RE: [BIONT-DSE] Inclusion versus exclusion criteria

> The data complexity of EL++ suggest strongly that a sensible
> reduction to SQL is unlikely (i.e., you'll need datalogesque rules as
> well).

[VK] The interesting question in my mind then is what is the additional
functionality achieved by these datalogesque rules that are not present in
SQL? The reason I ask is because today the major RDBMS vendors support
transitive closure operations and I was wondering if there is any other
functionality that is missing in SQL.

Also, what would be great is to get a concrete real world example which
illustrates the above. The example given by Kavitha, I believe has a SQL
translation. Getting such examples are crucial to showing the value of the web.

> Even logspace data complex logics can be tricky. The DL-Lite family
> is the paramount example and they can have an exponential blowup in
> the size of the query (since they need to intern parts of the tbox in
> the query, so each conjunct might expand, and then the permutations
> of the expansions must be added to the union of I
> recall :))

[VK] From a pragmatic point of view, in the context of a given application, 
this just needs to be done once. There are well defined RDBMS approaches to
create views, materialize them, develop indexing structures to achieve

For instance, I know that a common approach to using Snomed is to precompute
the "closure" and store it in a RDBMS.

So, the real world has figured out ways of dealing with these situations and
I am yet to see examples of how using semantic web technologies, will give them
the scalability and make their life easier.

> So, basically, large queries with large, connectd TBoxes will be
> challenging, requiring clever optimization of the rewriting. This
> isn't something you'll do by hand ;)

[VK] Can I have some real world examples which illustrate this?


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Received on Thursday, 13 September 2007 12:40:57 UTC