In algebraic geometry, the Cartier isomorphism is a certain isomorphism between the cohomology sheaves of the de Rham complex of a smooth algebraic variety over a field of positive characteristic, and the sheaves of differential forms on the Frobenius twist of the variety. It is named after Pierre Cartier. Intuitively, it shows that de Rham cohomology in positive characteristic is a much larger object than one might expect. It plays an important role in the approach of Deligne and Illusie to the degeneration of the Hodge–de Rham spectral sequence.[1]
^Pierre Deligne; Luc Illusie (1987). "Relèvements modulo p2 et décomposition du complexe de de Rham". Inventiones Mathematicae. 89 (2): 247–270. doi:10.1007/BF01389078. S2CID 119635574.
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In algebraic geometry, the Cartierisomorphism is a certain isomorphism between the cohomology sheaves of the de Rham complex of a smooth algebraic variety...
with positive characteristic or more arithmetic structure, additional isomorphism types exist. For example, if 2 is invertible over the base, all group...
interactions with Cartier divisors, they play a central role in the study of algebraic varieties. Let (X, OX) be a ringed space. Isomorphism classes of sheaves...
geometry, a relative effective Cartier divisor is roughly a family of effective Cartier divisors. Precisely, an effective Cartier divisor in a scheme X over...
Picard group of a ringed space X, denoted by Pic(X), is the group of isomorphism classes of invertible sheaves (or line bundles) on X, with the group...
A reflexive module is one for which the canonical homomorphism is an isomorphism. A torsionless module is one for which the canonical homomorphism is...
abelian group with 1 its identity element. The logarithm is a group isomorphism of this group to the additive group of real numbers, R {\displaystyle...
bundle. The restriction from the divisor class group Cl(X) to Cl(U) is an isomorphism, and (since U is smooth) Cl(U) can be identified with the Picard group...
from the group of Cartier divisors to the Picard group Pic ( X ) {\displaystyle \operatorname {Pic} (X)} of X, the group of isomorphism classes of line...
the first Chern class is the isomorphism from the Picard group of line bundles on a variety X to the group of Cartier divisors modulo linear equivalence...
the pair ( Q , ℓ ) {\displaystyle (Q,\ell )} to Q. This morphism is an isomorphism on the open subset of all points ( Q , ℓ ) {\displaystyle (Q,\ell )}...
as an invertible sheaf. The canonical class is the divisor class of a Cartier divisor K {\displaystyle K} on V {\displaystyle V} giving rise to the canonical...
observation gives an isomorphism between Σ n {\displaystyle \Sigma _{n}} and Σ − n {\displaystyle \Sigma _{-n}} since there is the isomorphism vector bundles...
{\text{End}}({\widehat {G}})^{\text{op}}} . More categorically, this is not just an isomorphism of endomorphism algebras, but a contravariant equivalence of categories...
\mathrm {Pic} \ \mathbf {P} _{\mathbf {k} }^{n}=\mathbb {Z} } , and the isomorphism is given by the degree of divisors. The invertible sheaves, or line bundles...
dual morphisms fv: Bv → Av in a compatible way, and there is a natural isomorphism between the double dual Avv and A (defined via the Poincaré bundle)....
This association is a duality in the sense that there is a natural isomorphism between the double dual Avv and A (defined via the Poincaré bundle) and...
classification of (isomorphism classes of) complex line bundles by the first Chern class is a crude approximation to the classification of (isomorphism classes of)...
dimension. Let D ↪ X {\displaystyle D\hookrightarrow X} be an effective Cartier divisor. Then the normal bundle to it (or equivalently the normal cone...
{F}}(U)\to {\mathcal {F}}(V),\,f\otimes s\mapsto f\cdot s|_{V}} is an isomorphism. For each open affine subscheme U = Spec A {\displaystyle U=\operatorname...
between compact connected Lie groups and complex reductive groups, up to isomorphism. For a compact Lie group K with complexification G, the inclusion from...
to) local class field theory. More precisely the Artin map gives an isomorphism from the group GL1(K)= K* to the abelianization of the Weil group. In...