Zobrazeno 1 - 10
of 48
pro vyhledávání: '"Starr, Jason Michael"'
Autor:
Starr, Jason Michael, Tian, Zhiyu
In this short note we give a characterization of smooth projective varieties of Picard number one that are separably uniruled but not separably rationally connected. We also give a sufficient condition involving the torsion order and the uniruling in
Externí odkaz:
http://arxiv.org/abs/1907.07041
For a smooth curve $B$ over an algebraically closed field $k$, for every $B$-flat complete intersection $X_B$ in $B\times_{\text{Spec}\ k} \mathbb{P}^n_k$ of type $(d_1,\dots,d_c)$, if the Fano index is $\geq 2$ and if $\text{char}(k)>\max(d_1,\dots,
Externí odkaz:
http://arxiv.org/abs/1811.02466
Autor:
Starr, Jason Michael
Kollar and Ruan proved symplectic deformation invariance for uniruledness of Kaehler manifolds. Zhiyu Tian proved the same for rational connectedness in dimension < 4. Kollar conjectured this in all dimensions. We prove Kollar's conjecture, as well a
Externí odkaz:
http://arxiv.org/abs/1803.06412
Autor:
Starr, Jason Michael
In his work extending rational simple connectedness to schemes with higher Picard rank, Yi Zhu introduced hypotheses for schemes insuring that the relative Picard functor is representable and is \'{e}tale locally constant with finite free stalks. We
Externí odkaz:
http://arxiv.org/abs/1706.09327
Autor:
Starr, Jason Michael
Intersection sheaves, i.e., the Deligne pairing, were first introduced by Deligne in the setting of Poincare duality for etale cohomology, and later in his work on the determinant of cohomology. Intersection sheaves were generalized from smooth schem
Externí odkaz:
http://arxiv.org/abs/1706.05573
Autor:
Starr, Jason Michael
The cohomological dimension of a field is the largest degree with non-vanishing Galois cohomology. Serre's "Conjecture II" predicts that for every perfect field of cohomological dimension $2$, every torsor over the field for a semisimple, simply conn
Externí odkaz:
http://arxiv.org/abs/1704.02932
Autor:
Starr, Jason Michael
Alex Waldron proved that for sufficiently general degree $d$ hypersurfaces in projective $n$-space, the Fano scheme parameterizing $r$-dimensional linear spaces contained in the hypersurface is nonempty precisely for the degree range $n\geq N_1(r,d)$
Externí odkaz:
http://arxiv.org/abs/1703.03294
Autor:
Roth, Mike, Starr, Jason Michael
We present a new perspective on the weak approximation conjecture of Hassett and Tschinkel: formal sections of a rationally connected fibration over a curve can be approximated to arbitrary order by regular sections. The new approach involves the stu
Externí odkaz:
http://arxiv.org/abs/0908.0096
Under suitable hypotheses, we prove that a form of a projective homogeneous variety $G/P$ defined over the function field of a surface over an algebraically closed field has a rational point. The method uses an algebro-geometric analogue of simple co
Externí odkaz:
http://arxiv.org/abs/0809.5224
Autor:
Starr, Jason Michael
Under a hypothesis on $k$, $d$ and $n$ that is almost the best possible, we prove that for every smooth degree $d$ hypersurface in $P^n$, the $k$-plane sections dominate the moduli space of degree $d$ hypersurface in $P^k$. Using this we prove ration
Externí odkaz:
http://arxiv.org/abs/math/0607133