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  "body": "\n## Summary\n\nA BK-space is a [[sequence space|XYTN19EPF2]] with a norm that makes it a [[Banach space|06GZ956657]] in which each coordinate $x \\mapsto x_n$ is continuous.\nThe letters stand for Banach and the German word Koordinate.\nBK-spaces are exactly the [[FK-spaces|71DMQHW6JZ]] whose topology comes from a norm.\nThe spaces $\\ell^p$, $c$ and $c_0$ with their usual norms are the basic examples.\n\n## Explanations\n\n### L1 human\n\nA BK-space is a space of sequences with a way of measuring size, a norm, that behaves well.\nThe space is complete, so there are no \"missing\" limits.\nAnd a small norm forces every single term of the sequence to be small.\nFor example, in the space of bounded sequences the norm is the largest absolute value of the terms, so each term is at most the norm.\n",
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