multi-symbol variables

Taking this discussion out of GitHub.  I hope this is the right

The important point which has arisen, which I believe we had not
discussed previously, is how to mark a multi-letter string as
representing a single variable.  For example, on this page:

it says

Interest = p \times r \times t .

Here "Interest" is an 8 character string which represents one

This is analogous to the situation in our recent discussions,
where B' is just one quantity which happens to be a string of
two characters.  The fact that one of the characters is a prime
is not the main issue.  I mentioned an example where a_1 was a
(subscripted) string which also is really just a single variable.

Prior to this week I don't think we had discussed the fact that
B' is a 2-character quantity, while f' -- assuming that means the
derivative of f -- is the object f on which ' is acting.

The only point I am trying to make here is that we need a way to
indicate that a collection of characters is really in indivisible
unit which represents a single quantity.  The recent discussions were
made more difficult by the fact that this had not been discussed

I suggest that " B' " should be handled the same way as " Interest "
would be handled in the formula above.


David Farmer

Received on Friday, 8 October 2021 03:09:41 UTC