Use of 1/2 in a field is confusing

[eriktaubeneck]

It would probably be clearer to use $2^{-1}$, and maybe even define it, e.g., "... subtracting the multiplicative inverse of 2, $2^{-1}$, ..."

[martinthomson]

Yeah, we have a note at some point in the document saying what 1/2 actually is. I thought that was fine, but Ben and I didn't really settle on anything.

It might be worth adding to that note.