Cyclic Extensions, Kummer Extensions and Solvability by Radicals
Cyclic Extensions, Kummer Extensions and Solvability by Radicals: core definitions, structural results and verification methods in abstract algebra.
Every page in the KEVOS library tagged extensions. 17 pages.
Cyclic Extensions, Kummer Extensions and Solvability by Radicals: core definitions, structural results and verification methods in abstract algebra.
Handbook guide to cyclotomic fields and cubic galois groups with core definitions, structural results, reasoning methods and verification checks.
Handbook guide to field extensions and automorphism correspondence, covering definitions, key results, methods, verification checks and worked examples.
Field Extensions, Minimal Polynomials and Extension Degree: core definitions, structural results and verification methods in abstract algebra.
A field is a set with addition and multiplication satisfying the familiar arithmetic laws, including additive inverses and multiplicative inverses for every nonzero element. Thi…
Handbook guide to integral extensions and quadratic extensions with core definitions, structural results, reasoning methods and verification checks.
Handbook guide to integral extensions, algebraic integers, with definitions, key results, methods, verification checks and worked examples.
Handbook guide to semidirect products, extensions, with definitions, key results, methods, verification checks and worked examples.
Handbook guide to separable and normal field extensions with core definitions, structural results, reasoning methods and verification checks.
Handbook guide to transcendental extensions and transcendence bases with core definitions, structural results, reasoning methods and verification checks.
Techniques for computing Ext: choice of variable, use of the long exact sequences, standard computations over the integers, and Ext for cyclic and finitely generated modules.
Extensions of modules, equivalence of extensions, the Baer sum defined by pullback and pushout, and the resulting abelian group structure on Ext.
Ext defined via extensions, via projective resolutions and via injective resolutions, the agreement of the three definitions, and the basic vanishing criteria.
The Stein-Serre theorem characterising countable torsion-free abelian groups that are free, via vanishing of Ext, and related Whitehead-type problems.
The tensor product by universal property and construction, right exactness, flat modules, and the tensor-hom adjunction.
Tor defined by projective resolutions, symmetry in its two variables, vanishing criteria, and the standard computations over the integers.
The long exact sequences of Ext in the first and second variables, their connecting homomorphisms, naturality, and the direction reversal caused by contravariance.