Notes on Ontology Tools

While reading about ontology tools[2], I found a tool (Hozo) that supports "roles" explicitly (see #17 of the original Existential Programming epiphanies, and a role case study). Hozo separates "role concepts" from "basic concepts"; however, the tool allows each role attribute to be mapped to a basic concept attribute. I see that an existential programing language should allow "roles" to "inherit" from its "roleholder" ala subclass inheritance without actually being a subclass. [Hmmm... in an existential programming language, where all "classes" were effectively mixins anyway, how would roles be different?]

(click to enlarge)

From[3], seeing CYC's concepts of #$is-a versus #$genls reminds me of a discussion I had back in 2002 with the Protege 2000 folks at Stanford who produced a Wine ontology, where I wanted to have no distinction between classes and instances because I wanted a hierarchy like wine->reds->shiraz->Rosemont->vintage94->bottle#123. I.E. something considered a leaf on the tree might later be a node with children itself. Protege would only allow variables to take on values that were "instances" and I wanted to put "chardonnay" (a subclass) as the value of a "wine variety" property. SO, is there no difference between classes and object, or should the "value" of an attribute be able to contain a "class" reference??

From[4], seeing the Semantic Web's layer cake, I see that my ideas about recording "says who?" and "how reliable are you?" seem similar to the "trust layer". [Ed. note 11-23-07: like maybe you read this stuff years ago and it was the subliminal seed of this "says who" epiphany?]

[1] Tutorial on Ontological Engineering: Part 2: Ontology Development, Tools and Languages, Riichiro Mizoguchi, 2004
[*** Get the PDF here ***]
[2] ibid, Page 14, Fig. 2.
[3] ibid, Page 15, Section 3.1
[4] ibid, Page 23

Philosphers Toolkit

In the handy Philosopher's Toolkit book[1], there is a section[2] explaining the difference between "categorical" statements and "modal" statements. In reading it, I see that some of my intuitions about the assumptions implicit in the object oriented programming model (e.g. "what time period was this data true?", "says who?", etc) were actually a recognition that OO models contain "categorical" assertions and do not (without explicit programming) support "modalities". Temporal modality, intensional logics, etc. E.G. there is no "date range" associated with each attributes value.

In another section[3], Leibniz's law of identity (which says that A is the same "thing" as B if all attributes of A are equal to their corresponding attributes in B), relates to my epiphany #5. But which set of properties are necessary/sufficient to claim a match? It depends on the ontology. Consider "cross temporal identity"...the river of today vs the river of yesterday..."molecules" vs "water". For people, the properties are often not used to identify them, but instead a "continuity of memory" connects yesterday's YOU vs today's YOU.

In another section[4], the difference between "types" and "tokens" are discussed. Type is an analog of "class". Token is an analog of "object". Type-identical is an analog of "instanceOf". Token-identical is an analog of "address-of(A) == address-of(B)".

[1] The Philosopher's Toolkit, Julian Baggini and Peter S. Fosl, Blackwell Publishers, 1st Ed., 2003, ISBN: 0631228748
[2] ibid, section 4.4
[3] ibid, section 3.6
[4] ibid, section 4.17

Ontology Merging Strategy

Summarizing the posts from yesterday, there is a general problem of "things" in one ontology/data model not mapping (in a definite way) to "things" in another model. How to support (or even automate) mapping from one model to another? I.E. how to facilitate "transformation" from one "basis" to another?

A strategy at the heart of an existential programming language could be to reduce entities to their most atomic level: semantic relations between an entity and a single attribute. Use "identity" algorithms to reconstitute these atoms into "things".

A new language that did this and integrated multiple sources of data (OO data, E/R relational data, semantic networks, web-search-results) could create a single seamless framework and data continuum.
[Ed. Note: as found 10/29/07, others have had similar ideas.]