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Re: Minus signs in ids -- n3.bnf

From: Petr Cimprich <petr@gingerall.cz>
Date: Wed, 5 Dec 2001 08:02:01 -0500 (EST)
Message-ID: <3C0E1A1A.6050305@gingerall.cz>
To: Tim Berners-Lee <timbl@w3.org>
Cc: Sandro Hawke <sandro@roads.org>, www-archive@w3.org
Tim, Sandro

Thanks for the reply. The escaping is a good idea, but it doesn't work 
in both ways. I mean that "-" in XML would be mapped to "__" in N3, but 
it likely remains "__" if converted back to XML. However, it's still 
better than to exclude names with "-" completely.

May be I'm wrong, but since operators are to be used as shorthands for 
properties and there is always at least one space between subject and 
verb, or verb and object, a hyphen in local names (something like 
"pref:local-name") should never be taken as operator. But it's quite 
possible I'm missing your idea of operators at all.

Anyway, I see that my former suggestion to change alphanumeric wasn't 
necessary. Instead, the following change would apply to local names only:

fragid ::= alpha alphanumeric* ;
fragid ::= alpha ( alphanumeric  |  "-" )* ;

Have a nice day,

Tim Berners-Lee wrote:

>Sandro passed on your message.
>Adding "-" to the ID characters is a problem, in that I wanted to reserve
>the usual operators for use as operators in some posisble future shorthand
>Another solution would be to have some form of escaping,
>such as mapping sequences of "-" into sequences of "_" in some way,
>such as taking a contiguous sequence of - and _,
>replacing  _ with 0 and - with 1, then adding a leading "1",
>taking what you have as a binary number, subtracting
>1 from the result, and then writing that many _ signs.
>The mapping is 1:1, and maps the simple case of - onto __
>and _ onto _.
>The only disadvantage is that those who co crazy with
>n consecutive occurrences of  - and/or _  in XML will pay for it
>in an even crazier 2**n long sequence in the N3.
>I'll put a note in the Notation3 document suggesting this.
>----- Original Message -----
>From: "Sandro Hawke" <sandro@roads.org>
>To: <timbl@w3.org>
>Sent: Tuesday, December 04, 2001 10:02 AM
>Subject: Petr Cimprich: n3.bnf
>>Tim, I think he's suggesting allowing "-" in n3 identifiers, which I
>>think you don't want because you want to keep it as a possible
>>operator.   I'll reply if I don't see some reply from you to him soon.
>>    -- sandro
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>>From: Petr Cimprich <petr@gingerall.cz>
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>>I have have written an N3 parser in Perl a while ago according to your
>>BNF def
>>I have an issue I have encountered during conversions to and from XML:
>>While XML allows to use a hyphen in names, it is prohibited in N3
>>localname. How about to change
>>alphanumeric ::= alpha | [0-9] | "_";
>>alphanumeric ::= alpha | [0-9] | "_" | "-";
>>Would it mind anything? Hyphen doesn't seem to have any special meaning
>>in N3.
>>Thanks a lot for your time,
>>- --
>>Petr Cimprich
>>Ginger Alliance
>>------- End of Forwarded Message

Petr Cimprich
Ginger Alliance
Received on Thursday, 6 December 2001 15:25:32 UTC

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