Galois Cohomology and Isomorphism Classification of Elliptic Curves over Arbitrary Fields

Author(s):  
René Zander

AbstractWe discuss the singularity structure of Kahan discretizations of a class of quadratic vector fields and provide a classification of the parameter values such that the corresponding Kahan map is integrable, in particular, admits an invariant pencil of elliptic curves.


2019 ◽  
Vol 377 (2) ◽  
pp. 1099-1129
Author(s):  
Eugene Karolinsky ◽  
Arturo Pianzola ◽  
Alexander Stolin

Author(s):  
D. Huybrechts

This chapter is devoted to results by Bondal and Orlov which show that for varieties with ample (anti-)canonical bundle, the bounded derived category of coherent sheaves determines the variety. Except for the case of elliptic curves, this settles completely the classification of derived categories of smooth curves. The complexity of the derived category is reflected by its group of autoequivalences. This is studied by means of ample sequences.


2021 ◽  
Vol 5 (1) ◽  
pp. 162-171
Author(s):  
Daniel C. Mayer ◽  

Each \(p\)-ring class field \(K_f\) modulo a \(p\)-admissible conductor \(f\) over a quadratic base field \(K\) with \(p\)-ring class rank \(\varrho_f\) mod \(f\) is classified according to Galois cohomology and differential principal factorization type of all members of its associated heterogeneous multiplet \(\mathbf{M}(K_f)=\lbrack(N_{c,i})_{1\le i\le m(c)}\rbrack_{c\mid f}\) of dihedral fields \(N_{c,i}\) with various conductors \(c\mid f\) having \(p\)-multiplicities \(m(c)\) over \(K\) such that \(\sum_{c\mid f}\,m(c)=\frac{p^{\varrho_f}-1}{p-1}\). The advanced viewpoint of classifying the entire collection \(\mathbf{M}(K_f)\), instead of its individual members separately, admits considerably deeper insight into the class field theoretic structure of ring class fields. The actual construction of the multiplet \(\mathbf{M}(K_f)\) is enabled by exploiting the routines for abelian extensions in the computational algebra system Magma.


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