatable to a different Lorentzian space. However, it is also Wick-rotatable to a Riemannian space, albeit negative ...
Sigbjørn Hervik's user avatar
1 vote

Solution to $a=e^t (t-r_1)(t-r_2)$ with Lambert $W$ function, where $r_1, r_2 $ are complex

This equation cannot be solved in terms of the Lambert $W$ function or any other known functions -- even if a, r1, and r2 are real, let alone complex. Here is what Mathematica says about this:
Iosif Pinelis's user avatar
8 votes

Is the Gödel universe Wick rotatable?

I may be misreading the sources that you list for the definition of Wick-rotatable, but, I believe that the following construction does fit that definition: According to the Wikipedia page that the ...
Robert Bryant's user avatar

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