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algebraic categories and representations of classes of algebras (Topic)

Introduction

Classes of algebras can be categorized at least in two types: either classes of specific algebras, such as: group algebras, K-algebras, groupoid algebras, logic algebras, and so on, or general ones, such as general classes of: categorical algebras, higher dimensional algebra (HDA), supercategorical algebras, universal algebras, and so on.

Basic concepts and definitions

  • Class of algebras
    Definition 0.1   A class of algebras is defined in a precise sense as an algebraic object in the groupoid category.
  • Monad on a category $\mathcal{C}$, and a T-algebra in $\mathcal{C}$
    Definition 0.2   Let us consider a category $\mathcal{C}$, two functors: $T: \mathcal{C} \to \mathcal{C}$ (called the monad functor) and $T^2: \mathcal{C} \to \mathcal{C} = T \circ T$, and two natural transformations: $\eta: 1_ \mathcal{C} \to T$ and $\mu: T^2 \to T$. The triplet $(\mathcal{C},\eta,\mu)$ is called a monad on the category $\mathcal{C}$. Then, a T-algebra $(Y,h)$ is defined as an object $Y$ of a category $\mathcal{C}$ together with an arrow $h: TY \to Y $ called the structure map in $\mathcal{C}$ such that:

    1. $\displaystyle Th: T^2 \to TY,$

    2. $\displaystyle h \circ Th = h \circ \mu_Y,$
      where: $\mu_Y: T^2 Y \to TY;$ and

    3. $\displaystyle h \circ \eta_Y = 1_Y.$
  • Category of Eilenberg-Moore algebras of a monad $T$

    An important definition related to abstract classes of algebras and universal algebras is that of the category of Eilenberg-Moore algebras of a monad $T$:

    Definition 0.3   The category $\mathcal{C}^T$ of $T$-algebras and their morphisms is called the Eilenberg-Moore category or category of Eilenberg-Moore algebras of the monad T.

Pertinent remarks:

  • a. Algebraic category definition
    Remark 0.1   With the above definition, one can also define a category of classes of algebras and their associated groupoid homomorphisms which is then an algebraic category.

    Another example of algebraic category is that of the category of C*-algebras.

    Generally, a category $\mathcal{A}_C$ is called algebraic if it is monadic over the category of sets and set-theoretical mappings, $Set$; thus, a functor $G: \mathcal{D} to \mathcal{C}$ is called monadic if it has a left adjoint $F: \mathcal{C}\to \mathcal{D}$ forming a monadic adjunction $(F,G,\eta,\epsilon)$ with $G$ and $\eta, \epsilon$ being, respectively, the unit and counit; such a monadic adjunction between categories $\mathcal{C}$ and $\mathcal{D}$ is defined by the condition that category $\mathcal{D}$ is equivalent to the to the Eilenberg-Moore category $\mathcal{C} ^T$ for the monad

    $\displaystyle T = GF.$
  • b. Equivalence classes
    Remark 0.2   Although all classes can be regarded as equivalence, weak equivalence, etc., classes of algebras (either specific or general ones), do not define identical, or even isomorphic structures, as the notion of `equivalence' can have more than one meaning even in the algebraic case.

Algebraic representations

  • group representations
  • groupoid representations
  • Convolution C*-algebra groupoid representations
  • Functorial representations and representable functors
  • Categorical group representations
  • Algebroid representations
  • Quantum Algebroid (QA) representations
  • Double groupoid representations
  • Double Algebroid representations
  • Grassman-Hopf representations



"algebraic categories and representations of classes of algebras" is owned by bci1.

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See Also: complex categorical dynamics

Also defines:  functorial representations, categorical group representation, monad, monad functor, algebraic category, representations, T-algebra, algebraic and group representations, class of algebra, Eilenberg-Moore category of algebras, convolution C*-algebra groupoid representations, algebroid representations, double groupoid representations, double algebroid representations, quantum algebroid
Keywords:  representations of classes of algebras, monad, monad functor, algebraic category, representations, T-algebra, algebraic and group representations, class of algebra, Eilenberg-Moore category of algebras, convolution C*-algebra groupoid representations, algebroid representations, double groupoid representations, double algebroid representations, quantum algebroid, monads, adjoint pairs, monadic functors, Eilenberg-Moore category of algebras, adjointness and natural transformations, category equivalence

Cross-references: representable functors, groupoid representations, group representations, monadic, category of C*-algebras, groupoid homomorphisms, morphisms, natural transformations, functors, category, groupoid category, object, algebraic, HDA, higher dimensional algebra, categorical algebras, groupoid, group, types
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This is version 7 of algebraic categories and representations of classes of algebras, born on 2009-01-24, modified 2009-04-17.
Object id is 422, canonical name is AlgebraicCategoriesAndRepresentationsOfClassesOfAlgebras.
Accessed 3879 times total.

Classification:
Physics Classification: 02. (Mathematical methods in physics)
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