nLab
Vect
Context
Category theory
category theory

Concepts
Universal constructions
Theorems
Extensions
Applications
Linear algebra
homotopy theory

Introductions
Background
Variations
Definitions
Paths and cylinders
Homotopy groups
Theorems
Contents
Definition
Given a field $k$ , the category of $k$ -vector spaces $Vect_k$ is the category whose

objects are vector space ,

morphisms are linear maps .

If the field $k$ is understood, one often just writes $Vect$ .

Via direct sum and tensor product of vector spaces $\otimes_k$ , this becomes a symmetric monoidal category in two compatible ways, making it a distributive monoidal category , in particular a rig category .

The study of $Vect$ is called linear algebra .

Finite-dimensional vector spaces
The full subcategory of Vect consisting of finite-dimensional vector spaces is denoted $\Fin Vect$ .

This is a compact closed category (see here ).

$\Fin Vect$ is where most of ordinary linear algebra lives, although much of it makes sense in all of $Vect$ . See also at finite quantum mechanics in terms of dagger-compact categories .

On the other hand, anything involving transposes or inner products really takes place in $Fin$ Hilb .

Modules
More generally, for $R$ any ring (not necessarily a field ) then the analog of $Vect$ is the category $R$ Mod of $R$ -modules and module homomorphisms between them.

Vector bundles
For $X$ a suitable space of sorts, there is the category Vect(X) of vector bundles over $X$ . Specifically for $X$ a topological space , there is the category of topological vector bundles over $X$ . For $X = \ast$ the point space , then this is equivalently the category of plain vector spaces:

$Vect(\ast) \simeq Vect
\,.$

Revised on May 26, 2017 01:46:15
by

Urs Schreiber
(92.218.150.85)