- The Universal Core (UCore) is a central element of the National Information Sharing Strategy that is supported by multiple U.S. Federal Government Departments, by the intelligence community, and by a number of other national and international institutions. The goal of the UCore initiative is to foster information sharing by means of an XML schema providing consensus representations for four groups of universally understood terms under the headings who, what, when, and where. We here describe a project to create an ontology-based supporting layer for UCore, entitled 'Universal Core Semantic Layer' (UCore SL), and describe how UCore SL can be applied to further UCore's information sharing goals.
THE UNIVERSAL CORE
The Universal Core (UCore) [
The prime focus of the UCore initiative is messaging. UCore is designed to promote information sharing across multiple message domains by means of a simple XML message format built on a taxonomical structure comprising four groups of terms under the headings who, what, when, and where. Table 1, below, represents the taxonomy as released in UCore Version 2.0, which is the version upon which we focus in what follows. Table 2 represents the relations contained within the UCore 2.0 xsd:schema.
The UCore strategy is to require message-creators to construct for each message a digest, a summary built out of a restricted vocabulary of UCore terms, and to link elements from the message payload to this digest. Developers of information systems are encouraged to use these terms wherever practical in order to realize the goal of facilitating automated sharing of information within and across agencies. To reap maximal benefit from its messaging resources, participants in the UCore initiative offer validation processes and tools intended to promote machine understanding of message content, thereby enabling multiple different types of information retrieval, reasoning and consistency checking.
The UCore taxonomy consists of terms (such as ‘Person’
or ‘Organization’) which are universally understood in the
sense that they require no domain-specific expertise for their
understanding. The taxonomy can thereby be shared by many
different types of users, and thus it provides the opportunity
for interoperability over many different sorts of
domainspecific exchanges. As M. Daconta expresses it:
if I have a UCore-wrapped National Information Exchange
Model [NIEM] message from Immigration and Customs
Enforcement about illegal immigrants wounded during
criminal activity and I have a UCore-wrapped Health and
Human Service Department message on visitors to emergency
rooms, I have enabled immediate cross-domain search. …
UCore is a process of extracting cross-domain commonality
from your message flows, thereby massively broadening the
possible adoption and use of your shared information. In
information sharing, adoption by consumers is the key value
metric. [
The UCore 2.0 taxonomy in its current form is well adapted to realizing this strategy of information sharing on the basis of universally understood terms. UCore 2.0 as a whole, however, still has a number of problems, including a mismatch between this taxonomy and UCore’s larger XML schema. The latter includes a number of elements that are not represented in the taxonomy, including spatial and temporal terms:
GeoLocation: A physical location with coordinates, or a simple geospatial region; TimeInterval: An interval in time, defined by two instants in time.
Since these elements do not have a corresponding representation in the taxonomy, their intended semantics remain implicit, and no straightforward way exists to link them to, say, spatio-temporal ontologies.
II.
STRATEGY
UCore is designed not only to support messaging and the retrieval and analysis of message content. It is also built in such a way as to support interoperability of information systems of a variety of different types. The strategy is to have UCore serve as the consensus starting point for the construction of successive layers of more inclusive artifacts, uc:LawEnforcementEvent uc:MigrationEvent uc:MilitaryEvent uc:NaturalEvent uc:ObservationEvent uc:PlannedEvent uc:PoliticalEvent uc:PublicHealthEvent uc:SecurityEvent uc:SocialEvent uc:TerroristEvent uc:TransportationEvent creating a growing terminology framework within which there can be threaded interoperability corridors tailored to the needs of specialist groups of users.
Against this background, the Army Net-Centric Data Strategy Center of Excellence is supporting experiments to use UCore as the basis for fostering the interoperability of information artifacts created by Communities of Interest (COIs) in the Command and Control (C2) and other domains. The idea is that such COIs will create new vocabularies tailored to meet their unique requirements and thus go beyond the narrow set of UCore terms. By providing an evolving resource of common terms UCore will serve as a central hub designed to maintain a joint community perspective. The long-term goal is that these common terms will create a common reference platform allowing data from diverse COIs to be understood by systems across the DoD and IC. This approach is also designed to allow a level of information sharing between unanticipated users and systems and to reduce the time and cost to implement information sharing across the DoD and IC enterprise, while allowing COIs to focus on their community specific needs.
To achieve these ends, UCore will need to accommodate new requirements from its partner agencies, while at the same time remaining faithful to its key principle of providing a small set of essential terms and relations. This set will however need to be expanded in order to include those universally understandable terms (such as ‘weapon’) not so far included. UCore has accordingly established a Configuration Control Board (CCB), whose role is to manage change in such a way that successive UCore versions remain useable throughout the change lifecycle.
III.
THE OBO FOUNDRY AND BASIC FORMAL ONTOLOGY
The idea of creating consistent extensions on the basis of a
common core in order to serve interoperability has been
thoroughly explored in the biomedical domain, where the
Gene Ontology (GO) was established already in 1998 [
In 2006, accordingly, the Open Biomedical Ontologies
(OBO) Foundry [
UNIVERSAL CORE SEMANTIC LAYER
We describe in what follows an initiative on the part of the
Army Net-Centric Data Strategy (ANCDS) [
UCore SL is designed to work behind the scenes in UCore 2.0 application environments as a logical supplement to the UCore messaging standard. Where UCore 2.0 is based on the XML format, in which definitions are logically unarticulated and thus logically based merging of content is not allowed, UCore SL employs the W3C’s OWL DL web ontology language, which allows logically articulated definitions to be formulated in such a way as to support such merging. UCore SL offers the entirety of the content UCore 2.0, both taxonomy and relations, in a form which satisfies the needs of users with a need for enhanced logical resources. It provides for logical decomposition of terms and definitions, the ability to reason logically on the basis of the content of these definitions, and thereby also enhanced support for the creation of consistent extension modules. UCore SL is being used as a tool for validation of UCore itself and for the generation of proposals for changes and additions both to UCore 2.0 and to its extensions. It also provides accessibility of UCore message content to W3C-standard OWL-DL technology.
Where UCore 2.0 provides for syntactic interoperability through its XML framework and controlled vocabulary, UCore SL offers a logically organized vocabulary of terms, relations and definitions which can serve the semantic interoperability of UCore message content.
UCore SL is already helping to provide semantic
interoperability in the results of work sponsored by the
ANCDS COE on Biometrics and C2 Ontologies carried out
by NCOR researchers in Buffalo. We are currently evaluating
the ability of UCore SL to provide more powerful reasoning
and message-checking capabilities as compared with UCore
2.0 without the added logical support. We and others are also
testing the capacities of UCore SL to provide facilities for
enhanced data sharing by helping to ensure that extension
modules created by different domains or COIs, for example
within the C2 framework [
The UCore SL Taxonomy (version 1.0) consists of 144 terms organized into an is-a (subclass) hierarchy, of which, following UCore 2.0, the top two terms are sl:Entity and sl:Event (see table below), corresponding roughly to the continuant and occurrent terms standardly used in upper-level ontologies such as BFO. The UCore SL taxonomy comprehends the entirety of the UCore 2.0 taxonomy in the sense that each one of the 55 terms in the UCore 2.0 taxonomy is mapped to a corresponding UCore SL term. As a result, it is possible to translate UCore 2.0 into UCore SL in order to take advantage of the latter’s enhanced logical resources . As UCore itself is expanded, additional resources will be added to UCore SL in order to ensure that this translatability is preserved.
UCore SL contains 16 relations, with definitions relying on
those provided in BFO [
The UCore 2.0 definitions are derived primarily from the Concise Oxford English Dictionary (OED), which, while helpful to human users, unfortunately only goes part of the way to specifying the intended meaning of the terms in a fashion useful to computers. A further problem with this approach is that there are cases where the provided definition is not in agreement with UCore’s own is-a hierarchy. An example is uc:Animal:
A non-human organism which feeds on organic matter, has specialized sense organs and nervous system, and is able to move about and to respond rapidly to stimuli. (Derived from OED)
Given that uc:Person is a subclass of uc:Animal, this definition entails that a uc:Person is a non-human organism. This problem has now been corrected through UCore’s change management process by removing ‘non-human’ from the definition of ‘animal’, but further problems remain. (For example Alert Event is treated by UCore 2.0 is a sibling, rather than as a child, of Communication Event; Weather Event, similarly, is treated as sibling rather than as child of Natural Event.
Other examples of UCore 2.0 definitions are: · · · · · · uc:GroupOfPersons =def A number of people located, gathered, or classed together. (Derived from OED) uc:Organization =def An organized body of people with a particular purpose, e.g. a business or government department. (Verbatim from OED) uc:PoliticalEntity =def An organized governing body with political responsibility in a given geographic region. (Derived from OED) The definition of ‘Organization’ does not make it clear whether or not organizations are groups of persons. The definition of ‘PoliticalEntity’ suggests that it should be a subclass of ‘Organization’, but this is not reflected in the UCore 2.0 taxonomy.
UCore SL, in contrast, rigorously utilizes the structure of the taxonomy in the formulation of its definitions. Every UCore SL term is defined in terms of necessary and sufficient conditions following the Aristotelian schema, which defines each child term ‘A’ in terms of its immediate parent ‘B’ together with the differentia ‘C’ which determines what it is about the B’s which makes them A’s (as in: a human =def. an animal that is rational). Examples from UCore SL are: sl:Government =def. An Organization with political responsibility for governing in a specified GeospatialRegion. sl:Organization =def. An Agent that has (1) members which are Agents, (2) one or more Objectives, and (3) MemberRoles (and other AffiliateRoles) which are realized in the pursuit of the Objective or Objectives sl:GroupOfPersons =def. A Group that includes only Persons. The fact that sl:Government is a subclass of sl:Organization is reflected in both the definition and the taxonomy (see table 3). In UCore SL it is possible to state not merely that sl:Organization and sl:GroupOfPersons are distinct, but also that they share no instances in common, since UCore SL includes explicit disjointness axioms.
VI.
C2 Core
C2 Core, a DoD-level initiative pursuing C2 data interoperability, is exploring a combined top-down/bottom-up approach, which both extends semantics down from UCore 2.0 while also addressing the bottom-up requirements for information exchange brought by specific user groups. The NCOR team is achieving logical consistency through a topdown extension of UCore 2.0 terms, logically defined using the resources of UCore SL, and applying the result to create a C2 conceptual data model called ‘C2 Core’. The latter currently contains over 120 high-frequency terms that define the C2 domain. These terms pertain to situational awareness, structuring a military organization, planning and assigning tasks, decision making, and assessing progress.
Examples of potential targets for extensions of the existing C2 Core include sub-domains such as Strike, Unit Readiness, Planning and Operations, and the Military Decision Making Process (MDMP). Experience in creating UCore SL has yielded a proven process for creating such extensions which results in definitions which are optimized for use both by humans (for teaching and doctrine writing) as well as use by computers (in validation and reasoning).
Using UCore SL to Support Reasoning with UCore Messages
As summarized in [
We are working on a method to quantify the quality of these mappings and the ontologies in such a way that we can demonstrate that one ontology is to be preferred over another, or that one mapping to an ontology is to be preferred over another mapping. By using such quantified measures, we can engineer an evolutionary improvement of ontology resources, which can be used across the entire domain of messaging in areas such as C2, where tight integration of messages deriving from disparate sources is required. UCore SL as Basis for a Cyberwarfare Operations Ontology
While standard military operations doctrine is thoroughly
documented in Joint Publications (JPs), Field Manuals (FMs),
and other reference materials, this is not the case for military
operations in cyberspace. Now, however, with the increasing
importance of cyberwarfare, there is a need for standardized
terminological resources which can serve as the basis for
formulation of sound doctrine and also be applied to other
purposes such as the development of international law
pertaining to cyberwarfare. Doctrine and law can be written
only if experts agree on the semantics of the domain [
As part of the design process, UCore SL has a built-in
crosswalk between UCore SL and BFO. In an effort to make
UCore as widely applicable as possible, additional crosswalks
to the other major upper-level ontologies DOLCE [
UCore 2.0 andJC3IEDM
The Joint Consultation, Command and Control Information
Exchange Data Model (JC3IEDM) is a model that aims to
enable international interoperability of C2 information
systems at all levels in order to support multinational
(including NATO) combined and joint operations and the
advancement of digitization in the international arena [
CONCLUSION
UCore SL, an ontology-based supporting layer for UCore, is designed to work behind the scenes in UCore 2.0 application environments as a logical supplement to the UCore messaging standard. UCore SL builds upon previous work in the biomedical domain on creating consistent extensions on the basis of a common core ontology in order to serve interoperability. UCore SL provides the logical resources for the UCore initiative to do this work.
UCore SL is currently in the beta phase of development, with several current and potential users who are testing it in their application environments and providing valuable feedback in order to help improve future versions of UCoreSL. In order to demonstrate the true value of UCore SL it is necessary to develop a significant user community around UCore SL, one where multiple extension ontologies are subjected to rigorous logical analysis and testing, linked together in computable ways, and used to annotate large quantities of data. In this way it will be possible to show how UCore SL’s added logical resources can meaningfully advance UCore’s information sharing goals.
Thanks are due to Paul Birkel, Brian Haugh, William Mandrick, Randall Dipert, Leo Obrst, Ron Rudnicki, and especially to Deborah Nichols, for valuable contributions to the development of UCore SL.