Re: [xsl] Where is 'intersect' Operator Defined in XPath 3?

["C. M. Sperberg-McQueen cmsmcq@xxxxxxxxxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

"Michael Kay mike@xxxxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> writes:

> On the other hand, we pretty well treat it as obvious that 2 + 2 is 4. 

True, at least in part.  I don't believe the specs attempt to define the
laws of arithmetic or other parts of mathematics.

But F&O section 4.2.1[1] does say explicitly:

    4.2.1 op:numeric-add

    Summary

    Returns the arithmetic sum of its operands: ($arg1 + $arg2).

and there is discussion of how zero and INF interact, as well as a
pointer to a general discussion of overflow and related issues.

I do agree that at some point one has to assume some common ground with
the reader.  If we assume too little common ground, the spec is
unnecessarily explicit, which irritates some readers.  If we assume too
much, interoperability is likely to suffer.

More precision may be combinable with brevity if formalisms like Z or
Alloy (or like the formalism in the QT Formal Semantics spec) are used
-- but that seems unlikely to help much in practice, seeing how
frequently even simpler better established formalisms like BNF seem to
overtax the patience of some WG participants.


-- 
C. M. Sperberg-McQueen
Black Mesa Technologies LLC
http://blackmesatech.com