Boas Erez | Université Bordeaux (original) (raw)

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Papers by Boas Erez

Research paper thumbnail of Forme Trace et Ramification Sauvage

Proceedings of The London Mathematical Society, 1990

Research paper thumbnail of The hermitian structure of rings of integers in odd degree abelian extensions

Journal of Number Theory, 1992

Research paper thumbnail of Riemann-Roch type theorems for schemes with a finite group action

Research paper thumbnail of Tame actions of group schemes: integrals and slices

Duke Mathematical Journal, 1996

Research paper thumbnail of Riemann-Roch type theorems for arithmetic schemes with a finite group action

Journal Fur Die Reine Und Angewandte Mathematik, 1997

Research paper thumbnail of Twists of symmetric bundles

We establish comparison results between the Hasse-Witt invariants w_t(E) of a symmetric bundle E ... more We establish comparison results between the Hasse-Witt invariants w_t(E) of a symmetric bundle E over a scheme and the invariants of one of its twists E_{\alpha}. For general twists we describe the difference between w_t(E) and w_t(E_{\alpha}) up to terms of degree 3. Next we consider a special kind of twist, which has been studied by A. Fr\"ohlich. This arises from twisting by a cocycle obtained from an orthogonal representation. We show how to explicitly describe the twist for representations arising from very general tame actions. This involves the ``square root of the inverse different'' which Serre, Esnault, Kahn, Viehweg and ourselves had studied before. For torsors we show that, in our geometric set-up, Jardine's generalization of Frohlich's formula holds. The case of genuinely tamely ramified actions is geometrically more involved and leads us to introduce a ramification invariant which generalises in higher dimension the invariant introduced by Serre for curves.

Research paper thumbnail of On the <img src="/fulltext-image.asp?format=htmlnonpaginated&src=PP0U0M22EE306ABU_html\" border="0" alt="$\epsilon$" />-constants of arithmetic schemes

Mathematische Annalen, 1998

Research paper thumbnail of Hasse–Witt invariants of symmetric complexes: an example from geometry

Comptes Rendus Mathematique, 2002

ABSTRACT Jardine has defined Hasse–Witt invariants for symmetric bundles over schemes. This defin... more ABSTRACT Jardine has defined Hasse–Witt invariants for symmetric bundles over schemes. This definition can be extended to symmetric complexes, that is symmetric objects in the derived category of bounded complexes of vector bundles over a scheme. In this Note we show how one can use these generalized invariants to give a neater proof of a comparison result on Hasse–Witt invariants of symmetric bundles attached to tame coverings of schemes. To cite this article: P. Cassou-Noguès et al., C. R. Acad. Sci. Paris, Ser. I 334 (2002) 839–842.

Research paper thumbnail of Twists of symmetric bundles

Proceedings of The London Mathematical Society, 2007

We establish comparison results between the Hasse-Witt invariants w_t(E) of a symmetric bundle E ... more We establish comparison results between the Hasse-Witt invariants w_t(E) of a symmetric bundle E over a scheme and the invariants of one of its twists E_{\alpha}. For general twists we describe the difference between w_t(E) and w_t(E_{\alpha}) up to terms of degree 3. Next we consider a special kind of twist, which has been studied by A. Fr\"ohlich. This arises from twisting by a cocycle obtained from an orthogonal representation. We show how to explicitly describe the twist for representations arising from very general tame actions. This involves the ``square root of the inverse different'' which Serre, Esnault, Kahn, Viehweg and ourselves had studied before. For torsors we show that, in our geometric set-up, Jardine's generalization of Frohlich's formula holds. The case of genuinely tamely ramified actions is geometrically more involved and leads us to introduce a ramification invariant which generalises in higher dimension the invariant introduced by Serre for curves.

Research paper thumbnail of Hermitian modules in galois extensions of number elds and Adams operations

Research paper thumbnail of Equivariant Euler-Poincar'e characteristics and tameness

Research paper thumbnail of The Galois structure of the trace form in extensions of odd prime degree

Research paper thumbnail of The Galois structure of the square root of the inverse different

Mathematische Zeitschrift, 1991

Research paper thumbnail of On the E-constants of a variety over a finite field

American Journal of Mathematics, 1997

Research paper thumbnail of Epsilon constants and the Galois structure of de Rham cohomology

Research paper thumbnail of Invitation to higher local fields, Part II, section 10: Galois modules and class field theory

This is a concise survey of links between Galois module theory and class field theory (CFT). It e... more This is a concise survey of links between Galois module theory and class field theory (CFT). It explores various uses of CFT in Galois module theory, it comments on the absence of CFT in contexts where it might be expected to play a role and indicates some lines of research that might bring CFT to play a more prominent role in Galois module theory.

Research paper thumbnail of 10. Galois modules and class field theory

Research paper thumbnail of Forme Trace et Ramification Sauvage

Proceedings of The London Mathematical Society, 1990

Research paper thumbnail of The hermitian structure of rings of integers in odd degree abelian extensions

Journal of Number Theory, 1992

Research paper thumbnail of Riemann-Roch type theorems for schemes with a finite group action

Research paper thumbnail of Tame actions of group schemes: integrals and slices

Duke Mathematical Journal, 1996

Research paper thumbnail of Riemann-Roch type theorems for arithmetic schemes with a finite group action

Journal Fur Die Reine Und Angewandte Mathematik, 1997

Research paper thumbnail of Twists of symmetric bundles

We establish comparison results between the Hasse-Witt invariants w_t(E) of a symmetric bundle E ... more We establish comparison results between the Hasse-Witt invariants w_t(E) of a symmetric bundle E over a scheme and the invariants of one of its twists E_{\alpha}. For general twists we describe the difference between w_t(E) and w_t(E_{\alpha}) up to terms of degree 3. Next we consider a special kind of twist, which has been studied by A. Fr\"ohlich. This arises from twisting by a cocycle obtained from an orthogonal representation. We show how to explicitly describe the twist for representations arising from very general tame actions. This involves the ``square root of the inverse different'' which Serre, Esnault, Kahn, Viehweg and ourselves had studied before. For torsors we show that, in our geometric set-up, Jardine's generalization of Frohlich's formula holds. The case of genuinely tamely ramified actions is geometrically more involved and leads us to introduce a ramification invariant which generalises in higher dimension the invariant introduced by Serre for curves.

Research paper thumbnail of On the <img src="/fulltext-image.asp?format=htmlnonpaginated&src=PP0U0M22EE306ABU_html\" border="0" alt="$\epsilon$" />-constants of arithmetic schemes

Mathematische Annalen, 1998

Research paper thumbnail of Hasse–Witt invariants of symmetric complexes: an example from geometry

Comptes Rendus Mathematique, 2002

ABSTRACT Jardine has defined Hasse–Witt invariants for symmetric bundles over schemes. This defin... more ABSTRACT Jardine has defined Hasse–Witt invariants for symmetric bundles over schemes. This definition can be extended to symmetric complexes, that is symmetric objects in the derived category of bounded complexes of vector bundles over a scheme. In this Note we show how one can use these generalized invariants to give a neater proof of a comparison result on Hasse–Witt invariants of symmetric bundles attached to tame coverings of schemes. To cite this article: P. Cassou-Noguès et al., C. R. Acad. Sci. Paris, Ser. I 334 (2002) 839–842.

Research paper thumbnail of Twists of symmetric bundles

Proceedings of The London Mathematical Society, 2007

We establish comparison results between the Hasse-Witt invariants w_t(E) of a symmetric bundle E ... more We establish comparison results between the Hasse-Witt invariants w_t(E) of a symmetric bundle E over a scheme and the invariants of one of its twists E_{\alpha}. For general twists we describe the difference between w_t(E) and w_t(E_{\alpha}) up to terms of degree 3. Next we consider a special kind of twist, which has been studied by A. Fr\"ohlich. This arises from twisting by a cocycle obtained from an orthogonal representation. We show how to explicitly describe the twist for representations arising from very general tame actions. This involves the ``square root of the inverse different'' which Serre, Esnault, Kahn, Viehweg and ourselves had studied before. For torsors we show that, in our geometric set-up, Jardine's generalization of Frohlich's formula holds. The case of genuinely tamely ramified actions is geometrically more involved and leads us to introduce a ramification invariant which generalises in higher dimension the invariant introduced by Serre for curves.

Research paper thumbnail of Hermitian modules in galois extensions of number elds and Adams operations

Research paper thumbnail of Equivariant Euler-Poincar'e characteristics and tameness

Research paper thumbnail of The Galois structure of the trace form in extensions of odd prime degree

Research paper thumbnail of The Galois structure of the square root of the inverse different

Mathematische Zeitschrift, 1991

Research paper thumbnail of On the E-constants of a variety over a finite field

American Journal of Mathematics, 1997

Research paper thumbnail of Epsilon constants and the Galois structure of de Rham cohomology

Research paper thumbnail of Invitation to higher local fields, Part II, section 10: Galois modules and class field theory

This is a concise survey of links between Galois module theory and class field theory (CFT). It e... more This is a concise survey of links between Galois module theory and class field theory (CFT). It explores various uses of CFT in Galois module theory, it comments on the absence of CFT in contexts where it might be expected to play a role and indicates some lines of research that might bring CFT to play a more prominent role in Galois module theory.

Research paper thumbnail of 10. Galois modules and class field theory

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