Splitting Fields
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✓ 16 results · all verified · 11 also independently AI-judged
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1 · Prerequisites
Abstract Algebra
- Binary Operations, Monoids, Groups and Subgroups
- Cosets, Index and Lagrange's Theorem
- Divisibility, Euclidean Domains, Principal Ideal Domains and Unique Factorisation
- Group Homomorphisms and the Isomorphism Theorems
- Ideals, Quotient Rings and the Isomorphism Theorems for Rings
- Normal Subgroups and Quotient Groups
- Polynomial Rings, the Division Algorithm and Roots
- Rings, Subrings, Integral Domains and Fields
- Simple Field Extensions and the Construction of the Complex Numbers
Real Analysis
2 · Logical flowchart
3 · Items
Definition
Polynomials that split and splitting fields of a polynomial or a family of polynomials
Lemma
Kronecker's one-root step: adjoining a root removes a linear factor and lowers the remaining degree
Theorem
Every nonzero polynomial over a field has a splitting field
Corollary
Every finite family of nonzero polynomials has a splitting field, obtained from their product
Corollary
Inside a common extension, the splitting field of fg is the composite of the splitting fields of f and g
Lemma
A field isomorphism transports polynomials coefficientwise and carries roots, factorizations, and splitting to roots, factorizations, and splitting
Lemma
A base-field isomorphism extends across simple adjunctions of corresponding roots of an irreducible polynomial
Theorem
A base-field isomorphism extends to an isomorphism between splitting fields of corresponding polynomials
Corollary
Any two splitting fields of a polynomial are isomorphic over the base field
Theorem
A degree-n polynomial has a splitting field spanned over F by at most n! explicit root monomials
Proposition
After adjoining one nonzero root α of xⁿ-a, all roots are ζα with ζⁿ=1
Proposition
Every F-endomorphism of a splitting field permutes the distinct roots and is an automorphism
Definition
A normal algebraic extension is one in which every minimal polynomial with a root in the extension splits there
Proposition
If K/F is normal and F⊆ E⊆ K, then K/E is normal
Proposition
A nonempty intersection of normal subextensions inside a common algebraic extension is normal
Proposition
An algebraic extension that is a splitting field of a polynomial is normal
Theorem
An algebraic extension generated by elements whose minimal polynomials split in it is normal
Proposition
A normal extension generated by finitely many elements is the splitting field of the product of their minimal polynomials
Sources
- T. Judson, Abstract Algebra: Theory and Applications, Section 21.2
- J. S. Milne, Fields and Galois Theory, Chapter 2
- T. Judson, Abstract Algebra: Theory and Applications, Theorem 21.11
- T. Judson, Abstract Algebra: Theory and Applications, Theorem 21.13
- J. S. Milne, Fields and Galois Theory, Proposition 2.11
- T. Judson, Abstract Algebra: Theory and Applications, Corollary 21.14
- T. Judson, Abstract Algebra: Theory and Applications, Theorem 21.12
- The Stacks Project, Section 9.15: Normal extensions
- The Stacks Project, Lemma 9.15.6
- The Stacks Project, Lemma 9.15.8
- The Stacks Project, Lemma 9.15.9
- J. S. Milne, Fields and Galois Theory, Proposition 2.12
- The Stacks Project, Lemma 9.15.11