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DATETIME  May 2011

DATETIME May 2011

Subject:

Re: New approach about question marks - a suggestion

From:

"Edward C. Zimmermann" <[log in to unmask]>

Reply-To:

Discussion of the Developing Date/Time Standards <[log in to unmask]>

Date:

Tue, 10 May 2011 10:09:01 +0200

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (135 lines)

Its not terribly difficult to parse.
? is viewed as a postfix op. It applies to the term set before it.
x? means it applies to x where x is a expressive unit.
() are groups.
in (x)(y)(z)? the operator ? applies only to (z)
were x,y,z are expressive units.

In 2001?-12-06 the ? applies to 2001
In 2001-12-06? the ? applies to 06
In 2001-12?-06 the ? applies to 12
In 2001?-12?-06? the ? applies to the year. month and day.


In natural language this I think also makes sense. The expression
2001-12-06? means that one is less than certain on the day (06).

Metsärantala suggeted 
> > 2011-05-09? (* "?" applies to the whole date *)

But what does that mean?
The expression is a date readable to day and as such if one has a lower 
level of precision one would have used a different form. 

More concretely the expressions
2011-05-09?
2011-05-(09)?
2011-(05-09)?
(2011-05-09)?
are, I suggest, saying more or less the same thing.


2001-12? Says something like (puting some wild semantics in for ?)
 "I think it was in Dec 2001"
while 2001-12-06? says
 "I think it was the 6th of Dec 2001".
In this light I would argue that
2001-(12-06)? and 2001-12-06? are homologous.
The expression, by contrast, 2001?-12-06? says that
 "It was in Dec, I think perhaps the 6th and maybe 2001"


In our evolving model we have not just one postfix op but several and we 
don't limit them to single characters either.
Instead of viewing (x)~? as ((x)~)? its really the postfix op ~? whose 
semantics I would even suggest might not be the same as ((x)~)? or we may 
wish to demand a canonical form and demand its use--- one or the other.



On Mon, 9 May 2011 16:11:32 -0400, Bruce D'Arcus wrote
> Sorry if I haven't been paying close attention, but have we really
> established that all this complexity is valuable an necessary? Why not
> just (only) allow a trailing question mark that indicates whatever
> date is uncertain?
> 
> I get nervous about loading up this spec too much and banishing its
> use to a small corner of the library world.
> 
> On Mon, May 9, 2011 at 3:31 PM, [UTF-8?]SaaÅ¡ha Metsärantala 
<[log in to unmask]> wrote:
> > Hello!
> >
> > In this e-mail, I suggest a new approach about the question marks, which
> > could lead to an easier BNF and a more readable syntax. I try to stick to
> > the previous versions of the EDTF drafts except regarding the question
> > marks.
> >
> > This other approach would be the following, based on praxis in the 
english
> > language and other languages such as Swedish, for exxample. This e-mail
> > focuses on this suggestion. Let's consider the following sentence:
> >
> > "Would (not?) it be easier?"
> >
> > Here, the question mark without a right parenthesis on its right side
> > applies to everything on the left (of it). The question mark with a right
> > parenthesis on its right side applies to what is inside of the 
parentheses.
> > I consider this approach would be a good way to avoid mistakes when 
metadata
> > is stored because it reminds of the use of parentheses as in several
> > languages.
> >
> > My suggestion is thus a syntax such as:
> >
> > 2011-05-09? (* "?" applies to the whole date *)
> >
> > 2011-05?-09 (* "?" applies to 2011-05 *)
> >
> > 2011?-05-09 (* "?" applies to 2011 *)
> >
> > For short: A question mark without a right parenthesis immediately on its
> > right side is applicable to everything on its left side within the
> > expression. Easy, isn't it?
> >
> > Let's consider parentheses, now!
> >
> > 2011-(05?)-09 (* "?" applies to 05 *)
> >
> > 2011-(05-09?) (* "?" applies to 05-09 *)
> >
> > 2011-05-(09?) (* "?" applies to 09 *)
> >
> > For short: A question mark with a right parenthesis immediately on its 
right
> > side is applicable to everything within the parentheses. Easy, isn't it?
> >
> > These may be mixed in expressions such as:
> >
> > 2011?-05-(09?) (* The first "?" applies to 2011 and the second one 
applies
> > to 09. In other words, only the month is "sure". *)
> >
> > I consider that this would be quite straightforward and obvious to
> > understand. Furthermore, it would be easy to formulate in the BNF 
(thanks to
> > the placement of the parentheses) and easy to implement, too. It is not
> > counter-intuitive, either.
> >
> > Regards!
> >
> > [UTF-8?]Saašha,
> >


--

Edward C. Zimmermann, NONMONOTONIC LAB
Basis Systeme netzwerk, Munich Ges. des buergerl. Rechts
Office Leo (R&D):
  Leopoldstrasse 53-55, D-80802 Munich,
  Federal Republic of Germany
http://www.nonmonotonic.net
Umsatz-St-ID: DE130492967

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