scholarly journals The affine part of the Picard scheme

2009 ◽  
Vol 145 (2) ◽  
pp. 415-422 ◽  
Author(s):  
Thomas Geisser

AbstractWe describe the maximal torus and maximal unipotent subgroup of the Picard variety of a proper scheme over a perfect field.

2021 ◽  
Vol 157 (10) ◽  
pp. 2338-2340
Author(s):  
Thomas Geisser

Abstract We give a corrected version of Theorem 3, Lemma 4, and Proposition 9 in the above-mentioned paper, which are incorrect as stated (as was pointed out by O. Gabber).


1987 ◽  
Vol 107 ◽  
pp. 63-68 ◽  
Author(s):  
George Kempf

Let H be the Levi subgroup of a parabolic subgroup of a split reductive group G. In characteristic zero, an irreducible representation V of G decomposes when restricted to H into a sum V = ⊕mαWα where the Wα’s are distinct irreducible representations of H. We will give a formula for the multiplicities mα. When H is the maximal torus, this formula is Weyl’s character formula. In theory one may deduce the general formula from Weyl’s result but I do not know how to do this.


2003 ◽  
Vol 266 (1) ◽  
pp. 87-101 ◽  
Author(s):  
Rosali Brusamarello ◽  
Pascale Chuard-Koulmann ◽  
Jorge Morales

Author(s):  
Zsolt Patakfalvi ◽  
Maciej Zdanowicz

AbstractWe prove that smooth, projective, K-trivial, weakly ordinary varieties over a perfect field of characteristic $$p>0$$ p > 0 are not geometrically uniruled. We also show a singular version of our theorem, which is sharp in multiple aspects. Our work, together with Langer’s results, implies that varieties of the above type have strongly semistable tangent bundles with respect to every polarization.


1995 ◽  
Vol 38 (4) ◽  
pp. 390-395 ◽  
Author(s):  
S. M. Bhatwadekar ◽  
K. P. Russell

AbstractLet k: be a perfect field such that is solvable over k. We show that a smooth, affine, factorial surface birationally dominated by affine 2-space is geometrically factorial and hence isomorphic to . The result is useful in the study of subalgebras of polynomial algebras. The condition of solvability would be unnecessary if a question we pose on integral representations of finite groups has a positive answer.


2011 ◽  
Vol 7 (3) ◽  
pp. 315-318 ◽  
Author(s):  
Qian-nan Wu ◽  
Ya-dong Xu ◽  
Huan-yang Chen
Keyword(s):  

2013 ◽  
Vol 9 (1) ◽  
pp. 90-93 ◽  
Author(s):  
Mohammad Mehdi Sadeghi ◽  
Hamid Nadgaran ◽  
Huanyang Chen

Author(s):  
Günter Harder

This chapter shows that certain classes of Harish-Chandra modules have in a natural way a structure over ℤ. The Lie group is replaced by a split reductive group scheme G/ℤ, its Lie algebra is denoted by 𝖌ℤ. On the group scheme G/ℤ there is a Cartan involution 𝚯 that acts by t ↦ t −1 on the split maximal torus. The fixed points of G/ℤ under 𝚯 is a flat group scheme 𝒦/ℤ. A Harish-Chandra module over ℤ is a ℤ-module 𝒱 that comes with an action of the Lie algebra 𝖌ℤ, an action of the group scheme 𝒦, and some compatibility conditions is required between these two actions. Finally, 𝒦-finiteness is also required, which is that 𝒱 is a union of finitely generated ℤ modules 𝒱I that are 𝒦-invariant. The definitions imitate the definition of a Harish-Chandra modules over ℝ or over ℂ.


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