This PR adds the inverse of a dyadic rational, at a given precision, and
characterising lemmas. Also cleans up various parts of the `Int.DivMod`
and `Rat` APIs, and proves some characterising lemmas about
`Rat.toDyadic`.
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Co-authored-by: Rob23oba <152706811+Rob23oba@users.noreply.github.com>
This PR defines the dyadic rationals, showing they are an ordered ring
embedding into the rationals. We will use this for future interval
arithmetic tactics.
Many thanks to @Rob23oba, who did most of the implementation work here.
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Co-authored-by: Rob23oba <robin.arnez@web.de>
