÷ vs :

On the call today, we discussed issue 473
<https://github.com/w3c/mathml/issues/473> which is about what intent
values should be used with differentiation. In it, Deyan brings up division
which led to a discussion of ÷ and : for division -- something that led to
some surprising differences amongst attendees. After the meeting, Deyan
mentioned Cajori's book on the history of math notations and how ÷ actually
was originally an alternative to "-" for minus.

I read a bit more and on p272, Cajori writes "There are perhaps no symbols
which are as completely observant of political boundaries as are ÷ and : as
symbols for division. The former belongs to Great Britain, the British
dominions, and the United States. The latter belongs to Continental Europe
and the Latin-American countries... Such statements would not apply to the
symbolisms for the differential and integral calculus, not even for the
eighteenth century."

I thought perhaps the decimal separator was another instance, so I looked
to see what Cajori wrote. His book was published in 1929. He said that in
the US, "." came to become the standard after about 1850. Something I never
knew is that the centered dot was used by many to mean both multiplication
and decimal separator because that meant the decimal separator wouldn't be
confused with a punctuation ".". Apparently, that was the case in Great
Britain in 1929. And of course, ","  was used in other countries. I'm glad
to see that the Brits came to their senses since then :-)

As always, Cajori is an interesting read for those who want to know
something about the history of math notation. It is also a reminder that
math notation is an evolving topic. It gives a little comfort to me that if
we don't get the naming of intents right, we will be in good company for
not getting it right the first time.

    Neil