Semantic Web, Bibliographic Ontology, UMBEL

UMBEL as a Coherent Framework to Support Ontology Development

There are multiple ways to represent the World we live in. Someone will think about something in a way, where someone else next to him will think about the same thing in another way. They will think about it in different ways: different characteristics, different ways to interact with it, different ways to use it, different ways to think about its composition, its relations with other things, and so on.

What is nice is that probably all of these different ways to think about this thing are good: after all, there are many ways to think about the same thing. It is this characteristic of thinking about things in different ways that leads to innovation.

But innovation is also not a game where anything goes. Things that work in the real world and in real ways need to adhere to certain rules, concepts, principles and theories. Continued innovation requires working within these coherent frameworks of natural relationships and order.

So, while a beautiful thing is that we can create new frameworks to think about things differently, not all of those frameworks work as well as others or make sense.

While it is conceivable that one could suppose any new framework or to think about things differently, frameworks that are actually useful should, among other things:

  1. Make sure the development of innovations within the framework is coherent
  2. Make sure the development of innovations within the framework is in context
  3. Help coordinate the development of projects and the cooperation of agents that work on these projects in order to achieve (1) and (2).

What seems clear to me is that the lack of any of (1), (2) or (3) makes innovations difficult and/or less powerful and less useful.

Why Would the Development Of Ontologies be Different?

The Semantic Web is often seen as a place where people describe things in multiple ways and where these things are more or less magically related together. For example, if you cant properly describe something, you only have to create a new ontology, or to extend an existing one, and to publish it, et voil!

The more I work in this field, the less I believe in this.

Remember my first point? People tend to think about things in different ways. The same logic applies to the development of ontologies (particularly in the development of ontologies!). Two ontologies, intended to describe the same things, can describe them in totally different ways. So, while some of the magic is that both ontologies can perfectly describe these things but only in different ways, there are other aspects that are not magical at all.

The problem here is to have at least one framework that helps people to develop ontologies such that the:

  1. Developed ontologies remain coherent
  2. Developed ontologies are in context
  3. Coordination of the development of ontologies and the cooperation of the agents working on these ontologies projects is effective to achieve goals (1) and (2).

This construct looks familiar, doesn’t it?

What I am proposing here is to use UMBEL as a coherent framework for ontology development. I am not saying that other frameworks can not play a guiding role in ontology development. But I am saying two things. First, some form of reference framework is necessary. And, second, truly useful frameworks must also be consistent and coherent.

What I am stressing here is the importance of conceptual frameworks to develop ontologies that can be used by people, companies and systems to properly and efficiently exchange data; and at some level, to reason over this data, too.

I think that the only way to do this in an efficient way is by grounding ontologies in such conceptual frameworks.

The ultimate goal is to make data exchange and data reasoning effective to people, organizations and systems that consume this sea of data. And I believe that it is not possible to achieve without grounding these efforts in a coherent, conceptual framework.

An Example at Work

Nothing is better than an example to shows the potential of UMBEL as a coherent framework to develop, and cross-link, ontologies.

Let’s take the Bibliographic Ontology as an example, which we just cross-linked to UMBEL in yesterdays version 071 release. (Among a dozen other key ontologies; the list is getting pretty cool!)

The goal is to link BIBO classes to UMBEL subject concepts. The linkage is done using three properties: owl:equivalentClass, rdfs:subClassOf and umbel:isAligned.

But firstly, what is the goal here? We try to do two things when linking such ontologies to the UMBEL framework:

  1. To make sure the ontology (BIBO) is coherent and consistent with other existing ontologies that are linked to the framework (other such ontologies could be FOAF, SIOC, etc.)
  2. To make sure that the design choices of the developed ontology are consistent with the design choices of the framework, and the other ontologies that are linked to that framework.

Both points try to help achieve a grander vision: trying to make the semantic Web a little bit more coherent and easy to use and understand.

The BIBO Linkage

This figure shows how BIBO classes have been linked to UMBEL subject concepts in a set-like schema (click to enlarge the schema):

This schema shows what set belongs to what other set. That way, we can quickly notice that bibo:Patent is equivalent to umbel:Patent. We can also see that both classes belongs to (sub-class-of) bibo:Document, umbel:PropositionalConceptualWork and umbel:ConceptualWork, etc.

We have to keep one thing in mind that we made clear in the UMBEL technical documentation: UMBEL has its own view of the World. UMBEL’s subject concept structure is its view of the World. So these linkages are consistent within the UMBEL framework. Now, let’s continue.

The Context

Remember the three points above? What we have done here is to put BIBO in context. The context is created by the UMBEL conceptual framework. Once this is done, we can check for the coherence between BIBO, UMBEL and all the other ontologies that are linked to the framework.

The figure below shows the context created by UMBEL for BIBO, FOAF and SIOC (click to enlarge the schema):

Considering the current description of these three ontologies, we know that bibo:Document is equivalent to foaf:Document. But there exists no relationship between these two classes and sioc:Item and sioc:Post.

Intuitively we know that there are some relationships between all these classes (at least based on their label). We also have to keep in mind that it is not because a description is not defined (in RDF) that this description doesn’t exist (this is the open world assumption).

That being said, the figure above shows how UMBEL can help us to find such “non-described” relationship between classes of different ontologies. By contextualizing these three ontologies we now find that all these classes are sub-classes of umbel:ConceptualWork. We also know that some sioc:Post belongs to umbel:PropositionalConceptualWork (things written), just like some bibo:Document and foaf:Document stuff.

This means that this linkage — this contextualization — of external ontologies now gives us a common ground to play with: umbel:ConceptualWork. By querying this subject concept we can come up with a full range of related things: BIBO, SIOC and FOAF stuff.

For example, take a look at the section “Narrower External Classes” of the umbel:ConceptualWork detailed report and extend the list of external classes (click on the All Classes . . . link). All these things are conceptual works. This fact is explicated by UMBEL even if no relations, or a small number, is described in these ontologies, related to the other ontologies. Also take a look a the list for umbel:PropositionalConceptualWork.

This also shows the coherence of the design of each ontology.

The Coherence

So, once we have the context in place, we are on our way to achieve coherence. UMBEL is 100% based on OpenCyc and Cyc, which are internally consistent and coherent within themselves. We thus use these coherent frameworks to make the mappings to external ontologies coherent, too.

The equation is simple:

“a coherent framework” + “ontologies contextualized by this framework” = “more coherent ontologies”

This context and this coherence helps us to develop ontologies in two ways:

  1. It helps us to make sure the design of an ontology is good
  2. It helps us to make sure the designed ontology is coherent with other existing external ontologies

For example, when I linked BIBO classes to UMBEL subject concept classes, I found that a bibo:Series was a sub-class of umbel:ConceptualWorkSeries. Then I found that bibo:Periodical was the same thing as a umbel:PeriodicalSeries. However I had an issue: a bibo:Series was a sub-class of bibo:Collection and bibo:Periodical was also a sub-class-of bibo:Collection. Then I found that umbel:PeriodicalSeries was a sub-class of umbel:ConceptualWorkSeries. Then the question arose: why bibo:Periodical is not a sub-class of bibo:Series instead of bibo:Collection? This is what I will propose for the next iteration of BIBO.

Now, what about this helping to increase the coherence between external ontologies?

One good example I have is related to SIOC and FOAF. When I linked SIOC to UMBEL, Kingsley asked me why I didn’t link sioc:Item. My answer was simple: I cant do this since if I make this linkage, the coherence of UMBEL will be disturbed. The problem was that sioc:Item was a sub-class-of foaf:Document. But considering sioc:Items definition, and foaf:Documents definition and linkage to UMBEL, by making the linkage of sioc:Item to UMBEL would create some incoherence in the framework because of its relationship with foaf:Document.

From this discussion with Kingsley, this thread appeared on the SIOC mailing list, and the link from sioc:Item to foaf:Document has been removed.

These are the two general cases where UMBEL, as a coherent framework, can help the development of ontologies.

So, by achieving points (1) and (2), we are on the way to achieve point (3): the coordination of the development of ontologies and the cooperation of the agents working on these ontologies projects is effective to achieve goals (1) and (2).

The Final Mapped Relations

So, after application of this process and thinking, here are the UMBEL-BIBO mappings:

You can look at Appendix A to the UMBEL technical document (PDF or online); additionally you will see similar mappings for the existing dozen or so ontologies presently mapped to UMBEL. In combination, these give us the ability to Explode the Domain!

Descriptive Subject Concepts: Icing on the Cake

All of the description above relates to the mapping between the BIBO and UMBEL ontologies (and therefore other external ones). But, of course, we also now have the full scope of UMBEL subject concepts that we can also now apply to describe what the actual BIBO citations are about.

So, while we have structural ontology relationships that can be leveraged, we also now have a common vocabulary to describe the subject matter of what these citations are about. Use of these UMBEL subject concepts now allow us to cluster and retrieve citations by subject matter.

In this manner, UMBEL becomes a consistent tagging vocabulary for describing what citations and references are about. Want everything about weaving or galaxies or opera or anything, for example? Simply characterize your citations by appropriate UMBEL subjects and then use them as part of your retrieval filters.

This makes clear that UMBEL is some kind of Hydra: it can be used as a conceptual framework to help make ontologies (vocabularies) coherent and consistent, and at the same time, it can act as a conceptual description framework that describes the “matter” of things. This means that a subject concept can describe the “nature” of a thing and the “matter” of another thing at the same time.

Conclusion

UMBEL is becoming a wonderful tool that can be used in many ways. It is a vocabulary that is instantiated in a subject concept structure. It can be used not only to categorize things and to help find things, but also to define things, and to develop ontologies that define other things. We are on our way to achieve these three goals:

  1. Develop ontologies that are in context
  2. Develop ontologies that remain coherent
  3. Coordinate the development of ontologies and the cooperation of the agents working on these ontologies projects sufficient to achieve goals (1) and (2).

As usual, I’d like to thank my UMBEL co-editor and colleague, Mike Bergman, for his discussions and assistance on this material.

Semantic Web, UMBEL

UMBEL version 071 Released

We have just released a new version of UMBEL (v 071). This new version is based on a new version of OpenCyc that has been updated with the latest knowledge base version 5014. This is the latest version of OpenCyc they released after we met Cycorp and the Cyc Foundation a couple of weeks ago in Austin. In the meantime we also fixed some things and enhanced the UMBEL concept structure.

Here is the list of changes and fix:

  • The UMBEL subject and abstract concept structure is based on OpenCyc kb5014
  • The UMBEL namespaces changed
  • UMBEL subject concepts now link to OpenCyc classes and individuals
  • The UMBEL generation scripts now uses the OpenCyc external IDs
  • Duplicated lines in the file umbel_cytoscape_vXYZ.csv have been removed
  • The linkage of BIBO to UMBEL has been completed
  • The linkage of FOAF and SIOC to UMBEL has been revised
  • The encoding of the character “%” in the named entities dictionaries N3 files has been fixed
  • The UMBEL technical documentation has been updated according to this list of changes.

Now lets talk about some major changes of this new release.

New UMBEL namespaces

We changed the UMBEL namespace URIs to be more consistent moving forward. Here is the fuller rationale:

“Here are the URIs of the namespaces used to describe the UMBEL Ontology, the subject concepts structure, the named entities defined in UMBEL and the semsets for both the subject concept classes and named entities.

The folder structure of these classes of URIs has been generalized to meet the design goals of using UMBEL with domain extensions. The portion “/umbel/” in the URIs is a placeholder for the name of these extensions. Each extension, including UMBEL itself, will share the same identification structure. An example for a ‘Foo’ domain ontology at an alternative example.com domain using the “/foo/” folder extension is shown in the table below.

The UMBEL Ontology vocabulary URI uses a “hash URI” for convenience purposes. This facilitates the retrieval of the document of the descriptions of the vocabulary for tools that consume such documents. However considering the size of the subject and abstract concepts descriptions files, the named entities and semset files, we choose to use “slash URIs” so that consumer tools do not have to download the description of all subject and abstract concepts, named entities and semsets descriptions when they request the description of one of these resources.”

The new namespaces are defined as:

Name

Abbreviation

URI

UMBEL Ontology

umbel:

http://umbel.org/umbel#
Subject Concepts

sc:

http://umbel.org/umbel/sc/
Abstract Concepts

ac:

http://umbel.org/umbel/ac/
Named Entities

ne:

http://umbel.org/umbel/ne/
Semsets

semset-xyz

http://umbel.org/umbel/semset/xyz/
Example, English semset

semset-en

http://umbel.org/umbel/semset/en/
FOO Ontology (a domain ontology based on UMBEL)

foo:

http://example.com/foo#

We now consider these new URIs as “frozen”. So please update your application with these new URIs.

UMBEL subject concepts that link to classes and individuals

In some edge cases, UMBEL considers that an OpenCyc individual is a subject concept or an abstract concept. This means that not only OpenCyc classes can be selected to be UMBEL subject concepts, but OpenCyc individuals can be as well. The definitions of UMBEL subject concepts, abstract concepts and named entities guide how the corresponding OpenCyc collection (“class”) or individual is treated. If an UMBEL subject concept is related to a OpenCyc collection (“class”), then the linkage between these two resources will be done with the property owl:equivalentClass. If an UMBEL subject concept is related to a OpenCyc individual, then the linkage between these two resources will be done with the property owl:sameAs. Check the volume 2 to know what we consider as subject concept, abstract concepts and named entities.

Use of OpenCyc classes’ external IDs

UMBEL subject and abstract concepts names have been used for convenience only. When a new version of UMBEL is created, the “external IDs” of the OpenCyc classes are used to link these classes to UMBEL subject and abstract concepts. That way, if their naming conventions change from an OpenCyc version A to a version B, then we are still able to update the proper UMBEL concepts according to their new OpenCyc definitions. Note that the OpenCyc external IDs are only used when we create a new version of UMBEL. Otherwise the URIs of the UMBEL subject and abstract concepts use the “human readable” labels to refer to the concepts.

Linkage between OpenCyc and UMBEL

We have to note that OpenCyc added linkage from the OpenCyc classes to the UMBEL subject concepts classes. This means that if someone dereferences OpenCyc classes URIs, they will have a reference to UMBEL subject concept classes via the property owl:sameAs.

Still to come

While much progress has been made in this new version 071, there are some pending issues and tasks not in the current release:

  • Complete Web service and endpoints release (forthcoming in a few days)
  • Re-inclusion of company provinces, states and territories
  • Automatic instance checks to ensure better coverage of more specific concepts in the ontology.

We are continuing to work out test and automation procedures with Cycorp and will incorporate these improvements as well in subsequent releases.

Conclusion

This new release is one more step in the good direction. UMBEL is getting more and more stable. Its relation to OpenCyc is stronger and stronger. And its linakge to external ontologies is bigger and bigger. Please report any issues, comments or suggestions on the mailing list.

Semantic Web, Zitgist, UMBEL

Starting to Play with the UMBEL Ontology

 

I am really proud to announce the first public release of the UMBEL Ontology and its subject structure after one year of hard work with Mike.

As UMBEL is introduced in the UMBEL Technical Documentation:

“UMBEL (Upper-level Mapping and Binding Exchange Layer) is a lightweight ontology for relating external ontologies and their classes to UMBEL subject concepts. UMBEL subject concepts are conceptually related together using the SKOS and the OWL-Full ontologies. They form a structural ‘backbone’ comprised of subject concepts and their semantic relationships. By linking external ontologies to this conceptual structure, we explode the domain of the linked classes by leveraging this conceptual structure.

UMBEL defines “subject concepts” as a distinct subset of the more broadly understood concept such as used in the SKOS/OWL-Full controlled vocabulary, conceptual graphs, formal concept analysis or the very general concepts common to many upper ontologies. We define subject concepts as a special kind of concept: namely, ones that are concrete, subject-related and non-abstract.

UMBEL contrasts subject concepts with abstract concepts and with named entities. Abstract concepts represent abstract or ephemeral notions such as truth, beauty, evil or justice, or are thought constructs useful to organizing or categorizing things but are not readily seen in the experiential world. Named entities are the real things or instances in the world that are themselves natural and notable class members of subject concepts. More detailed distinctions are provided under Terminology and Definitions below.”

Mike Bergman wrote a really good introduction blog post about UMBEL that lists all the supporting material and services that exists to get starting with UMBEL.

In this blog post I will write about one example that shows how to leverage UMBEL in two different ways: (1) how to use UMBEL to “explode the domain” of an existing ontology and (2) how to use UMBEL when an ontology doesn’t exist to describe a certain domain. I will also write other blog posts in the coming days to show more ways to leverage UMBEL in different settings and how to use it to solve other kind of real world problems.

Some of this new material will begin to hint at Zitgist’s own plans for using UMBEL.

Linking FOAF to UMBEL to explode its domain

How many times have people tried to use FOAF to describe organizational entities? In the end, everything ends up being assigned to foaf:Organization. A company, a NGO, or any other kind of organizations were all foaf:Organization(s) or foaf:Group(s). In most cases the result was unsatisfactory and everything ended up being the same “classification”.

But I don’t want to describe a business as an “Organization”, or a NGO as another “Organization”. They are two quite different concepts, even if the upper concept that links them is an “Organization”. However, there are no ontologies (that I know of) that describe businesses and NGOs; and FOAF is not expressive enough to do that distinction. However, is it FOAF’s goal to be that expressive? Possibly; but not in its current state. So what we want here is to extend it: to explode its domain!

And, it is what we will do with UMBEL.

The goal is to link FOAF classes to UMBEL subject concepts so that we can extend FOAF’s classes with more general and more specific concepts such as Business and NGO.

If you take a look at how the FOAF ontology has been linked to UMBEL, you will notice that a foaf:Organization is equivalent to an sc:Organization. Note: the linkage of external ontologies classes is consistent within UMBEL. It is UMBEL’s view of the World.

Let’s take an example to show what I mean. What I want is to describe the Zitgist LLC business; to describe it as a business, and not an organization. However I want to be able to re-use properties described in other ontologies to describe this business. So, here is an example of how I can describe this company using a UMBEL subject concept and external ontologies properties:

<http://zitgist.com/about/> a sc:Business ;

foaf:name “Zitgist LLC.” ;

foaf:birthday “2006-10-20” ;

foaf:logo <http://zitgist.com/imgs/zitgistlogo2_110_55.gif> ;

foaf:fundedBy <http://www.openlinksw.com> ;

bio:olb “””Zitgist provides quality Linked Data products and services. Linked Data is based on open standards to interconnect any form of relevant information on demand and in context. Zitgist’s capabilities range from the consumer Web plug-in zLinks to enterprise linked data transformation and deployment. Our expertise spans from data, standards and protocols to tools, user interface design, and scalable architectures. Zitgist innovation helps make the connections that matter. Let us show you how our approach to Linked Data can bring the power of the network effect to your data assets and global information.”””@en ;

foaf:based_near [ geo:Point [geo:lat “42.455”, geo:long “-71.218”] ] ;

foaf:homepage <http://zitgist.com> ;

foaf:made <http://umbel.org/about/> ;

foaf:made <http://browser.zitgist.com/about/> ;

foaf:made <http://pingthesemanticweb.com/about/> ;

foaf:made <http://musicontology.com/about/> ;

foaf:made <http://bibliontology.com/about/> ;

foaf:made <http://talkdigger.com/about/> .

As you can notice with this example, Zitgist is defined as a sc:Business. Well, you are probably wondering what is a sc:Business? Let’s take a look at the subject concept’s detailed report: sc:Business.

The next question is: why can I use all these properties to describe a sc:Business? The quick answer is because foaf:Organization is linked (equivalent to) sc:Organization and that sc:Business is a sub class of sc:Organization. You can read the proof here; and check the figure below that shows the inference path that leads us to this result.

(Note: this is what we refer to: exploding the domain of FOAF)

Analyzing a SC with the Detailed Report

The Detailed Report web service tool helps users to check which external class is linked to which subject concept and the nature of the linkage. Additionally it helps people to know what properties can be re-used to describe an individual of that class. Here is a quick overview of what information can be accessed when using this detailed report tool. Let’s take the sc:Business detailed report page:

Named Entities

The Named Entities section lists a couple of named entities that belong to this subject concept class. These are direct, or inferred, Yago named entities that belongs to this subject concept.

More General External Classes
The More General External Classes section lists the external super-classes linked to this subject concept. So we can quickly notice that a sc:Business is a foaf:Organization, a foaf:Group and a foaf:Agent.

In-domain-of and In-range-of
The in-domain-of and in-range-of sections list the properties, defined in some external ontologies, that can be used to describe that subject concept. So most of the properties that I used to describe the Zitgist business above should appear in this list (except if the ontology hasn’t yet been linked to UMBEL; but a dozen are already so as shown in Appendix A of the main technical document).

More General and Specific Subject Concepts

The More General Subject Concepts and the More Specific Subject Concepts sections list the super-concepts and the sub-concepts of the current subject concept (sc:Business in that case). So, we can use UMBEL to describe an even more specific kind of business, for example: an Airline Company. Or we can use UMBEL to describe a more general kind of business: a Commercial Organization.

Finally this Detailed Report Web Service helps people to put a given subject concept into context: how it is related to external ontologies classes; how we can use properties to describe individual of these concepts; how is it related to other subject concepts? It is the tool to answer these questions.

Conclusion

In this blog post we saw how external ontologies classes can be linked to UMBEL to explode their domain: so to enhance their expressiveness. Additionally we saw how to use UMBEL web services to analyze a subject concept and to see its relations with other subject concepts, external classes and properties.

However this is just the beginning of our exploration of UMBEL. Many things are waiting for us at the corner. I am starting to write a series of blog posts that will show you different uses and characteristics of UMBEL. All of them will be explained using real world use cases and challenges. We will see how named entities are related to UMBEL subject concepts. We will see how named entities data sources such as Yago and the John Peel Sessions have been linked to UMBEL. We will see how the UMBEL Vocabulary can help people to describe subject relationship between: a RDFS class that can be linked to a subject concept (using umbel:isAligned and owl:equivalentClass); a named entity to a subject concept (using umbel:isAbout and umbel:linksEntity); and a named entity to another named entity (using umbel:isLike and owl:sameAs).

As you can notice, this is just the beginning. In meantime you can read the technical documentation to have a better understanding of UMBEL. And additionally you can read all the volumes that have been written to explain UMBEL’s evolution and the steps that lead to the creation of this of this first public release of the ontology.

Finally, you can now start using UMBEL in your own applications. I would suggest you to revisit the UMBEL web services by reading my previous blog post: Exploding the Domain: UMBEL Web Services by Zitgist. Additionally I would suggest you to try to dereference subject concepts URIs such as: http://umbel.org/ns/sc/Project and http://umbel.org/ns/sc/Organization. All UMBEL Vocabulary’s classes and properties are dereferencable. All UMBEL named entities are also dereferencable along with all subject and abstract concepts.

Enjoy!

Semantic Web, Bibliographic Ontology

The Bibliographic Ontology 1.0

After months of development and nearly 1000 messages on the mailing list exchanged between 83 participants, the first version of The Bibliographic Ontology has just been published.

This is an important milestone for this project. It has been postponed weeks after weeks to make sure that it was expressive enough to handle all kind of scenarios for all kind of bibliographic projects. We finally reached a consensus and published the first version of this ontology.

I am quite pleased to release it after nearly one year of development. We have a solid basis that can easily be extended to cope with more specialized bibliographic needs. We already know some projects (such as Zotero; thanks Connie) that are planning to use BIBO to describe things related to documents and collection of documents in RDF.

Ontology Resources

Many resources exist to help people to use this ontology to describe bibliographic things.

  • Ontology documentation – is the human readable documentation of the ontology.
  • Ontology description – is the RDF+N3 description of the ontology. (note: all URIs are dereferencable)
  • Mailing list – is the place where people ask questions about how to use the ontology; where people suggest extensions to the ontology; and where people report potential issues.
  • Wiki – is the place where to archive references, write examples and write other stuff related to the ontology.
    • Examples – It is the place where to write BIBO examples.
  • Google Code Repository – is the place where to download the latest version of the working draft of the ontology. Additionally, people can download tools related to the ontology.

Conclusion

I would like to thank everybody that participated to the mailing list and the wiki. Many people put much time and thinking into this ontology, and this release won’t have been possible without their professional work, time and thinking. This is a really complex domain and countless hours have been spent on this project. It is not an end; it is just the beginning.

Please send any questions, comments, suggest and report issues on the mailing list.

I would like to personally thanks Bruce, Yves, Patrick, Connie, Elena, Mark, (I am missing others, please forgive me), and all others for making this happen.