# Jérémy Blanc

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bio website math.unibas.ch/~blanc location Basel age 32 member for 1 year, 11 months seen 14 mins ago profile views 1,189

I am working mostly in birational geometry, especially in studying Cremona groups.

# 354 Actions

 Apr15 comment Degree and quasi projective family What is the definition of $V_p$ ? Apr9 reviewed Approve suggested edit on Interpretation of the integral “with respect to a plane wave” in terms of Radon transform Apr9 reviewed Approve suggested edit on Inversion of Radon transform by incomplete data: specific case Apr9 reviewed Approve suggested edit on Choosing the order of Tikhonov regularization of an inverse problem Apr4 comment When is a blow-up of $\mathbb{P}^2$ a Mori Dream Space? Good reference. And in the article they explain that this works if $(K_X)^2>0$ or for some cases where $(K_X)^2<=0$. Apr4 comment When is a blow-up of $\mathbb{P}^2$ a Mori Dream Space? Another remark: if $k\ge 9$, then there are not always infinitely many $(-1)$-curves: take for example $k$ points on a line. A $(-1)$-curve distinct from the $k$ curves obtained is $C=dH-\sum a_i E_i$ and since $C^2=-1$, $CK=-1$, we have $3d-\sum a_i=-1$, and the intersection with the strict transform of the line is $0\le d-\sum a_i=-1-2d$. Hence, we have exactly $k$ $(-1)$-curves on the surface. Apr3 comment An affine singular surface Nice way of seeing it. For me it is "less familiar" but certainly "more familiar" for others. Hence it is good to have both ways. Apr3 comment When is a blow-up of $\mathbb{P}^2$ a Mori Dream Space? One remark: if $k\le 8$, then $-K_X$ is not always nef (think of $4$ points on a line for instance). What happens if $k\le 8$ and $-K_X$ is not ample? Is $X$ always a MDS? Is this just because $-K_X$ is big? Apr2 comment Compactification of the affine space with a del Pezzo surface Do you have some similar formulas when the singularities are mild? Apr2 reviewed Approve suggested edit on Induced graphs of cayley graph Apr2 comment Compactification of the affine space with a del Pezzo surface Thanks, nice remark. I was also thinking that smooth was too much. Apr2 asked Compactification of the affine space with a del Pezzo surface Apr2 comment NP-hard problems in linear algebra and real analysis Proving a conjecture is maybe a hard thing, but has nothing to do with the word "hard" of "NP-hard", as Noah S explained. Hence, talking about Riemann hypothesis in this context is quite weird. Apr2 answered An affine singular surface Apr1 comment Arithmetic property of a surface of general type If you take $P$ and $Q$ of small degree (for example of degree $1$), your surface $z^2=P(x)Q(y)$ is of course rational. That's why I asked what you assume on $P$, $Q$ to say that your variety is of general type. Apr1 comment Arithmetic property of a surface of general type How much is your degree $d$? If too small, the variety is certainly not of general type. Why do you think that you dont have rational curves on the surface? Apr1 reviewed Approve suggested edit on What groups have a second maximal subgroup below exactly four maximal subgroups? Mar30 reviewed Approve suggested edit on What groups have a second maximal subgroup below exactly four maximal subgroups? Mar30 comment Non existence of cyclic infinite linear algebraic groups Yes, I agree with Jason Starr, I still do not understand the details. Mar29 comment Hirzebruch's ICM talk At least the title means "complex manifolds"... but you probably know it since you tagged it :-)