Hi,
I have some points about this proposal.
In my head a topic map is represented as a graph of information items
(defined by TMDM). For me the big advantage of topic maps is the
abstraction in the model. We dont spend any time on thinking about "how"
all our information items are connected. Therefor we created the
abstract model TMDM. A Topic plays a role in an AssociationRole which is
contained in an Association which may contain other AssociationRole.
(plays and contains are edges)
With that i can imagine a huge topic map graph of all those TMDM defined
information items.
But when looking at TMRQL, i have to change from a graph in my mind to a
bunch of tables which are interconnected via id's.
The proposal says:
"One of the inherent principles that is embodied in the views approach
is that every topic map object (topic, name, occurrence etc) has some
kind of system identity."
That is definitely true, from the view of a Topic Map Engine developer.
There has to be an identity for every information item.
But in my opinion it is not necessary for the user who works with topic
maps. The user who creates a query must be able to stay in his abstract
graph representation/imagination.
If the actual TMQL proposal fits to that needs is another question.
I researched about Graph Query Languages and subGraph Matching
(especially efficient approaches with neural nets).
Kal maybe you can convince me. That i can stay by the graph
representation in my mind and work with TMRQL.
How could i express the following query with TMRQL:
"Give me a subgraph of the TM, that contains a topic A, that has a path
to topic B and C."
The problem of this query is the "path" operator, which is often used in
Graph Query Languages. A path in a topic map is a chain of
topic->assocRole->assoc->assocRole->topic->assocRole->assoc->......
Such queries are very common. For example in semantic enhanced search
engines, where you can enter the words A, B, C. You'll get all
occurrences of the subgraph that contains A, B, C as result.
just my 2c
Stefan
Kal Ahmed wrote:
Dear all,
Graham and I have published a paper proposing a different approach to
topic map querying. Rather than define a new query language, we define
a relational view of the topic map data model which can then be
queried using a standard relational query language such as SQL.
Full details, including worked examples of the TMQL Use Cases which
run on TMCore05 can be found at
http://www.networkedplanet.com/download/TMRQL.pdf
We would like this document to be taken as input from Networked Planet
Limited into the ISO TMQL standardisation process.
Best regards,
Kal Ahmed
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