Lemmas in linear algebra | Matrix theory | K-theory | Theorems in abstract algebra

Whitehead's lemma

Whitehead's lemma is a technical result in abstract algebra used in algebraic K-theory. It states that a matrix of the form is equivalent to the identity matrix by elementary transformations (that is, transvections): Here, indicates a matrix whose diagonal block is and entry is . The name "Whitehead's lemma" also refers to the closely related result that the derived group of the stable general linear group is the group generated by elementary matrices. In symbols, . This holds for the stable group (the direct limit of matrices of finite size) over any ring, but not in general for the unstable groups, even over a field. For instance for one has: where Alt(3) and Sym(3) denote the alternating resp. symmetric group on 3 letters. (Wikipedia).

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Proof of Lemma and Lagrange's Theorem

Please Subscribe here, thank you!!! https://goo.gl/JQ8Nys Proof of Lemma and Lagrange's Theorem. This video starts by proving that any two right cosets have the same cardinality. Then we prove Lagrange's Theorem which says that if H is a subgroup of a finite group G then the order of H div

From playlist Abstract Algebra

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Burnside's Lemma (Part 1) - combining group theory and combinatorics

A result often used in math competitions, Burnside's lemma is an interesting result in group theory that helps us count things with symmetries considered, e.g. in some situations, we don't want to count things that can be transformed into one another by rotation different, like in this cas

From playlist Traditional topics, explained in a new way

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From playlist Theory of numbers

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Measure Theory 3.1 : Lebesgue Integral

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From playlist Measure Theory

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From playlist Traditional topics, explained in a new way

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The Schwarz Lemma -- Complex Analysis

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From playlist Complex Analysis

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From playlist Geometry, Groups and Dynamics (GGD) - 2017

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From playlist Algebra

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Mohammed Abouzaid: Nearby Lagrangians are simply homotopic

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From playlist Jean-Morlet Chair - Lalonde/Teleman

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From playlist 2019 - T2 - Reinventing rational points

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Riemann-Lebesgue Lemma

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From playlist Real Analysis

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From playlist Introduction to Homotopy Theory

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From playlist Categories for the idle mathematician

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From playlist Topological Complexity Seminar

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Mark Feighn: The conjugacy problem for polynomially growing elements of Out(F_n)

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From playlist Topology

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Giles Gardam: Kaplansky's conjectures

Talk by Giles Gardam in the Global Noncommutative Geometry Seminar (Americas) https://globalncgseminar.org/talks/3580/ on September 17, 2021.

From playlist Global Noncommutative Geometry Seminar (Americas)

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ITHT: Part 9- The Homotopy Category

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From playlist Introduction to Homotopy Theory

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Lecture 11: Negative Topological cyclic homology

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From playlist Topological Cyclic Homology

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RIngs 22 Hensel's lemma

This lecture is part of an online course on rings and modules. We continue the previous lecture on complete rings by discussing Hensel's lemma for finding roots of polynomials over p-adic rings or over power series rings. We sketch two proofs, by slowly improving a root one digit at a tim

From playlist Rings and modules

Related pages

Identity matrix | Special linear group | Abstract algebra | Symmetric group | Algebraic K-theory | Alternating group | Matrix (mathematics) | Direct limit