# Best practice for typesetting Knuth's up-Arrow notation

What's the best practice to typeset Knuth's up-Arrow notation?

`\uparrow` and `\upuparrow` are relation symbols (according to `unimath-symbols.pdf`). But in Knuth's up arrow notation, these should be a binary operator. So, how should on treat this difference?

Secondly, should double up arrows be typeset as `\upuparrow` or as `\uparrow\uparrow`, which illustrates the double nature better.

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For the first part, you could define a command using `\mathbin`,as in `\newcommand\kuparrow{\mathbin{\uparrow}}`. – Gonzalo Medina Apr 22 '13 at 19:20

There is a command `\mathbin` for creation of binary operators, so something like
``````\newcommand\binuparrow{\mathbin{\uparrow}}