The d-very ampleness on a projective surface in positive characteristic

1999 ◽  
Vol 187 (1) ◽  
pp. 187-199 ◽  
Author(s):  
Hiroyuki Terakawa
Keyword(s):  
Positive Characteristic ◽  
Projective Surface ◽  
Very Ampleness

scholarly journals Fibrations with moving cuspidal singularities

1991 ◽  
Vol 122 ◽  
pp. 161-179 ◽  
Author(s):  
Yoshifumi Takeda
Keyword(s):  
Algebraic Geometry ◽  
Characteristic Zero ◽  
Positive Characteristic ◽  
Closed Field ◽  
Projective Surface ◽  
Projective Curve ◽  
Smooth Projective Curve ◽  
Algebraically Closed Field ◽  
Smooth Projective Surface ◽  
Almost All

Let f: V → C be a fibration from a smooth projective surface onto a smooth projective curve over an algebraically closed field k. In the case of characteristic zero, almost all fibres of f are nonsingular. In the case of positive characteristic, it is, however, known that there exist fibrations whose general fibres have singularities. Moreover, it seems that such fibrations often have pathological phenomena of algebraic geometry in positive characteristic (see M. Raynaud [7], W. Lang [4]).

scholarly journals On Smooth Projective D-Affine Varieties

2020 ◽  
Author(s):  
Adrian Langer
Keyword(s):  
Positive Characteristic ◽  
Projective Surface ◽  
Affine Variety ◽  
Basic Tool ◽  
Smooth Projective Surface ◽  
Simply Connected

Abstract We show various properties of smooth projective D-affine varieties. In particular, any smooth projective D-affine variety is algebraically simply connected and its image under a fibration is D-affine. In characteristic 0 such D-affine varieties are also uniruled. We also show that (apart from a few small characteristics) a smooth projective surface is D-affine if and only if it is isomorphic to either ${{\mathbb{P}}}^2$ or ${{\mathbb{P}}}^1\times{{\mathbb{P}}}^1$. In positive characteristic, a basic tool in the proof is a new generalization of Miyaoka’s generic semipositivity theorem.

scholarly journals Numerical Criteria for Very Ampleness of Divisors on Projective Bundles Over an Elliptic Curve

1996 ◽  
Vol 48 (6) ◽  
pp. 1121-1137 ◽  
Author(s):  
Alberto Alzati ◽  
Marina Bertolini ◽  
Gian Mario Besana
Keyword(s):  
Elliptic Curve ◽  
Numerical Characterization ◽  
Projective Bundles ◽  
Very Ampleness

AbstractLet D be a divisor on a projectivized bundle over an elliptic curve. Numerical conditions for the very ampleness of D are proved. In some cases a complete numerical characterization is found.

scholarly journals ON ORDINARY ENRIQUES SURFACES IN POSITIVE CHARACTERISTIC

2020 ◽  
pp. 1-14
Author(s):  
ROBERTO LAFACE ◽  
SOFIA TIRABASSI
Keyword(s):  
Positive Characteristic ◽  
Enriques Surfaces

Abstract We give a notion of ordinary Enriques surfaces and their canonical lifts in any positive characteristic, and we prove Torelli-type results for this class of Enriques surfaces.

scholarly journals Physiological performance of Kazachstania unispora in sourdough environments

2021 ◽  
Vol 37 (5) ◽  
Author(s):  
Dea Korcari ◽  
Giovanni Ricci ◽  
Claudia Capusoni ◽  
Maria Grazia Fortina
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Environmental Factors ◽  
Positive Characteristic ◽  
Carbohydrate Source ◽  
High Osmolarity ◽  
Commercial Strain ◽  
Positive Properties ◽  
Nutritional Mutualism

AbstractIn this work we explored the potential of several strains of Kazachstania unispora to be used as non-conventional yeasts in sourdough fermentation. Properties such as carbohydrate source utilization, tolerance to different environmental factors and the performance in fermentation were evaluated. The K. unispora strains are characterized by rather restricted substrate utilization: only glucose and fructose supported the growth of the strains. However, the growth in presence of fructose was higher compared to a Saccharomyces cerevisiae commercial strain. Moreover, the inability to ferment maltose can be considered a positive characteristic in sourdoughs, where the yeasts can form a nutritional mutualism with maltose-positive Lactic Acid Bacteria. Tolerance assays showed that K. unispora strains are adapted to a sourdough environment: they were able to grow in conditions of high osmolarity, high acidity and in presence of organic acids, ethanol and salt. Finally, the performance in fermentation was comparable with the S. cerevisiae commercial strain. Moreover, the growth was more efficient, which is an advantage in obtaining the biomass in an industrial scale. Our data show that K. unispora strains have positive properties that should be explored further in bakery sector. Graphic abstract

scholarly journals Étale contractible varieties in positive characteristic

2014 ◽  
Vol 8 (4) ◽  
pp. 1037-1044
Author(s):  
Armin Holschbach ◽  
Johannes Schmidt ◽  
Jakob Stix
Keyword(s):  
Positive Characteristic

scholarly journals SUBALGEBRAS OF THE POLYNOMIAL ALGEBRA IN POSITIVE CHARACTERISTIC AND THE JACOBIAN

2011 ◽  
Vol 10 (04) ◽  
pp. 605-613
Author(s):  
ALEXEY V. GAVRILOV
Keyword(s):  
Principal Ideal ◽  
Positive Characteristic ◽  
Polynomial Algebra ◽  
Characteristic P ◽  
The Ideal

Let 𝕜 be a field of characteristic p > 0 and R be a subalgebra of 𝕜[X] = 𝕜[x1, …, xn]. Let J(R) be the ideal in 𝕜[X] defined by [Formula: see text]. It is shown that if it is a principal ideal then [Formula: see text], where q = pn(p - 1)/2.

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