Finite groups | Subgroup properties
In mathematical group theory, a subgroup of a group is termed a special abelian subgroup or SA-subgroup if the centralizer of any nonidentity element in the subgroup is precisely the subgroup. Equivalently, an SA subgroup is a centrally closed abelian subgroup. * Any SA subgroup is a maximal abelian subgroup, that is, it is not properly contained in another abelian subgroup. * For a CA group, the SA subgroups are precisely the maximal abelian subgroups. SA subgroups are known for certain characters associated with them termed exceptional characters. (Wikipedia).
Jacob explains the fundamental concepts in group theory of what groups and subgroups are, and highlights a few examples of groups you may already know. Abelian groups are named in honor of Niels Henrik Abel (https://en.wikipedia.org/wiki/Niels_Henrik_Abel), who pioneered the subject of
From playlist Basics: Group Theory
Before we carry on with our coset journey, we need to discover when the left- and right cosets are equal to each other. The obvious situation is when our group is Abelian. The other situation is when the subgroup is a normal subgroup. In this video I show you what a normal subgroup is a
From playlist Abstract algebra
Every Subgroup of an Abelian Group is Normal Proof
Please Subscribe here, thank you!!! https://goo.gl/JQ8Nys Every Subgroup of an Abelian Group is Normal Proof
From playlist Abstract Algebra
This lecture is part of an online math course on group theory. We review free abelian groups, then construct free (non-abelian) groups, and show that they are given by the set of reduced words, and as a bonus find that they are residually finite.
From playlist Group theory
In this tutorial we define a subgroup and prove two theorem that help us identify a subgroup. These proofs are simple to understand. There are also two examples of subgroups.
From playlist Abstract algebra
Abstract Algebra | Normal Subgroups
We give the definition of a normal subgroup and give some examples. http://www.michael-penn.net http://www.randolphcollege.edu/mathematics/
From playlist Abstract Algebra
Every Group of Order Five or Smaller is Abelian Proof
Please Subscribe here, thank you!!! https://goo.gl/JQ8Nys Every Group of Order Five or Smaller is Abelian Proof. In this video we prove that if G is a group whose order is five or smaller, then G must be abelian.
From playlist Abstract Algebra
Karen Vogtmann - On the cohomological dimension of automorphism groups of RAAGs
The class of right-angled Artin groups (RAAGs) includes free groups and free abelian groups, Both of these have extremely interesting automorphism groups, which share some properties and not others. We are interested in automorphism groups of general RAAGs, and in particular
From playlist Groupes, géométrie et analyse : conférence en l'honneur des 60 ans d'Alain Valette
This project was created with Explain Everything™ Interactive Whiteboard for iPad.
From playlist Modern Algebra
Please Subscribe here, thank you!!! https://goo.gl/JQ8Nys The Klein Four-Group is the smallest noncyclic abelian group. Every proper subgroup is cyclic. We look at the the multiplication in the Klein Four-Group and find all of it's subgroups.
From playlist Abstract Algebra
Justin Lynd: Control of fixed points and centric linking systems
The lecture was held within the framework of the (Junior) Hausdorff Trimester Program Topology: Workshop "Fusion systems and equivariant algebraic topology"
From playlist HIM Lectures: Junior Trimester Program "Topology"
GT6. Centralizers, Normalizers, and Direct Products
Abstract Algebra: We consider further methods of constructing new groups from old. We consider centralizer and normalizer subgroups, which are useful when the group is non-abelian, and direct products. U.Reddit course materials available at http://ureddit.com/class/23794/intro-to-group-t
From playlist Abstract Algebra
EDIT: At 11:50, r^2(l-k) should be r^2l. At 14:05, index for top one should be n-2, not 2n-2. Abstract Algebra: We define the commutator subgroup for a group G and the corresponding quotient group, the abelianization of G. The main example is the dihedral group, which splits into tw
From playlist Abstract Algebra
RT3. Equivalence and Examples (Expanded)
Representation Theory: We define equivalence of representations and give examples of irreducible representations for groups of low order. Then we use the commutator subgroup to characterize all one dimensional representations of G (characters) in terms of the abelianization of G. Course
From playlist Representation Theory
Group theory 17: Finite abelian groups
This lecture is part of a mathematics course on group theory. It shows that every finitely generated abelian group is a sum of cyclic groups. Correction: At 9:22 the generators should be g, h+ng not g, g+nh
From playlist Group theory
Wouter Castryck, An efficient key recovery attack on supersingular isogeny Diffie-Hellman
VaNTAGe Seminar, October 18, 2022 License: CC-BY-NC-SA Links to some of the papers mentioned in this talk: Rostovstev-Stolbunov: https://eprint.iacr.org/2006/145 Charles-Goren-Lauter: https://eprint.iacr.org/2006/021 Jao-De Feo: https://eprint.iacr.org/2011/506 Castryck-Decru: https://e
From playlist New developments in isogeny-based cryptography
Ben Howard: Supersingular points on som orthogonal and unitary Shimura varieties
To an orthogonal group of signature (n,2), or to a unitary group of any signature, one can attach a Shimura variety. The general problem is to describe the integral models of these Shimura varieties, and their reductions modulo various primes. I will give a conjectural description of the s
From playlist HIM Lectures: Junior Trimester Program "Algebraic Geometry"
Cyril Demarche: Cohomological obstructions to local-global principles - lecture 3
Hasse proved that for quadrics the existence of rational points reduces to the existence of solutions over local fields. In many cases, cohomological constructions provide obstructions to such a local to global principle. The objective of these lectures is to give an introduction to these
From playlist Algebraic and Complex Geometry
We give a buttload of definitions for morphisms on various categories of complexes. The derived category of an abelian category is a category whose objects are cochain complexes and whose morphisms I describe in this video.
From playlist Derived Categories
Group theory 25: The transfer homomorphism
This video is part of an online mathematics course on group theory. It describes the transfer homomorphism between groups, and uses it to classify groups of order 30 and to show that the order of any simple group must be divisible by the square of some prime.
From playlist Group theory