RE: [xdi] Groups - On the extension of $word set in XDI (Draft-Contrib-O

Just to second Markus’ though below, I found the idea of “double dollar” for XDI variables attractive. There’s not yet much history around that idea, but I think we should start experimenting with it to see how it works.

=Drummond

From: markus.sabadello@gmail.com [mailto:markus.sabadello@gmail.com] On Behalf Of Markus Sabadello
Sent: Monday, March 17, 2008 9:27 AM
To: Giovanni Bartolomeo
Cc: xdi@lists.oasis-open.org
Subject: Re: [xdi] Groups - On the extension of $word set in XDI (Draft-Contrib-OASIS-XDI-dollar-words-v03.pdf) uploaded

Hmm I can think of two possible solutions:

1) Always require a subsegment for the number, i.e. only allow $any$1, $any$2, etc. but never $any alone. This way you avoid ambiguity. Or
2) Use something else for the variables, something that never occurs in your knowledge base. As far as I know $$1, $$2, $$3, etc. was previously used for variables in XDI.

Markus

On Mon, Mar 17, 2008 at 1:32 PM, Giovanni Bartolomeo <giovanni.bartolomeo@uniroma2.it> wrote:

Hello Markus!

At 23.55 15/03/2008, Markus Sabadello wrote:

What would you think about adding a number to that variable, so you can use that feature more than once in a query? For example $any$1, $any$2, etc.

Actually I've thought at this possibility; which is really useful; this pave the way to n-variables query like the following:

=markus
    $get
       /
        $any$1
                 $is$a
                           @uniroma2+professor
        $any$1
                 +age
                          $any$2
        $any$2
                 $greater
                          "60"

get all uniroma2's professors older than 60 yo; tell me how old are them.
Unfortunately the inconvenience I see is that this way the matching pattern rule is broken, i.e. there is ambiguity related to whether "$1" is a pattern to match or an identifier for a variable: The following statements

=markus
    $get
       /
            =giovanni
               $any$1
                   "giovanni.bartolomeo@unroma2.it"

may mean "unify $any with the first subsegment of the predicate whose second segment is $1 and whose object is giovanni.bartolomeo@uniroma2.it", that's my first email.

I'm trying to work out a solution for this since 5 days.. but it didn't has arrived yet!
Suggestions very welcome!!! :-)

Giovanni

One advantage of this would be that the brackets wouldn't be necessary (thus keeping the syntax simple), since there would be implicit AND relationships between statements that use the same variable, and implicit OR relationships between those that don't.

Let me try to give an example to show what I mean:

=markus
    $get
        /
            =giovanni
                +friend
                    $any$1
            $any$1+age
                $lesser
                    "40"
            =giovanni
                +brother
                    $any$2
            $any$2+age
                $greater
                    "25"

This asks for all of Giovanni's friends younger than 40, and for all of Giovanni's brothers older than 25:

=giovanni/+friend/=Piergiorgio
=piergiorgio+age/$type$xsd$number/"25"
=giovanni/+friend/=mcoil
=mcoil+age/$type$xsd$number/"28"
=giovanni/+brother/=marco
=marco+age/$type$xsd$number/"30"

What do you think?

Markus

On 13 Mar 2008 10:59:13 -0000, < giovanni.bartolomeo@uniroma2.it> wrote:

New $words added: $and, $or, $any, $all; replaced weak order

relationship operators with composition of atomic $word operator ($equal,

$lesser,

$greater, $or); replaced $equals with $equal. Assumed that both subject and

object

in a XDI statement can be XDI documents.

-- Giovanni Bartolomeo

The document revision named On the extension of $word set in XDI

(Draft-Contrib-OASIS-XDI-dollar-words-v03.pdf) has been submitted by

Giovanni Bartolomeo to the OASIS XRI Data Interchange (XDI) TC document

repository. This document is revision #2 of

Draft-Contrib-OASIS-XDI-dollar-words.pdf.

Document Description:

This document propose the extension of $word set in order to introduce

concepts like equivalence, order and numbers in XDI; as well as Boolean

operators and query keywords

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http://www.oasis-open.org/apps/org/workgroup/xdi/document.php?document_id=27547

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http://www.oasis-open.org/apps/org/workgroup/xdi/download.php/27547/Draft-Contrib-OASIS-XDI-dollar-words-v03.pdf

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