=Paper=
{{Paper
|id=Vol-2518/paper-SOLEE6
|storemode=property
|title=A Foundational View on Roles in Conceptual Modeling
|pdfUrl=https://ceur-ws.org/Vol-2518/paper-SOLEE6.pdf
|volume=Vol-2518
|authors=Fumiaki Toyoshima
|dblpUrl=https://dblp.org/rec/conf/jowo/Toyoshima19d
}}
==A Foundational View on Roles in Conceptual Modeling==
https://ceur-ws.org/Vol-2518/paper-SOLEE6.pdf
A Foundational View on Roles
in Conceptual Modeling
Fumiaki TOYOSHIMAa,1
a
Graduate School of Advanced Science and Technology, JAIST, Japan
Abstract. Roles remain elusive entities, although they are an integral part of socio-
economic reality. This paper aims to examine roles in conceptual modeling from a
foundational viewpoint. More specifically, we revisit Friedrich Steimann’s well-
known list of features of roles in light of the recently proposed ‘three-facet theory’
of roles that exploits a meta-ontological notion of grounding. We also hint at a
strategy for formalizing an ontological module for generic role representation.
Keywords. role, conceptual modeling, relationship, context, grounding
1. Introduction
The socio-economic world is chock-a-block with roles (e.g., students) and the role
concept is indispensable for rigorous modeling of multifarious social entities. For
instance, it is nowadays fairly popular to model organizations (totally or partially) upon
interrelations among roles in a number of different disciplines, ranging from multiagent
systems [1,2] to enterprise modeling [3] and ontology research [4-6]. A careful analysis
of roles is nonetheless so fraught with difficulties that it is still a controversial topic
whether there is any single definition of role or not [7]. Even if “there is no single kind
of roles, and no unique kind of entities on which roles depend” [8, p. 144], the challenge
lies in providing a general characterization of multiple meanings of roles (see e.g., [9]).
The purpose of this short paper is to present a foundational perspective on roles in
the context of conceptual modeling. Put concretely, we will reconsider Steimann’s [10]
list of features of the role concept that has been intensively discussed in (foundational)
ontology research. Characteristic of our methodology is to leverage Toyoshima’s [11]
recent ‘three-facet theory’ of role, which says with a focus on ontology-driven conceptual
modeling that there are three major interpretations of role in upper ontologies: a role
specification, a role position, and a role potential. The work of the paper will enhance
further development of the three-facet account, thereby contributing to a deeper
understanding of roles from a modeling viewpoint. The rest of the paper is structured as
follows. Section 2 presents an overview of the three-facet theory of role together with a
more detailed explanation of meta-ontology and a meta-ontological notion of
(fact-)grounding than Toyoshima [11] provides. Section 3 examines Steimann’s 15
features of role in terms of the three facets of roles. Section 4 concludes the paper with a
brief discussion on a possible way of designing a general role module.
1
E-mail: toyo.fumming@gmail.com, fumiakit@buffalo.edu. Copyright © 2019 for this paper by its
authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).
2. Three Facets of Roles
2.1. Grounding as a Meta-ontological Tool
Toyoshima [11] adopts a meta-ontological approach to roles. In foundational ontology
research, there is an increasing practical interest in meta-ontology as a second-order
inquiry into ontologies. Among meta-ontological concepts is a truthmaker [12,13]:
something that ‘makes true’ (i.e., bears the ‘truthmaking relation’ towards) a proposition.
The idea of truthmaker or truthmaking has been employed for the last decade to clarify
complex ontological categories and relations. Examples include the formalization of
states (of affairs) as truthmakers for propositions [14] and the conceptualization of
properties, relations, and events in terms of ‘truthmaking patterns’ [15,16].
As a sibling notion of truthmaking, grounding [17-19] serves as a key conceptual
tool in Toyoshima’s [11] theorizing on roles, or especially its most orthodox version
does: grounding as a primitive relation between facts [20,21]. For instance, the fact (say
F1) that a table exists is grounded in the fact (say F2) that some subatomic particles are
arranged table-wise; and informally, F1 holds ‘in virtue of’ F2. The theory of fact-
grounding is usually coupled with the claim that the grounding relation at least entails
explanation (see [19] for controversy over grounding and explanation). In the table
example, F2 grounds, and ipso facto explains F1. Grounding is also so analogous with
causation that one may sometimes call grounding ‘ontological causation’ [22].
Fact-grounding presupposes an ontology of facts. To keep things manageable, we
leave aside the problematic character of facts (see e.g., [23]) and simply say that the term
‘fact’ is typically interpreted either as a true proposition or as a state of affairs. On the
one hand, a proposition is standardly taken to play three major roles:
• The semantic content of a (declarative) sentence. E.g., two sentences “Snow is
white” and “La neige est blanche” express the same proposition that snow is
white.
• The object of various linguistic and cognitive attitudes (‘propositional
attitudes’) including belief, assertion, and denial. E.g., when she sincerely utters
“Snow is white,” Mary bears the believing attitude towards the proposition that
snow is white.
• The truthbearer: the bearer of truth-values (truth and falsehood). E.g., the
proposition that snow is white is true.
On the other hand, a state of affairs is a concrete, non-lingo-cognitive portion of reality,
but with a ‘propositional structure’: e.g., a state of affairs of snow being white [24]. A
fact can be therefore described as something that ‘holds’ in reality in virtue of its
propositional structure, irrespective of whether it is a true proposition or a state of affairs.
We can distinguish two kinds of grounding relations: full and partial grounding [21].
A plurality of facts F1, F2, … fully ground a fact G (symbolization: F1, F2, … ⇒ G) when
F1, F2, … ground G collectively and completely; and a fact F partly grounds a fact G
(symbolization: F → G) when F grounds G singly and partially. Partial grounding can
be naturally defined in terms of full grounding: F → G if and only if there exist F1, F2,
… such that F, F1, F2, … ⇒ G. To illustrate them, let H and I be the fact that Japan is an
eastern Asian country and the fact that Japan has a population of nearly 130 million,
respectively; and let J the fact that Japan is an eastern Asian country with a population
of nearly 130 million. Then, the following claims hold: H → J, I → J, and H, I ⇒ J.
We can also speak of some formal properties of grounding (whether full or partial)
[21]. (i) Irreflexivity: no fact grounds itself. (ii) Transitivity: if a fact F1 grounds a fact
F2, which in turn grounds a fact F3, then F1 grounds F3. From (i) and (ii) follow
straightforwardly the asymmetricity of grounding: if a fact F1 grounds a fact F2, then it
is not the case that F2 grounds F1. To simplify the matter, we set aside a highly debatable
topic of whether grounding is, in some sense, ‘well-founded’: whether it has no infinite
descending chains or not (see e.g., [25] for details). Note that, unlike grounding, the
truthmaking relation fails to preserve the property of chaining [21].
While examining some preceding accounts of roles, Toyoshima [11] hypothesizes
that different theories of role might depend on different ‘role choices’ made by the
theories: choices as to which is most fundamental among the ‘three facets’ of role (which
he calls the ‘role triad’), or its three main ontological interpretations, namely a role
specification, a role position, and a role potential. To paraphrase it using fact-grounding
simply, we introduce the notation ‘< >’ to refer to facts: e.g., .
We also accept the widespread recognition that a role is a ‘playable property’: a
property to be played by something (‘player’). To be precise about the alleged playability
of roles, we introduce Bird’s [26] distinction between ‘predicatory properties’ and ‘ontic
properties’. Predicatory properties are properties that are defined by almost any predicate
(e.g., “This apple is green or not green”). The predicatory usage of the term ‘property’
is an ontologically uncommitted, mere façon de parler: e.g., the property of being green
or not green. Ontic properties are, by contrast, properties with a distinctive ontological
role such as the property of being negative charged (which is vital in physics and
chemistry). In this paper we speak of playing a role in the predicatory (but non-ontic)
sense of the phrase. 2 The role-playing can be illustrated with Mary’s studentness and
fact-grounding as follows:
⇒ (1)
Construed in light of fact-grounding, the core of Toyoshima’s [11] argument is that three
different role choices lead to three different facts each of which fully grounds and, by the transitivity of (full) grounding, .
2.2. Role Specification
One approach to Mary’s studentness focuses on the deontic or normative dimension of
her student role. Mary must gain admission to the ABC college in order to become an
ABC-college student. To enjoy a full-time student status, she needs to register for a
certain number of credit hours per semester. She is also required to defend her
dissertation to obtain a doctoral degree from the ABC college. Mary’s studentness is thus
explicable in terms of the satisfaction of the constraints or conditions that are, so to speak,
‘designated’ by her student role.
This observation would lead to an analogy between a role and a specification. The
ontological nature of a specification remains obscure, but Turner [28] maintains
insightfully that a specification is something that has “correctness jurisdiction over an
artefact” [28, p. 147]. By ‘correctness jurisdiction’ he means that the specification places
2
For instance, our predicatory talk of role-playing must be sharply distinguished from the has_role (ontic,
arguably) relation that is endorsed by an upper ontology Basic Formal Ontology (BFO) [27].
“empirical demands on the physical device” [28, p. 144]. If an artifact is not built to a
certain specification, the artifact is defective with respect to that specification. Duncan
[29] illustrates this point as follows: “For example, if I build a physical implementation
of a stack and the device does not allow me to add and remove items from the top of the
device, my device is defective relative to the specification of a stack” [29, pp. 16-17].
Quite importantly, Turner considers specifications as intentional: “Our intentional stance
determines what we take to be the specification: something is a specification if we give
it normal force over the construction of an artefact” [28, p. 147].
A role specification refers to a role that is understood by analogy with a specification
and role-playing is interpreted as meeting a role specification. This amounts to the
following full grounding:
⇒ (2)
On this specification view of role, a player is to its role what an artifact is to its
specification. In this respect, roles and artifacts are closely linked from a modeling
perspective [30]. In the U.S., for instance, an aircraft has to meet the strict specification
laid down by the Federal Aviation Administration (FAA). This means that an aircraft-
like aggregate of mechanical parts is not an aircraft unless it is constructed exactly to the
FAA specification. Likewise, the ABC college has drawn up intentionally its ‘student
role specification’ (e.g., admission requirements), and Mary fails to be an ABC-college
student unless she satisfies the ABC-student role specification.
2.3. Role Position
Another possibility for understanding Mary’s studentness is based on the kind of
situation in which Mary plays a student role. As an ABC-college student, Mary can use
various facilities and enjoy educational opportunities (e.g., taking classes). Mary’s
studenteness may then consist in the fact that she locates herself in a specific ‘sphere’ or
‘position’ where she can do something role-related.
A role as conceptualized this way is analogous with a relative place [31]. Given the
Newtonian conception of absolute space, both absolute places and relative places persist
and may be occupied by various (material) objects at various times. Unlike absolute
places (which are parts of absolute space that are independent of objects), relative places
stand in fixed spatial relations with one or more objects (reference objects [31]).
Examples include places in and around a ship whose reference object is the ship.
A role position means a role that is figured out by analogy to a relative place and
role-playing is construed as occupying a role position. In other words:
⇒ (3)
Seen from this positional perspective, roles stand in fixed ‘conceptual’ relations towards
one or more entities, which may be sometimes called ‘context’ in the relevant literature
[8,32]. In playing an ABC-student role, for example, Mary occupies the student role
position that exists relative to the ABC college.
2.4. Role Potential
Yet another interpretation of Mary’s studentness is modelled upon the ability of Mary to
do something role-associated (which is sometimes informally called ‘circumstantial
possibility’). Since she is an ABC-college student, Mary can do many things (e.g.,
getting a student discount). She is able to acquire a degree from the ABC college,
whereas non-ABC-college students are not. Mary’s studentness would be explainable in
terms of the potential that she bears in playing a student role.
A role potential designates a role that is thought of as a sort of circumstantial ability
and role-playing is translated as bearing a role potential. That is to say:
⇒ (4)
It is important to remark that, on this construal, a player has only to possess the role-
related ability instead of demonstrating it actually. To remain an ABC-college student,
Mary does not need to use any student discount; it is only necessary that she be able to
do it.
A role potential may be easiest to understand in the role triad because it is intuitively
grasped as a special kind of ability and avoids complications added by analogies with the
complex notions such as a specification (in the case of a role specification) and a relative
place (in the case of a role position). In contrast, a role potential should be treated with
the utmost caution because it could be conflated with other apparently similar but
different entities, viz. dispositions and functions.
3. Steimann’s List of Features of Role
Steimann [10, pp. 86-87] identifies 15 features of roles that appear in the object-oriented
and conceptual modeling literature, adding that “some conflict with others, and hence
that there is no single definition of roles integrating all of them.”3 We will consider each
feature of roles in Steimann’s list in terms of the role triad. Note that we will not delve
into details owing to spatial limitations.
3.1. “A role comes with its own properties and behaviour.”
Although this is a “basic property” of roles according to Steimann, this statement is open
to interpretation because so are the terms therein ‘comes with’ and ‘its own’. On a
charitable construal, the role triad would all have this quality; and this is true of a role
potential most clearly because it is a kind of circumstantial property (ability) that can be
manifested in the player’s behaviors. On the other hand, it is less clear how a role
specification and a role position possess their own properties and behaviors. They may
be said to have this feature in virtue of their intimate connection with some role potential.
3
For readability, we will henceforth cite Steimann [10, pp. 86-87] with no explicit reference to the
literature unless otherwise specified.
3.2. “Roles depend on relationships.”
Steimann says: “a role is meaningful only in the context of a relationship.” This aspect
of role would fit best with a role specification because it comes into being only when it
relates to (precisely: inherits intentionality from) agents. In contrast, a role position
would prefer the notion of context over relationships because it is based on the analogy
of reference objects, which would be well conceptualized as a context (see e.g., [8,32]).
Finally, a role potential has this feature in the sense that the player (e.g., Mary) is in some
relationship (e.g., marriage). Note that the potential conception of role (i.e., a sort of
ability) depends (existentially) on the player rather than relationships.
3.3. “An object may play different roles simultaneously.”
It can be safely admitted that the role triad satisfy this desideratum. At the same time, the
player can meet different role specifications, occupy different role positions, or bear
different role potentials.
3.4. “An object may play the same role several times, simultaneously.”
“This is an equally fundamental finding, a frequent example of which being an employee
holding several employments. (…) each occurrence of the object in a role is associated
with a different state.” This trait of role is clearly observed in the cases of a role
specification and a role potential. It varies with the situation how well the player meets
a role specification; and a role performance ability can be manifested differently in
different scenarios. By comparison, we could conceive that the player can occupy a role
position with different degrees, but it is less intuitive what it really means to speak of the
extent of, e.g., Mary’s occupying a student role position.
3.5. “An object may acquire and abandon roles dynamically.”
It would seem that all of the role triad have this aspect. It is well worth noting however
that talk of the ‘acquisition’ and ‘abandonment’ of roles would match well a role
potential because it conceptualizes a role as a kind of circumstantial ability, i.e.,
something to be acquired or abandoned literally.
3.6. “The sequence in which roles may be acquired and relinquished can be subject to
restrictions.”
“For example, a person can become a teaching assistant only after becoming a student.”
Although it is not hard to see that the role triad would all meet this criterion, the
restriction on role-playing is observed most obviously in the case of a role specification
because it is typically imposed intentionally by some agent. The qualification
requirements of a teaching assistant are provided by the ABC college, for instance.
3.7. “Objects of unrelated types can play the same role.”
Almeida et al. [3, p. 255] illustrate this feature as follows: “For example, both a person
(John) and an organization (the University of Twente) can play the role of customer in
different business relationships.” This property would be concordant with a role
specification and a role position: John and the University of Twente can meet the same
customer role specification and occupy the same customer role position. A role potential
may not satisfy this desideratum straightforwardly, however, because John and the
University of Twente must have different customer role potentials, although those
abilities can be of the same type, i.e., the customer role type.
3.8. “Roles can play roles.”
“This mirrors the condition that an employee (which is a role of a person) can be a project
leader, which is then a role of the employee (but also another role of the person, although
only indirectly).” As was alluded to in Section 3.6, each of the role triad has this property,
and this is the case especially with a role specification.
3.9. “A role can be transferred from one object to another.”
“It may be useful to let a concrete role dropped by one object be picked up by another,
or even to specify the properties of a concrete role without naming a particular role player.
For example, the salary of an open position may be specified independently of the person
that will be employed” (our italicization added). The transferability of roles would mesh
well with a role specification and a role position, which both remain neutral on its player.
On the other hand, a role potential would not ‘migrate’ from player to player, and it
would meet this criterion only in the sense of being inextricably linked with some role
specification and/or some role position.
3.10. “The state of an object can be role-specific.”
“The state of an object may vary depending on the role in which it is being addressed.”
Although it would match each of the role triad, this quality is indicated most clearly by
a role position because it consists in taking role-playing to be located in a special kind of
state or situation.
3.11. “Features of an object can be role-specific.”
“Attributes and behaviour of an object may be overloaded on a by-role basis, i.e.,
different roles may declare the same features, but realize them differently. If an object
plays several of these roles simultaneously, it responds according to the role in which it
is being addressed.” All the role triad would meet this standard; but as we implied in
Section 3.1, role-specific properties and behaviors are shown most vividly by a role
potential.
3.12. “Roles restrict access.”
“When addressed in a certain role, features of the object itself (or of other roles of the
object) remain invisible. This corresponds to an object having different perspectives,
facets, or aspects.” We agree with Almeida at al.’s [3] view that this is an
implementation-oriented feature and omit to discuss it because it is outside the scope of
our foundational investigation into roles in conceptual modeling.
3.13. “Different roles may share structure and behaviour.”
“This usually means that role definitions inherit from each other (…), but sometimes also
that the definitions of roles rely on features of the objects playing them (delegation) (…).”
According to Almeida et al.’s [3, p. 255] illustration: “For example, both graduate
students and undergraduate students have a student number, may register to courses, etc.”
We think that all the role triad would satisfy this desideratum of role nearly equally; but
a role specification might capture this aspect more clearly because it clarifies well how
roles are defined (intentionally).
3.14. “An object and its roles share identity.”
Note that this feature and the next contradict each other. On our three-facet account of
role, a role and its player could possibly have the same identity condition in the case of
a role potential. As said in Section 3.2, a role potential depends existentially on its player.
This means that the potential conception of role (e.g., Mary’s student role) ceases to exist
when its player (e.g., Mary) does, albeit not vice versa. In this regard, a role (potential)
and its player may be said to have ‘temporal identity’ in common.
3.15. “An object and its roles have different identities.”
In contrast, this opposite claim would fit well with a role specification and a role position
because they would continue to exist even when its (possible) player perishes. This is a
noteworthy feature from a modeling standpoint, as Steimann says: “This view (…) is a
tribute to the so-called counting problem. It refers to the situation in which instances
counted in their roles yield a greater number than the same instances counted by the
objects playing the roles. For example, the number of passengers taking a certain means
of transportation in one week may be greater than the number of individual persons
traveling with that means during the same period.” For space reasons our precise three-
facet treatment of the counting problem has to be left for future work; but we point out
that there is a growing consensus that it constitutes a workable solution to introduce qua-
individuals [33,34] (aka role-holders [32]): roughly, new entities constituted of a player
and properties that are relevant to role-playing (e.g., Mary-qua-student).
4. Discussion and Concluding Remarks
In short, we provided a foundational view on roles in conceptual modeling. More
specifically, we revisited Steimann’s [10] list of features in terms of the three-facet
theory [11] of role. Further investigation is clearly warranted into each characteristics of
roles and its relationship with the role triad. We conclude by discussing briefly a possible
strategy for building an ontological module for generic role representation. There is an
increasing demand for an integrated conception of roles, as evidenced by preceding
attempts to elaborate the role data model [35,36]. Our grounding approach to roles might
provide an important clue as to how to ontologize roles. As is indicated by Formulas (2)-
(4), we have so far taken for granted that role-playing is fully explicable in terms of either
of the role triad alone. To formalize a general role module may require however that
role-playing be well explained only by the role triad as a whole. This would be equivalent
to the following full grounding of the fact about Mary’s playing a student role:
,
,
⇒ (5)
Note that, by definition, (5) entails the following partial grounding: (resp. , ) → . It will be a promising line of
research to deepen our grounding-based conceptualization of roles, for example by
exploiting the logic of grounding [37-39]. Once a general formalization of roles is
available, further work includes (i) its specialization against a specific ontological
background (see e.g., [40] based on the BFO upper ontology) and (ii) its application to
an ontological analysis of specific roles such as social roles [41] and thematic roles [42]
together with a domain-specific practical application (see e.g., [43,44]).
References
[1] J. J. Odell, H. V. D. Parunak and M. Fleischer. Modeling agent organizations using roles. Software and
System Modeling, 2(2), 76-81, 2003.
[2] O. Pacheco and J. Carmo. A role based model of normative specification of organized collective agency
and agents interaction. Autonomous Agents and Multiagent Systems, 6(2), 145-184, 2003.
[3] J. P. A. Almeida, G. Guizzardi and P. S. Santos Jr. Applying and extending a semantic foundation for role-
related concepts in enterprise modelling. Enterprise Information Systems, 3:3, 253-277, 2009.
[4] M. S. Fox, M. Barbuceanu, M. Gruninger and J. Lin. An organisation ontology for enterprise modelling.
In M. Prietula, K. Carley and L. Gasser (Eds.), Simulating Organizations: Computational Models of
Institutions and Groups, Menlo Park, CA: AAAI/MIT Press, 131-152, 1998.
[5] G. Boella and L. van der Torre. A foundational ontology of organizations and roles. In M. Baldoni and U.
Endriss (Eds.), Declarative Agent Languages and Technologies IV (DALT 2006), Lecture Notes in
Computer Science, vol. 4327, Berlin, Heidelberg: Springer-Verlag, 78-88, 2006.
[6] E. Bottazzi and R. Ferrario. Preliminaries to a DOLCE ontology of organizations. International Journal of
Business Process Integration and Management (Special Issue on Vocabularies, Ontologies and Business
Rules for Enterprise Modeling), 4(4), 225-238, 2009.
[7] G. Boella, L. van der Torre and H. Verhagen. Roles, an interdisciplinary perspective. Applied Ontology,
2(2), 81-88, 2007.
[8] F. Loebe. Abstract vs. social roles: Towards a general theoretical account of roles. Applied Ontology, 2(2),
127-158, 2007.
[9] V. Genovese. Towards a general framework for modelling roles. In G. Boella, L. van der Torre and H.
Verhagen (Eds.), Normative Multiagent Systems, number 07122 in Dagstuhl Seminar Proceedings.
Internationales Begegnungs- und Forschungszentrum für Informatik (IBFI), Schloss Dagstuhl, Germany,
2007.
[10] F. Steimann. On the representation of roles in object-oriented and conceptual modelling. Data &
Knowledge Engineering, 35(1), 83-106, 2000.
[11] F. Toyoshima. Three facets of roles in foundational ontologies. In L. Jansen, D. P. Radicioni and D.
Gromann (Eds.), Proceedings of the 4th Joint Ontology Workshops (JOWO 2018), Cape Town, South
Africa, September 17-18, 2018, CEUR Workshop Proceedings, vol. 2205, 12 pages.
[12] D. M. Armstrong. Truths and Truthmakers. Cambridge: Cambridge University Press, 2004.
[13] H. Beebee and J. Dodd. (Eds.). Truthmakers: The Contemporary Debate. Oxford: Oxford University
Press, 2005.
[14] A. Botti Benevides and C. Masolo. States, events, and truth-makers. In P. Garbacz and O. Kutz (Eds.),
Proceedings of the 8th International Conference of Formal Ontology in Information Systems (FOIS
2014), Rio de Janerio, Brazil, September 22-25, 2014, Amsterdam: IOS Press, 93-102.
[15] N. Guarino and G. Guizzardi. Relationships and events: Towards a general theory of reification and
truthmaking. In G. Adorni, S. Cagnoni, M. Gori and M. Maratea (Eds.), Proceedings of the 15th
International Conference of the Italian Association for Artificial Intelligence on Advances in Artificial
Intelligence (AI*IA 2016), Genova, Italy, November 29-December 1, 2016, Lecture Notes in Computer
Science, vol. 10037, Springer, 237-249.
[16] N. Guarino, T. P. Sales and G. Guizzardi. Reification and truthmaking patterns. In J. C. Trujillo et al.
(Eds.), Proceedings of the 37th International Conference on Conceptual Modeling (ER 2018), Xi’an,
China, October 22-25, 2018, Lecture Notes in Computer Science, vol. 11157, Springer, 151-165.
[17] B. Schnieder and F. Correia. Grounding: An opinionated introduction. In B. Schnieder and F. Correia
(Eds.), Metaphysical Grounding: Understanding the Structure of Reality, Cambridge: Cambridge
University Press, 1-36, 2012.
[18] K. Trogdon. An introduction to grounding. In M. Hoeltje, B. Schnieder and A. Steinberg (Eds.), Varieties
of Dependence: Ontological Dependence, Grounding, Supervenience, Response-Dependence (Basic
Philosophical Concepts), Munich: Philosophia Verlag, 97-122, 2013.
[19] M. J. Raven. Ground. Philosophy Compass, 10(5), 322-333, 2015.
[20] K. Fine. The question of realism. Philosophers’ Imprint, 1(2), 1-30, 2001.
[21] K. Fine. Guide to ground. In B. Schnieder and F. Correia (Eds.), Metaphysical Grounding: Understanding
the Structure of Reality, Cambridge: Cambridge University Press, 37-80, 2012.
[22] A. Wilson. Metaphysical causation. Noûs, 52(4), 723-751, 2018.
[23] K. Mulligan and F. Correia. Facts. In E. N. Zalta (Ed.), The Stanford Encyclopedia of Philosophy (Winter
2017 Edition), https://plato.stanford.edu/archives/win2017/entries/facts/ (Last accessed on August 14,
2019).
[24] D. M. Armstrong. A World of States of Affairs. Cambridge: Cambridge University Press, 1997.
[25] T. C. Dixon. What is the well-foundedness of grounding? Mind, 125(498), 439-468, 2018.
[26] A. Bird. Overpowering: how the powers ontology has overreached itself. Mind, 125(498), 341-383, 2016.
[27] R. Arp, B. Smith and A. D. Spear. Building Ontologies with Basic Formal Ontology. Cambridge, MA:
The MIT Press, 2015.
[28] R. Turner. Specification. Minds & Machines, 21(2), 135-152, 2011.
[29] W. D. Duncan. Ontological distinctions between hardware and software. Applied Ontology, 12(1), 5-32,
2017.
[30] L. Vieu, S. Borgo and C. Masolo. Artefacts and roles: Modelling strategies in a multiplicative ontology.
In C. Eschenbach and M. Grüninger (Eds.), Proceedings of the 5th International Conference (FOIS 2008),
Saarbrücken, Germany, October 31 - November 3, 2008, Amsterdam: IOS Press, 121-134.
[31] M. Donnelly. Relative places. Applied Ontology, 1(1), 55-75, 2005.
[32] R. Mizoguchi, E. Sunagawa, K. Kozaki and Y. Kitamura. A model of roles within an ontology
development tool: Hozo. Applied Ontology, 2(2), 159-179, 2007.
[33] G. Guizzardi. Agent roles, qua individuals and the counting problem. In A. Garcia, R. Choren, C. Lucena,
P. Giorgini, T. Holvoet and A. Romanovsky (Eds.), Software Engineering for Multi-Agent Systems IV,
SELMAS 2005, Lecture Notes in Computer Science, vol, 3914, Springer, Berlin, Heidelberg, 143-160,
2005.
[34] C. Masolo, G. Guizzardi, L. Vieu, E. Bottazzi and R. Ferrario. Relational roles and qua-individuals. In
G. Boella, J. Odell, L. van der Torre and H. Verhagen (Eds.), Proceedings of the AAAI Symposium on
Roles, an interdisciplinary perspective, Arlington, Virginia, November 4-6, 2005, AAAI Press, 103-112.
[35] C. W. Bachman. The role data model approach to data structures. In S. M. Deen and P. Hammersley
(Eds.), Proceedings of the International Conference on Data Bases, University of Aberdeen: Heyden &
Son, 1-18, 1980.
[36] F. Steimann. The role data model revisited. Applied Ontology, 2(2), 89-103, 2007.
[37] K. Fine. The pure logic of ground. Review of Symbolic Logic, 5(1), 1-25, 2012.
[38] L. deRosset. On weak ground. Review of Symbolic Logic, 7(4), 713-744, 2014.
[39] L. deRosset. Better semantics for the pure logic of ground. Analytic Philosophy, 56(3), 229-252, 2015.
[40] F. Toyoshima. Roles and their siblings in Basic Formal Ontology. In Proceedings of the 10th
International Conference on Biomedical Ontology (ICBO 2019), Buffalo, NY, USA, July 30 - August 2,
2019, accepted.
[41] C. Masolo, L. Vieu, E. Bottazzi, C. Catenacci, R. Ferrario, A. Gangemi and N. Guarino. Social roles and
their descriptions. In D. Dubois, C. Welty and M. A. Williams (Eds.), Principles of Knowledge
Representation and Reasoning: Proceedings of the 9th International Conference (KR 2004), Whistler
British Columbia, Canada, June 2-5, 2004, 267-277.
[42] J. F. Sowa. Knowledge Representation: Logical, Philosophical and Computational Foundations.
Brooks/Cole, 2000.
[43] A. Goy, D. Magro and M. Rovera. On the role of thematic roles in a historical event ontology. Applied
Ontology, 13(1), 19-39, 2018.
[44] F. Toyoshima. Representing value: Function, capability and role. In Proceedings of the 5th Joint
Ontology Workshops (JOWO 2019), Graz, Austria, September 23-25, 2019, accepted.