# Re: a content question/suggestion

From: David Carlisle <davidc@nag.co.uk>
Date: Mon, 18 Dec 2000 17:43:29 GMT
Message-Id: <200012181743.RAA32603@penguin.nag.co.uk>



> I noticed that you took up my suggestion andnow allow the qualifiers to
> appear with any "head" operator. Good!

yes, sounds like we didn't explicitly reply to you saying we'd do that,
sorry.

> (sorry for using OpenMath terminology here)
I can probably cope:-)

>  - bvar introduces a bound variable
this is certainly the intent. Where "bound variable" has to be
interpreted with some care

x is expressed using a bvar in \int x dx even though x is free
there. This could be rationalised by saying that \int x dx is syntactic
shorthand for
( \int  (\lambda x. x) dx) (x)
(which is how it would be encoded in OpenMath) and the inner use of x is
bound.

>  - that variable's scope is the surrounding apply
This is also the intent.

- except for <interval> qualifiers as immediate children of the
surrounding apply

4.2.3.2 (Operators taking qualifiers)
says:
> Qualifiers always follow the operator and precede the argument if it is
> present. If more than one qualifier is present, they appear in the order
> bvar, lowlimit, uplimit, interval, condition, domainofapplication,
> degree, momentabout, logbase. A typical example is:

which does constrain qualifiers to being immediate children of the apply
doesn't it?

The description of bvar in 4.4.5.6 does say

> Discussion
> The bvar element is the container element for the bound variable' of an
> operation

so I think it is clear that use of bvar with other newly introduced
constructs should not change that. It does go on to say

> The meaning of the bvar element depends on the context it is being used
> in. For further details about how qualifiers are used in conjunction
> with operators taking qualifiers, consult Section 4.2.3.2 [Operators
> taking Qualifiers].

I'm not sure if that can really be made any more constrained given
existing differences in the use of bvar between the various elements.

Do you have any explicit example in mind that you think would be a) bad
and b) allowed by the current spec. (It's getting too close to Christmas
to consider problems in the abstract, need concrete examples:-)

David

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Received on Monday, 18 December 2000 12:43:37 UTC

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