W3C home > Mailing lists > Public > public-prov-wg@w3.org > June 2011

Simplicity (was: definition of derivation?)

From: Graham Klyne <GK@ninebynine.org>
Date: Wed, 29 Jun 2011 12:54:34 +0100
Message-ID: <4E0B127A.20509@ninebynine.org>
To: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
CC: public-prov-wg@w3.org
Luc,

I prefer Satya's simpler form.  I think it tells us what we need to know right now.

As I recall, we set out on this course of creating definitions so we could have 
some vocabulary to talk about a provenance model.  I think making such formal 
definitions at this stage (if ever) is not really helping us to make progress.

I understand that you would like a system with a level of ontological commitment 
that helps to power certain kinds of inference.  But it's really hard to back 
out of such commitments once they are baked in to a vocabulary, but relatively 
easy to extend a vocabulary compatibly to add commitments.  If a system is 
overcommited in ways that do not suit some potential users, they are forced to 
invent their own separate systems.  But if it is under-committed for some 
purposes, it is still possible to build upon it.

So, at this stage, I think we'd make faster progress if we focused on more open 
(less constrained) forms of definition, so we can more on to see how they can 
fit together.  It's in the more holistic context of seeing the vocabulary terms 
work together that I think we can start to see what additional constraints may 
be needed.

In my view, a measure of success of this group will be if it's output ecourages 
developers and publishers to make provenance available.  Given "a little 
semantics goes a long way", I think that ease of understanding and publication 
should trump power of inference.  We need developers and publishers to look at 
what we produce and to instantly think "that's easy, I can add that tomorrow". 
Anything that gets in the way of that will reduce our effectiveness as a WG. 
(Stephen Hawking, in the acknowlegements for his "A brief history of time", says 
he was advised that each equation in his book would halve its sales; I think we 
have a similar situation here concerning the degree of formality imposed in 
order to just understand the provenance vocabulary)

#g
--

Luc Moreau wrote:
>   Hi Satya,
> 
> I would not replace, but add it to the definition:
> 
> Derivation represents how stuff is transformed from, created from, or
> affected by other stuff. A thing B is derived from a thing A if the
> values of some invariant properties of B are at least partially
> determined by the values of some invariant properties of A.
> 
> Luc
> 
> On 06/29/2011 02:16 AM, Satya Sahoo wrote:
>>
>> Hi all,
>>
>> I broadly agree with Luc and Simon's definition, except I would 
>> replace /affected/ with /created from/, since a thing X may be 
>> affected by thing Y, but X may not be derived from Y. For example, 
>> cold temperature affects plant X, but plant X is not derived from cold 
>> temperature.
>>
>> Modified definition: "Derivation represents how stuff is transformed 
>> from or created from other stuff."
>>
>> Also, would like to point to the both the "derived from" and 
>> "transformation of" properties defined by the OBO Foundry Relation 
>> ontology [1], which is widely used in biomedical ontologies. 
>>
>> Thanks.
>>
>> Best,
>> Satya
>>
>> [1] http://www.obofoundry.org/ro/
>>
>> On Tue, Jun 21, 2011 at 9:31 AM, Graham Klyne <GK@ninebynine.org 
>> <mailto:GK@ninebynine.org>> wrote:
>>
>>     I prefer Simon's formulation.  A concern I had with the previous
>>     form was its dependence on a temporal element.  That temporal
>>     dependence may be a consequence, but I don't think it should be
>>     part of the definition.
>>
>>     #g
>>     -- 
>>
>>
>>
>>     Simon Miles wrote:
>>
>>         Paul, Luc,
>>
>>         I'm OK with the definition, but I think it could be simplified and
>>         clarified a little, and suggest:
>>
>>         Derivation represents how stuff is transformed from or affected by
>>         other stuff. A thing B is derived from a thing A if the values
>>         of some
>>         invariant properties of B are at least partially determined by the
>>         values of some invariant properties of A.
>>
>>         The reasons for this proposed revision:
>>
>>         1. "A was used (and therefore created) before B was created"
>>         means the
>>         definition of "derivation" is based on those for "use" and
>>         "generation". This property seems, in practice, necessitated by B
>>         having been determined by A anyway.
>>
>>         2. The first sentence mixes plural with singular, so it is
>>         unclear how
>>         many things a derivation relates.
>>
>>         3. The "in the real world" caveat seems unnecessary if
>>         "things" are
>>         defined to be explicitly about the real world. Moreover, if we
>>         decide
>>         to revise the definition of "thing" to cover more than the
>>         real world,
>>         then derivation would also have to be revised.
>>
>>         Thanks,
>>         Simon
>>
>>         On 20 June 2011 21:07, Paul Groth <pgroth@gmail.com
>>         <mailto:pgroth@gmail.com>> wrote:
>>
>>             Hi All,
>>
>>             What do people think of Luc's definition of derivation:
>>
>>             - http://www.w3.org/2011/prov
>>             /wiki/ConceptDerivation#Definition_by_Luc_.28in_terms_of_properties.29
>>             Things represent stuff in the real-world.
>>
>>             Definition of Derivation. A derivation represents how
>>             stuffs are
>>             transformed or affect each other in the real world.
>>
>>             A thing B is derived from a thing A if:
>>
>>             A was used (and therefore created) before B was created
>>             The values of some invariant properties of B are partially
>>             determined by
>>             the values of some invariant properties of A
>>
>>             James you seemed to suggest another way to define
>>             derivation or not
>>             define it all? Can you be more specific?
>>
>>
>>             Thanks,
>>             Paul
>>
>>
>>             ______________________________________________________________________
>>             This email has been scanned by the MessageLabs Email
>>             Security System.
>>             For more information please visit
>>             http://www.messagelabs.com/email
>>             ______________________________________________________________________
>>
>>
>>
>>
>>
>>
>>
> 
> -- 
> Professor Luc Moreau               
> Electronics and Computer Science   tel:   +44 23 8059 4487         
> University of Southampton          fax:   +44 23 8059 2865         
> Southampton SO17 1BJ               email: l.moreau@ecs.soton.ac.uk <mailto:l.moreau@ecs.soton.ac.uk>  
> United Kingdom                     http://www.ecs.soton.ac.uk/~lavm
> 
Received on Wednesday, 29 June 2011 12:59:26 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Thursday, 26 April 2012 13:06:32 GMT