RegistryQuery query

[Arnold Rots]

Unless you read NOT_EQUAL as a combination of a binary operator
(EQUAL) and a unary operator (NOT):
i.e., read "A NOT_EQUAL B" as "A EQUAL (NOT B)"

  - Arnold

Tony Linde wrote:
> Isn't it usual that NOT is a unary operator which reverses the boolean value
> of an operand and NOT_EQUAL (<> or !=) is a binary operator with the usual
> meaning(s).
> 
> Cheers,
> Tony. 
> 
> > -----Original Message-----
> > From: owner-registry at eso.org [mailto:owner-registry at eso.org] 
> > On Behalf Of Matthew Graham
> > Sent: 08 June 2004 21:55
> > To: Tony Linde
> > Cc: registry at ivoa.net
> > Subject: RegistryQuery query
> > 
> > 
> > Hi,
> > 
> > I have been looking at the QueryResource schema and was 
> > wondering about the "not" operand - is it supposed to be an 
> > existence operator or test whether a particular ResourceXPath 
> > is true or false? In either case the proposed syntax strikes 
> > me as being rather like Reverse Polish:
> > 
> > <ResourceXPath> not 
> > 
> > or
> > 
> > <ResourceXPath> not <value = true/false?>
> > 
> > Is it actually supposed to be the <does-not-equal> operator, 
> > in which case can it be renamed to that?
> > 
> > 	Cheers,
> > 
> > 	Matthew
> > 
> 
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Arnold H. Rots                                Chandra X-ray Science Center
Smithsonian Astrophysical Observatory                tel:  +1 617 496 7701
60 Garden Street, MS 67                              fax:  +1 617 495 7356
Cambridge, MA 02138                             arots at head.cfa.harvard.edu
USA                                     http://hea-www.harvard.edu/~arots/
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