Re: an odd ambiguity

d(n) = |{ d | d||n| }|

In the system I am developing (which allows the author to
specify the intent, and then output MathML which follows
the standards we are developing), this can be entered in any
of the following equivalent ways:

d(n) = card({ d | d|abs(n) })

d(n) = card { d | d|abs n }

d(n) = card { d : d|abs(n) }

The expression |A| , which could mean absolute value, cardinality,
order, length, ..., should not be entered literally.  Instead,
write it as abs(A), card(A), etc.  The parentheses are optional.
(If in a document |A| always means the same thing, then it will
be possible to type |A| and interpret it with the specified

In set builder notation, the separator can be entered as "|" or
":" .  The output can be chosen to be either of those symbols,
depending on the choice of the publisher (default is what the
author wrote).

The spaces in the above examples are part of the syntax.  The second
line in (what I hope is) a correctly pronouncing form:

d left paren n right paren space equals space c a r d space
left curly bracket space d space pipe space d pipe a b s space
n space right curly bracket

I'd be interested in hearing how others will have authors
specify the intent.

Received on Thursday, 5 August 2021 12:06:10 UTC