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Re: Changes to iCalender ontology to make calendar files diffable

From: Graham Klyne <gk@ninebynine.org>
Date: Wed, 24 Mar 2004 19:18:34 +0000
Message-Id: <>
To: Tim Berners-Lee <timbl@w3.org>
Cc: www-rdf-calendar@w3.org


When I have some time, I might have a look at generating patch files from 
my graph-diff.

(I *think* I can be sure of not generating falsehoods in this way, at the 
expense of a somewhat "brute-force" approach to finding possible 
node-matches after the obvious ones have been isolated.)


At 11:10 24/03/04 -0500, Tim Berners-Lee wrote:
>Ooops.  Sorry, No, Graham, [1] should have been to  "Diff, patch, update, 
>[1] http://www.w3.org/DesignIssues/Diff
>which points to an actual program
>[3] http://www.w3.org/2000/10/swap/diff.py
>The algorithm in diff.py is to find a mapping corresponding nodes in the 
>two graphs
>because they have the same URI or literal value or they are connected by 
>an [inverse]
>functional property to nodes which have already been mapped as corresponding.
>It isn't the pretty-printing-like algorithm which you use in [2].
>It only works on a subset of graphs which have are well labelled, but the 
>diff file has useful property that you can apply it to anything without 
>fear of
>generating falsehoods.
>The update language looks like for example
>[4] http://www.w3.org/2000/10/swap/test/delta/t2/patch.n3
>On Mar 24, 2004, at 6:45, Graham Klyne wrote:
>>At 16:36 23/03/04 -0500, you wrote:
>>>To make the graph labelled enough for doing a diff,[1], with calendar 
>>>data, here are the fixes I had to make (a copy of) to the ontology:
>>I didn't see a reference given for '[1]'.  If it's my graph-differencing 
>>function [2], I'd be interested to see the problem data, as my algorithm 
>>doesn't depend *entirely* on graph labels.  If not mine, I'd be 
>>interested to know of other approaches.
>>[2] http://www.ninebynine.org/RDFNotes/Swish/Intro.html#GraphDiff
>>Graham Klyne
>>For email:
>Graham Klyne
>For email:
Received on Wednesday, 24 March 2004 16:22:24 UTC

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