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For $n$-dimensional real number set $\mathbb{R}^n$, its $n-1$ dimensional subspaces are called hyperplanes. Are there special names for lower dimensional subspace of $\mathbb{R}^n$?

  • "Subspace of dimension $k$" (where $k \leq n$) is quite specific. – avs Feb 02 '17 at 17:42
  • I have heard the term "hyperplane" refer to any $m$-dimensional subspace of $\mathbb R^n$ for $m<n$. I'd go with avs's suggestion though. – Wojowu Feb 02 '17 at 17:44
  • I seem to recall $k$-flats referring to $k$-dimensional (affine) subspaces, but evidently it's less common than I'd thought. – pjs36 Feb 02 '17 at 17:44
  • @Wojowu I used to think that way, too. But I recently read that hyperplane was only for n-1 subspace. Thus the question. – Guangliang Feb 02 '17 at 18:46

2 Answers2

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An $n-k$ dimensional linear subspace of $\mathbb{R}^n$ is often called a codimension $k$ subspace. I don't believe a more general term exists.

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I bet you already know that :

  • A subspace of dimension $1$ is called a line.

  • A subspace of dimension $2$ is called a plane.

  • A subspace of codimension $1$ is called an hyperplane (as you stated).

C. Falcon
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