Dear David, (01)
-----Original Message-----
From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
[mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of David Whitten
Sent: 06 January 2015 21:54
To: [ontolog-forum]
Subject: Re: [ontolog-forum] knowledge base and DBs (02)
Notes and questions below. (03)
On Tue, Jan 6, 2015 at 4:19 PM, Matthew West <dr.matthew.west@xxxxxxxxx>
wrote:
> Dear David,
> You use categories, logic and rules in databases too. What is the type
> of sale? What is the maximum credit a client is allowed? (04)
This is a good point. (05)
Do you feel that the ability to categorize particular data in a database is
supported by the database infrastructure or must be provided by external
procedures or data ?
[MW>] The only categories a database know about are the tables. That is a
flat structure so there is no inherent support for subtype/supertype. You
can do anything you like in data, e.g. have a subtype/supertype table, but
then you need to provide the logic to process that correctly. (06)
When I speak of category support, I'm thinking of being able to define some
data as an instance of a particular category, and then possibly a hierarchy
of categories as sub-collections of other categories, and be able to find
all the data that can be categorized by any particular category without
replicating the entire hierarchy in the query. (07)
Maybe you could do that by having a fixed height of the category hierarchy,
requiring the hiearchy to be rooted, and storing the path to the root from
the current instance in a block of columns, treating the path as a series.
I suggest this because I don't know how much support SQL has for a column
that has a variable number of sub-parts/sub-columns.
[MW>] Yes, but all you really have is a foreign key, it does not know that
it is subtype supertype. Generally, using fixed hierarchies is frowned upon,
they almost never are really fixed. (08)
I know that SQL allows some logic (such as in the WHERE clause), but was not
aware that you could store negative information in the database, such as the
suit color was NOT Red, and NOT Plaid. I think of a database as solely
storing positive information (much as Propositional Logic system might
support)
[MW>] Nothing to prevent you having a table that lists the colours
particular suits are not, if that is your requirement. However, the default
is that absence is negation, i.e. it is not grey unless you have said that
it is. (09)
I didn't know SQL supported modal information such as what is "allowed for a
client".
[MW>] Again, there is nothing to stop you to have a table of what is
allowed, rather than what is. I am not aware of say OWL supporting modality
either explicitly. (010)
>
> A knowledge base does not need to be a collection of singletons, and
> generally is not. I expect a knowledge base to have a lot of
> classification and whole-part relationships, but you might think of
> them more in relation to what the whole-part relations were between
> rather than as a separate collection with the same structure relating
> different things. It is just that with a knowledge base you do not
> need to think about these things before you start, with a database you do. (011)
I can see how the definition of a knowledge base would need to mention this
dynamic nature of structuring.
[MW>] Not forgetting that we are both assuming a knowledge base as a formal
ontology of some sort in some ontology language such as OWL or KIF. (012)
Regards (013)
Matthew West
Information Junction
Mobile: +44 750 3385279
Skype: dr.matthew.west
matthew.west@xxxxxxxxxxxxxxxxxxxxxxxxx
http://www.informationjunction.co.uk/
https://www.matthew-west.org.uk/
This email originates from Information Junction Ltd. Registered in England
and Wales No. 6632177.
Registered office: 8 Ennismore Close, Letchworth Garden City, Hertfordshire,
SG6 2SU. (014)
>
> Regards
>
> Matthew West
> Information Junction
> Mobile: +44 750 3385279
> Skype: dr.matthew.west
> matthew.west@xxxxxxxxxxxxxxxxxxxxxxxxx
> http://www.informationjunction.co.uk/
> https://www.matthew-west.org.uk/
> This email originates from Information Junction Ltd. Registered in
> England and Wales No. 6632177.
> Registered office: 8 Ennismore Close, Letchworth Garden City,
> Hertfordshire,
> SG6 2SU.
>
>
>
> -----Original Message-----
> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
> [mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of David
> Whitten
> Sent: 06 January 2015 19:36
> To: [ontolog-forum]
> Subject: Re: [ontolog-forum] knowledge base and DBs
>
> Thank you Matt,
>
> This is an intriguing idea to me, that the number of individuals that
> have a particular structure is the defining characteristic of when to
> use a database or a knowledge base.
>
> Do you think that because a knowledge base is mostly a collection of
> singletons, that effectively using a knowledge base predisposes one to
> want to use logic, rules, and categories to describe it?
>
> David Whitten
> 713-870-3834
>
>
> On Tue, Jan 6, 2015 at 2:00 PM, Matthew West
> <dr.matthew.west@xxxxxxxxx>
> wrote:
>> Dear David and Alexander,
>> Hmmm. Well to my mind the biggest difference is not to do with
>> operations and logic, SQL is very competent. The key difference is
>> that a database has a structure that is defined at database
>> definition time, and data that is added at runtime. On the other
>> hand, a knowledge base has minimal structure, and is defined by the
>> type of knowledge base used. None of this has much to do with what
>> you can do with the different approaches, and a lot of things you can
>> do with either. A database is likely to be more efficient when there
>> are a lot of records with the same structure to be stored and
>> referred to. A knowledgebase is likely to be more efficient when
>> flexibility in structure
> is what is required.
>>
>> Regards
>>
>> Matthew West
>> Information Junction
>> Mobile: +44 750 3385279
>> Skype: dr.matthew.west
>> matthew.west@xxxxxxxxxxxxxxxxxxxxxxxxx
>> http://www.informationjunction.co.uk/
>> https://www.matthew-west.org.uk/
>> This email originates from Information Junction Ltd. Registered in
>> England and Wales No. 6632177.
>> Registered office: 8 Ennismore Close, Letchworth Garden City,
>> Hertfordshire,
>> SG6 2SU.
>>
>>
>>
>> -----Original Message-----
>> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
>> [mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of David
>> Whitten
>> Sent: 06 January 2015 17:07
>> To: [ontolog-forum]
>> Subject: Re: [ontolog-forum] knowledge base and DBs
>>
>> In my mind, one of the big differences between a database (db) and a
>> knowledge base (kb):
>>
>> a databases store information, and may actually include calculated
>> information that is dependent on the stored information. Basically,
>> a storage facility for known facts.
>>
>> a knowledge base includes all that is in a database but also includes
>> the activity of inference from information, and has a far more
>> sophisticated model of hierarchical categories of information. A
>> knowledge base also includes all the standard First Order Predicate
>> Calculus operations: AND OR NOT FORALL THEREEXISTS as well. Knowledge
>> bases handle infinite groups of facts as it were.
>>
>> Does anyone have something to add to this?
>>
>> Dave Whitten
>> 713-870-3834
>>
>>
>> On Tue, Jan 6, 2015 at 11:33 AM, Alexander Garcia Castro
>> <alexgarciac@xxxxxxxxx> wrote:
>>> Hi all, I am having some troubles explaining the difference between
>>> a DB and a knowledge base, can someone let me know the difference?
>>>
>>> --
>>> Alexander Garcia
>>> http://www.alexandergarcia.name/
>>> http://www.usefilm.com/photographer/75943.html
>>> http://www.linkedin.com/in/alexgarciac
>>>
>>>
>>>
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