A Program for Building a State of the Art Enterprise Ontology: Report on Progress Chris Partridge1, Milena Stefanova2 1The BORO Program, partridge@BOROProgram.org. 2LADSEB CNR, Italy, stefanova@ladseb.pd.cnr.it. Abstract: This paper is a report on progress of the CEO project whose goal is to build a state of the art enterprise ontology. The project is currently at the stage of har- vesting insights from the best existing enterprise ontologies. The goal of this stage is to synthesising from these a Base Enterprise Ontology. This will then be used as the foundation for the construction of the ‘industrial strength’ Core En- terprise Ontology (CEO). The synthesis is intended to build upon the strengths and eliminating – as far as possible – the weaknesses from the selected ontolo- gies. Among other things, this paper describes one of the main achievements of this work to date: the development of the notion of a person (entities that can ac- quire rights and obligations) enabling the integration of a number of lower level concepts. In addition, it identifies some of the common ‘mistakes’ in current en- terprise ontologies – and proposes solutions. 1. INTRODUCTION This paper reports on the initial results from an ongoing project – the CEO (Core Enterprise Ontology) project that is part of the BORO Program [BORO]. The CEO project aims to build an ‘industrial strength’ enterprise ontology, that will be suitable as a basis for facilitating, among other things, the semantic interoperability of enterprises’ operational systems. This initial stage of the project involves a collaboration with the European IKF (Intelligent Knowledge Fusion) [EUREKA] project. This European IKF project will ultimately develop a Distributed Infrastructure and Services Sys- tem (IKF Framework) with appropriate toolkits and techniques for supporting -- 1 of 9 -- 2 C. Partridge, M Stefanova knowledge management activities. The project is planned to take 3.5 years (it started in April 2000) and has participants in Italy, UK, Portugal, Spain, Hun- gary and Rumania. The IKF project aims to develop two kinds of ontology: – a Reference Ontology composed of a Top Level Ontology and several Core Ontologies [B1997]. The top level ontology contains primitive general concepts to be extended by lower-level ontologies. The core ontologies span the gap between various application domains and the top level ontology. – Domain Ontologies. The vertical applications will build ontologies for their specific domains. For example, there is an IKF/IF-LEX project that is building a domain ontology for bank supervision regulations, fo- cusing on money laundering. 2. SYNTHESIS WORK PLAN The first stage of the CEO project is a synthesis of the best existing enter- prise ontologies. The scope of this stage is large – and so the work has been divided into more manageable chunks. As [B1997] states, a core ontology contains “the categories that define what a field is about.” A first rough intuitive guess of what these categories might be has proved not only a useful basis for segmenting the work but also helped to clarify the focus on the important aspects for the CEO. Our guess of what the categories might be is: – parties (persons) which may enter in – transactions (composed of agreements and their associated activities), involving – assets. A review of existing ontologies was made and a sample of the best selected on the basis of: – the relevance of their content to the Core Enterprise categories, and – the clarity of their characterisation of the intended interpretations of this content [G1997], [G1993] & [P1996]. This gave us the following list: – TOronto Virtual Enterprise - TOVE [F1993], [F1996] & [TOVE], – AIAI’s Enterprise Ontology - EO [EO], [U1997] & [U1998], – Cycorp’s Cyc® Knowledge Base - CYC [CYC], – W.H. Inmon’s Data Model Resource Book - DMRB [I1997] & [H1997]. The work proceeds by analysing one category in one ontology at a time, and then re-interpreting the previous results in the light of any new insights. -- 2 of 9 -- Synthesising an Industrial Strength Enterprise Ontology 3 Initially, the work focuses on individual ontologies but as it proceeds there is enough information to start undertaking comparisons between ontologies. The final analysis will encompass analyses of both the individual ontologies and comparisons between them. In each of the ontologies, the concepts and relations relating to the cate- gory being considered are examined for the clearness and uniformity of their descriptions and formalisations. Further, each concept is analysed for its cov- erage and extendibility in cases where the coverage is not complete. Relations between concepts that are not explicitly described, but clearly exist, are identi- fied as well. In addition, for the sake of a clear interpretation, we have found it necessary to consider the top concepts (whether or not they are explicitly de- scribed). An important part of the analysis is testing each concept and its relations against a number of standard examples and more specialized concepts. Fur- ther, a check is made against a number of standard difficult cases. Both these checks help to identify weaknesses in the coverage of the ontologies. A key concern in the analysis is to understand how the various concepts interlink with one another, to better understand the unifying structure of the enterprise field. At various stages during the analysis an interim ontology is synthesised from the strengths found in the analysis, in such a way as to eliminate the known weaknesses – and itself analysed. In the final synthesis, all the catego- ries in all the ontologies are combined into a base CEO ontology. At this time, our work is concluding the analysis of the Parties (Persons) category for the EO and TOVE ontologies – and early drafts of synthesised ontologies are being reviewed. There is still substantial work that needs to be done in determining the precise relations between concepts, such as LEGAL ENTITY and OWNERSHIP within the EO. 3. INITIAL FINDINGS Both the ontologies have many important insights and provide much useful material. However, our most general findings, at this stage, are that none of the ontologies: – adequately meet our criteria of clear characterisation, or – really share a common view of what an organisation is. These findings, taken together mean that the creation of the synthesised base CEO ontology cannot just be a simple merging of the common elements of the selected ontologies. We now illustrate these findings with examples and show how we synthe- sised a resolution to some of them. -- 3 of 9 -- 4 C. Partridge, M Stefanova 3.1 Clear Characterisation When the characterisation is unclear, it is difficult to work out the intended interpretation – in the worst case, impossible to decide between competing interpretations. There are many different ways in which the characterisation can be unclear – as we describe below. A clear overview of the structure helps understanding. Neither TOVE nor EO had one, so we developed graphical representations based upon ER dia- grams. Figures 1 & 2 provide simplified versions of these. Both TOVE and EO make use of a number of top concepts. A top ontol- ogy – or top concepts – can provide a useful structure that segments the en- terprise and other domains into general categories that help in defining and the use of domain concepts and relations. However, if this is not done properly it can have the opposite effect. Some of the problems we encountered with the top concepts and the do- main analysis in the selected ontologies are: – Insufficient characterisation of the disjointness of top concepts. For example, in the informal EO the relationship between the top con- cepts ENTITY, and ROLE is not clear – in particular, whether ROLES Organisation Unit Person Legal Entity Potential Actor works for manages Partnership Corporation partner of Figure 1. Simplified EO overview Organisation Individual- Agent Group- Agent Organisation- Agent Organisation- Unit org-unit member Organisation- Position position unit authority Figure 2. Simplified TOVE overview -- 4 of 9 -- Synthesising an Industrial Strength Enterprise Ontology 5 can be ENTITIES or not, and so whether they can enter into RELA- TIONSHIPS. – The same lack of care in characterising disjointness (and overlapping) exists at the domain level in both TOVE and EO. We found this can make it impossible to definitively determine the intended interpreta- tion. For example, in TOVE the formalisation allows an ORGANI- SATION-UNIT to be an ORGANISATION – though this seems counter-intuitive, and probably not what the authors intended. – Not applying top concepts. TOVE states that a fluent is "a [type of] predicate or function whose value may change with time". But it does not identify which predicates in its ontology are fluents – leaving this to the readers, who have to make their own judgements. Supplying such information would have helped not only the users of the ontol- ogy but also its creators and designers. For example, the TOVE's creators end up (probably unintentionally) having to regard OR- GANISATION as a fluent – when in the normal (commonsense) use of the concept it is not. – Messy formalization trajectories. EO formalizes its concepts in logi- cal systems (Ontolingua and KIF), which rely on their own (different) top concepts. An attempt for a clear formalisation trajectory has been made [U1997], but unfortunately this does not match very well with the informal specification. For example, in the informal EO it is stated that each RELATIONSHIP is also an ENTITY, but is not defined as such in the formalization. Furthermore some RELATIONSHIPS are defined in the formalization as classes and others are defined as rela- tions without explaining what the motivations for these choices are (e.g., SALE is a RELATIONSHIP formalized as a class, HAVE- CAPABILITY is a RELATIONSHIP formalized as a relation). This becomes a more serious problem if the formalisation is meant to be taken as the more accurate version. – Failing to use general concepts to achieve uniformity. Both TOVE and EO fail to use top concepts to describe in a uniform way core re- lations and concepts. This hampers understanding. Typical examples are the part-of relation, used in describing the decomposition of or- ganizations into smaller units, and the relation, which shows the dif- ferent ways for participation in organizations. For example, TOVE introduces two kinds of part-of relations: org-unit (between OR- GANISATION and ORGANISATION-UNIT), and unit (between two ORGANISATION-UNITs). These relations express ORGANISATION and ORGANISATION-UNIT decompositions, but are not explicitly unified under a common relation. In the EO several ways of partici- pating in a company are considered, as a partner (partner_of relation -- 5 of 9 -- 6 C. Partridge, M Stefanova between PERSON and PARTNERSHIP), as an employee (works_for relation between PERSON and OU), as a shareholder in a corporation (only in the informal EO specification, Uschold, et al, 1997). These ways of participation are not unified in the EO. – Insufficient analysis. As an example consider the EO concepts of OWNERSHIP and SHAREHOLDING (Uschold, et al, 1997), which are formally unrelated, while SHAREHOLDING as evident from its informal and formal, definitions represents the ownership relation be- tween a CORPORATION and its owners. 3.2 Common view of an organization TOVE and EO do not share a common view of an organisation. Even a cursory glance at Figures 1 & 2 (which give a broad picture) reveals there are significant differences. There are many examples in both TOVE and EO of how a better analysis would have led to more similar views: – Insufficient analysis. In TOVE, for example, it seems that an OR- GANISATION is not an AGENT, but has AGENTS as members. Yet as EO recognises there are many examples of organisations (such as the EU or NATO), which have other organisations as members. – Missing Links. In the EO, the relation between the concepts OU and LEGAL ENTITY is unclear. All that we are told is that a LEGAL EN- TITY "may correspond to a single OU" (Uschold, et al, 1997). No fur- ther analysis (informal or formal) of the link between these two con- cepts is given. – Implicit context dependencies. In the EO, the concept LEGAL EN- TITY, is not well thought out – having several (informally inconsistent) descriptions. It seems that the intended meaning actually depends on a particular jurisdiction (in this case on the current UK jurisdiction) – though it is not clear that the authors recognise this. This dependence is inappropriate in the modern global economy – and it raises potential problems should the UK jurisdiction change. For example, the LEGAL ENTITY concept would no longer be the "union of PERSON, CORPO- RATION, and PARTNERSHIP". 3.3 Unifying the Core Concepts: Person A vital missing element from both the ontologies is a unifying core cate- gory. Part of the synthesis work is to try and incorporate these in preparation for a synthesised common view. -- 6 of 9 -- Synthesising an Industrial Strength Enterprise Ontology 7 So we introduced the unifying category PERSON (PARTY), which can be a NATURAL PERSON or SOCIALLY CONSTRUCTED PERSON (SO- CIAL PERSON in short). This acts as the catalyst for transforming the on- tologies into ones with similar characteristics. The natural next step (which we plan to undertake soon) is to merge them into a single synthesised ontology. The result of introducing PERSON into the EO ontology is shown in Fig- ure. 3. A comparison of this with Figure 1 shows how PERSON has unified the taxonomy. To give the reader some idea of how this transformation was effected, we describe the steps we went through. The EO concepts PERSON (human be- ing) and OU are renamed NATURAL PERSON and SOCIAL PERSON. These are then generalised into the concept PERSON. LEGAL ENTITY is taken completely out and substituted with the context independent notion of LEGALLY CONSTRUCTED PERSON (LEGAL PERSON in short) – a subtype of SOCIAL PERSON. Note that LEGAL PERSON is not the same concept as the EO LEGAL ENTITY, since it is intended to represent parties, which are constructed ac- cording to a legal jurisdiction, but not necessarily recognised by it as legal per- sons (in EO terms, LEGAL ENTITYs). For example, in the UK a partnership is Legal Person participation Social- Person Person Natural- Person person-part works for Legal Partnership Legal Corporation partner-of Figure 3. EO transformation -- 7 of 9 -- 8 C. Partridge, M Stefanova not legally recognized as a person (it cannot sign contracts in its name) but it is a LEGALLY CONSTRUCTED PERSON, because there are legal constitution rules for partnerships. Finally the two participation relations, partner_of and works_for are consolidated under a general participation relation, and the relation manages is renamed into person-part (which is a particular kind of part_of relation). The result of introducing PERSON into the TOVE ontology is shown in Figure 4. As before, a comparison of this with Figure 1 shows how PERSON has unified the taxonomy. The transformation steps between Figure 2 and Figure 4 are similar in many respects to those between Figures 1 and 2. 4. CONCLUSION Even at this early stage our work has revealed both the need for a substan- tial improvement in enterprise ontologies to bring them up to ‘industrial strength’ and a route for doing so. Hopefully, our future work will go some way towards realising this across the whole enterprise ontology. Organisation- Position authority member- participation Social- Person Person Natural- Person person-part occupies Figure 4. TOVE transformation -- 8 of 9 -- Synthesising an Industrial Strength Enterprise Ontology 9 5. ACKNOWLEDGEMENTS We would like to thank to the BORO Program and IKF Project for helping to make this research possible. Furthermore we would like to thank to Ales- sandro Oltramale, Claudio Masolo, and Nicola Guarino for the numerous fruit- ful discussions we had on topics related to ontologies and organisations. 6. REFERENCES [BORO], http://www.BOROProgram.org [B1997] Breuker J, Valente A., Winkels R. 1997, Legal Ontologies: A Functional View in P.R.S. Visser and R.G.F. Winkels, Proceedings of the First International Workshop on Legal Ontologies, [CYC] http://www.cyc.com/publications.html [EO] http:// www.aiai.ed.ac.uk /project/ enterprise/enterprise/ ontology.html [EUREKA] http://www3.eureka.be/Home/projectdb/PrjFormFrame.asp?pr_id=2235 [F1993]Fox, M.S., Chionglo, J., Fadel, F., 1993, A Common-Sense Model of the Enterprise, Proceedings of the Industrial Engineering Research Conference. [F1996] Fox, M.S., Barbuceanu, M., and Gruninger, M., 1996, An Organisation Ontology for Enterprise Modelling: Preliminary Concepts for Linking Structure and Behaviour, Computers in Industry, Vol. 29, pp. 123-134. [G1993] Gruber, T., 1993, Toward Principles for the Design of Ontologies Used for Knowl- edge Sharing, in Formal Ontology in Conceptual Analysis and Knowledge Representa- tion, Nicola Guarino and Roberto Poli Eds. [G1997] Guarino, N., 1997, Semantic Matching: Formal Ontological Distinctions for Infor- mation Organization, Extraction, and Integration. In M.T. Pazienza (Ed.) Information Extraction: A Multidisciplinary Approach to an Emerging Information Technology. [H1997] Hay David C., 1997, Data Model Patterns: Conventions of Thought, Dorset House. Inmon W.H. 1997, The Data Model Resource Book: A Library of Logical Data and Data Warehouse Models, John Wiley and Sons. [P1996] Partridge, C. 1996, Business Objects: Re-Engineering for Re-Use, Butterworth- Heinemann. [TOVE] http://www.eil.utoronto.ca/tove/ [U1997] Uschold, M., King, M., Moralee, S., and Zorgios, Y. 1997, The Enterprise Ontology, AIAI, The University of Edinburgh, [U1998] Uschold, M., King, M., Moralee, S., and Zorgios, Y. 1998, The Enterprise Ontology, in The Knowledge Engineering Review, Vol. 13, Eds. M. Uschold and A. Tate, -- 9 of 9 --