Re: [ontolog-forum] master data vs. ontologies

[Thomas Johnston <tmj44p@xxxxxxx>]

Steven,

It seems to me that the structure of tables in a relational database is mathematical; they are relations. The interpretation of those structures is not formally expressed in databases or their catalogs; it is informally expressed by giving names to the tables.

What those tables are are types, and their rows are tokens of those types. Every row in a Customer table is a customer, one instance/token of the type Customer.

When the types which appear as the tables, columns and domains in relational databases are expressed formally, so that automated inferencing can be done on them, then, and only then, do we have an ontology for those databases.

So the ontology for a relational database -- if only we had one! -- would be a set of types and a set of statements about those types. The central kind of statement is the "X IS-A Y" statement, and when all the Xs and Ys have been related that way, we have a taxonomy. When other statements about those types are added to the set of statements about them, they constitute an ontology for which that taxonomy is the "backbone". Vagaries of terminology aside, I would hope that most ontologists would agree with this.

On Monday, February 16, 2015 1:52 PM, Steven Ericsson-Zenith <steven@xxxxxxx> wrote:

Is it not the case that an RDBMS ontology is an SQL schema? And does not an SQL schema ensure the validity of instances of data?  I know that it does not, but it surely was intended to by Codd. Tables in an RDBMS are simply a form of structured memory. No?

Steven

On Mon, Feb 16, 2015 at 1:28 PM, Thomas Johnston <tmj44p@xxxxxxx> wrote:

Ravi,

In what I think is fairly standard use of terminology, I would say that a table in a relational database has the mathematical structure of a time-varying relation on the Cartesian Product of that table's columns. To give an interpretation to those mathematical objects, i.e. to interpret them as representing types (ontological kinds), the best we can do  is to give those constructs names -- hence Customer tables, Product tables, etc. 

But the names mean nothing to the DBMS. So another way to look at ontologies in the context of relational databases is this: once the catalog entries for tables, columns and domains in relational databases are associated with ontologies that the RDBMS can manipulate, then those names will be more than names. They will be objects on which inferencing can be performed. When databases of the future can do that, we will have something very powerful indeed.

However, terminology in both the field of formal ontologies, and indeed in IT data management, is often imprecise. So it's hard to agree or disagree with your points, and I hope I haven't misunderstood you. 

Let's see what others have to say.

On Monday, February 16, 2015 11:45 AM, Ravi Sharma <drravisharma@xxxxxxxxx> wrote:

Tom

Quoting

"Ontologies are about the types themselves, not their instances."

Hence Ontology are to be compared to or mapped to Metadata of Master Data and not  to the Instances of Master Data (Values of Master Data).

Is it not correct to think of Meta-model of the MDM (e.g. tool) as being something akin to E-R Diagrams / Models but not about tables and columns but instead about Master Data table type and relationship type and this in turn being mapped to Things and Relationships in ontology domains?

Regards,

Ravi

On Mon, Feb 16, 2015 at 10:43 AM, Thomas Johnston <tmj44p@xxxxxxx> wrote:

Erick,

Master data, like all data managed in relational databases, is about instances of types. Rows in a Customer table, for example, are instances of the type Customer. Rows in an ICD10 table are instances of IC10 codes.

Ontologies are about the types themselves, not their instances. They are about, e.g. the type Customer being a subtype of the type Related Party. When the types are related in an IS-A hierarchy, that is a taxonomy which is part of an ontology. Other relationships among types flesh out the ontology, supplementing the taxonomy. For example, an agent/patient relationship might relate Vendor to Customer.

Ontologies are often graphically shown as a network of nodes and arcs -- boxes with lines between them. I think most ontologists would agree with me that this is just a matter of convenience, a graphic way to depict logical relationships among types. Technically speaking, the nodes and arcs represent objects and predicates in a second-order predicate logic.

So, in my opinion, while there is a great deal to say about master data, and about ontologies, resulting in a lot of potential for confusion, there is no more fundamental way to distinguish them than by saying that ontologies are to master data as types are to instances (also called "tokens").

And since relational databases do not manage types at all -- or, at best, only in a primitive way -- you can pretty much assume that commercial databases do not include ontologies at all.

Regards,

Tom Johnston

2/16/15

On Thursday, February 12, 2015 3:30 AM, Erick Antezana <erick.antezana@xxxxxxxxx> wrote:

Hi,

I need some help to better define the line (sometimes apparently grey) between master data and ontologies.

We all, at least in this forum, know that there are several definitions for both terms. 

I guess most of us are familiar with Gruber's one: a formal specification of a shared conceptualization.

In the case of master data: 

- 'entities, relationships, and attributes that are critical for an enterprise and foundational to a key business process and application systems' 

or among others: 

- 'is the consistent and uniform set of identifiers and extended attributes that describes the core entities of an enterprise'.

What are the key components to differenciate master data and ontologies? 

What is common to both artefacts?

From what I have seen, sometimes the border between them seems indeed relatively grey... which seems to be the product of having ontologies as glue components of disparate master data. Also, there seems to be a continuum between them (as in the databases and knowledge base thread in this forum). Anyway, I would appraciate reading your thoughts about it.

Cheers,

Erick

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--

Thanks.
Ravi
(Dr. Ravi Sharma)
313 204 1740 Mobile

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