Definition:Dimension of Vector Space

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Definition

Let $K$ be a division ring.

Let $V$ be a vector space over $K$.


Definition 1

The dimension of $V$ is the number of vectors in a basis for $V$.


Definition 2

The dimension of $V$ is the maximum cardinality of a linearly independent subset of $V$.


Finite Dimensional Vector Space

Let $V$ be a vector space which is $n$-dimensional for some $n \in \N_{>0}$.

Then $V$ is finite dimensional.


The dimension of a finite-dimensional $K$-vector space $V$ is denoted $\map {\dim_K} V$, or just $\map \dim V$.


Dimension of Vector

Informally, an element of an $n$-dimensional vector space is often referred to as an $n$-dimensional vector.

It must be understood that this is no more than a convenient shorthand. It is not the vector which possesses the dimensionality, but the space in which it is embedded.


Also see