=Paper= {{Paper |id=Vol-1696/paper4 |storemode=property |title=Gibsonian Modeling of Users in Social Networks |pdfUrl=https://ceur-ws.org/Vol-1696/paper4.pdf |volume=Vol-1696 |authors=Alice Ruggeri,Guido Boella |dblpUrl=https://dblp.org/rec/conf/lrec/RuggeriB16 }} ==Gibsonian Modeling of Users in Social Networks== https://ceur-ws.org/Vol-1696/paper4.pdf
                           Gibsonian Modeling of Users in Social Networks
                                                  Alice Ruggeri, Guido Boella
                                                    University of Turin, Italy
                                 Center for Cognitive Science, Department of Computer Science
                                            {ruggeri@di.unito.it, boella@di.unito.it}

                                                                 Abstract
In recent days, social networks are creating huge amounts of data that need to be managed in intelligent ways. Ontologies always
play important roles in these contexts: users and social objects may refer to concepts and this can provide efficient methods to store,
retrieve and recommend contents. Everything, however, relies on the concept of interaction. Contents are produced when people interact
and social objects are used in some way. In the light of this, we present a novel interaction-based ontological approach to deal with
social networks data, managing growth and complexity. In particular, we revisit the standard methodology of computational ontologies
proposing a framework where objects and users are defined as compositions of atomic semantic information, avoiding preventive and
static identification of the system’s players. Our method is inspired by the work of James Gibson, who defined an ecological view of the
human perception based on objects’ natural affordances, in which objects spontaneously give cues about how they can be used depending
on the user who is actually interacting. The idea is that while social objects and users can potentially grow without limits, the spectrum
of all the possible interactions can be the product of limited (and much more simple to represent) links between users and objects’ atomic
semantic information. In this sense, if a user ‘x’ acts on a social object ‘y’, it means that some property of ‘x’ are activated by the action
(i.e., the user embodies a specific role), and some property of ‘y’ makes the action physically possible (i.e., it allows the action to be
performed). In this paper, we show how an interaction-based ontological view can reduce manual efforts while preserving the control
social networks data.
Keywords: Gibsonian Affordances, Ontologies, Social Networks


                     1.    Introduction                                  carries its own functionalities with itself or it inherits them
Social Networks are web-based platforms where users with                 from a superclass. While this perfectly works in several
different interests and properties interact and live in a kind           scenarios, we want to stress the fact that the dynamic part
of virtual second life. Indeed, this has been a real name                of the architecture (let us now use terms like actions, inter-
for one of them, SecondLife, where people used to build                  actions, messages, functionalities, and operators for identi-
avatars, i.e., 3D self-personifications in an invented world.            fying this concept) must inhabit inside the objects. In other
The aim of this paper, however, is not to overview all the               words, what can happen with an object has to be defined
range of the existing platforms, nor to to make distinctions             in the object itself. This somehow freezes the high vari-
and, least of all, not to face social aspects and problematics           ability of how an object can be used, and, in general, how
related to the use of such technology. Actually, we want                 agents can interact with it. Centering Social Networks data,
to focus the attention on how these data coming from users               functionalities and visualization directly on users needs the
interactions in social platforms are of scientific interest in           rest of the world to be as much flexible as possible from a
terms of knowledge representation and ontology modeling.                 representational point of view.
We usually refer to the term ontology as a set of formal de-             Most of the times, working on objects as main concepts to
scriptions and tools to represent a specific domain (or a part           be defined is both practical and sufficient. However, this
of it) in an objective way. This is usually reflected in a defi-         strictly depends on the nature of the domain under defini-
nitions of objects with fixed properties, and relations among            tion. For example, social networks are extremely dynamic
them that depict the dynamic aspect of the representation.               environments where OO-style objects like users, interests,
For instance, we can think at the following description for              and locations could be secondary with respect to the inter-
a generic object A:                                                      actions that make them active and communicating.
     An object A is defined by some attribute p1 , p2 ,                  Our idea regards an ontological modeling of the behavior
     and p3 which can have some values within a spe-                     of intelligent agents, built on top of the concept of affor-
     cific numeric range like [1, 10] or among a set of                  dance introduced by (Gibson, 1977) to describe the process
     nominal values, e.g., low, medium, high. Then,                      underlying the perception. In his work, Gibson (Gibson,
     A can exhibit the functionalities f1 and f2 to                      1977) claimed that objects assume different meanings de-
     the external world, representing its dynamic part,                  pending on the context, and more specifically, taking into
     i.e., its behaviour.                                                account the animal species that interact with them. Im-
                                                                         plementing this concept in a social network environment
Representing the world by starting from objects and rela-                would lead to ontologies based on interactions rather than
tions between them is a classic and intuitive way to make                on objects. For instance, let us quickly consider an example
the things working both conceptually and at an application               where a user (data creator) publishes on the network some
level. Object-Oriented programming (OOP) is one of the                   comment about a hole in a specific street. Then, let us as-
most successful programming paradigms that uses this ar-                 sume we have two types of users (consumers), a cyclist and
chitecture to represent internal data structures. Each object            a public-transport passenger, respectively. While the object
  under consideration has an high priority for the formers, it RQ #4 how to capture and shape the dynamism and the vari-
  can be probably worthless for the latters. In a classic rep-           ability of the interactions depending on who/what is
  resentation scheme, each object-user combination needs to              interacting
  be thought and formalized a priori, manually checking all
  the possible cases with the relative contraints. Note that this RQ #5 how to enable smart access strategies in dynamic
  can be extremely consuming in terms of manual effort (cre-             and multimensional data (fuzzy search, graph search,
  ation / management of interventions) and carry to unflexi-             cross-aspects search, etc.)
  ble and redundant representations which do not embed the          In general, in social networks, a multitude of combinations
  concept of knowledge sharing. In addition to this, not only       of aspects must be taken into account depending on several
  objects (like street holes) and user types can create a large     factors like time, locations, interests, and so on. These are
  space of representation, but other dimensions can be added,       not well represented by classic paradigms where the world
  further multiplying the problem. For instance, the basis          is a matter of objects and relationships, since this does not
  of the network is the type of interaction, i.e., what people      cope with the explosion of cases to define a priori.
  can do, creating a three-dimensional space user-interaction-
  object which results to be untreatable with classic First Or-     3. Cognitive Background and Related Work
  der Logic-like representations (Baldoni et al., 2006).            In this section, we overview the main foundations from
  Along this contribution, we will talk about ways of think-        which our contribution is mostly inspired. Since our pro-
  ing at knowledge by means of objective and subjective rep-        posal has to do with how ontologies can be used in infor-
  resentations, highlighting limits and workarounds. After-         mation systems, it is worth to cite important works like
  wards, we will present our idea of interaction-based com-         (Guarino, 1998)(Gruber, 1995) that deeply describe main
  putational ontologies as an approach to solve some of the         issues and state-of-the-art approaches. Fiske and Taylor
  discussed issues, proposing an implementation to represent        (Fiske and Taylor, 2013) highlight important features re-
  social networks data. We, finally, conclude the paper with        lated to Social Cognition, and computational approaches
  a list of future work directions and open problems.               are needed to better fit users’ activity.
                                                                    The starting point of the discussion is the use of formal on-
                 2.   Research Questions                            tologies. In general, formal ontologies are inspired to the
  Social networks have the need of structuring all the data         basic principles of the First Order Logic (Smullyan, 1995),
  in efficient ways, not only from a computational perspec-         where the world is explained by the existence of defined
  tive, but rather considering conceptual schemes that better       objects and fixed relationships among them. This belongs
  enhance the user experience itself.                               to a physical and static view of the world, since this repre-
  In real-life scenarios, it is common to find complex cases        sentation is able to treat only the existence of objects and
  where data coming from different sources can cross sev-           relationships. The same actions are offered to all agents in-
  eral aspects, ranging from bureaucracy issues to restaurant       teracting with the object, independently of the properties of
  reviews. Managing both the quantity and the sparsity of           these agents.
  the data is the first problem to tackle with advanced tech-       Our aim is to manage concepts which have different per-
  niques. Then, spreading the data to users according to inter-     spectives depending on the kind of agent or species is inter-
  ests, actual and current needs, and with the right priority is    acting with them, instead of having an object duplicated in
  even more challenging. Still, not only social networks usu-       different classes according to the different possible behav-
  ally have to notify users autonomously, but they also have        iors afforded to different agents. A social-driven ontology
  to answer to specific user queries. Indeed, the concept of        would lie between two extremes, as the first-person ontol-
  search in social networks is crucial and partially different      ogy mentioned by Searle (Searle, 1998).
  from standard information retrival tasks of common search         For example, the door provides two different ways to inter-
  engines. In fact, the latters have to index data (text, images,   act (the set of methods, if we want to use a programming
  videos, etc.) to be retrieved by means of classic few-words       language terminology): a way for a human user and on the
  user queries, whereas, in social networks, queries connect        other side the one for a cat. These two ways have some
  locations with people, crossing communities, events, and          common actions with different implementations, but they
  specific time ranges. All this is even made more compli-          can also offer additional actions to their agents or players.
  cated by the presence of continuously-changing informa-           For example, a human can also lock a door with the key or
  tion like hashtags, emotional states, and smartphones ap-         shut it, whereas a cat cannot do it. The behavioral conse-
  plication data.                                                   quence of “how to interact with the door” can be “opened
  From a computational and ontological perspective, the             by the handle” rather than “pushed leaning on it”, and the
  challenges faced by this contribution are the following:          way the action will be performed is determined by who is
                                                                    the subject of the action.
RQ #1 how to minimize manual efforts in building computa-           The second example has a different character, since it refers
      tional ontologies                                             to a technological artifact, i.e., a printer. As such, the ob-
RQ #2 how to represent such complex data maximizing the             ject can have more complex behaviours and above all the
      sharing of the whole knowledge in a social network            behaviours do not depend only on the physical properties
                                                                    of the agents interacting with it but also with other proper-
RQ #3 how to represent the data without affecting the flexi-        ties, like the role they play and thus the authorizations they
      bility of objects and agents interactions                     have. The printer provides two different roles to interact
with it (the set of methods): the role of a normal user, and     novel way of estimating kind of affordances at natural lan-
a role of super user. The two roles have some common             guage level relying on statistical analysis. Finally, it is
methods (roles are classes) with different implementations,      important to refer to (Steedman, 2002), where the authors
but they also offer other different methods to their agents.     demonstrated that natural language grammar and planned
For example, normal users can print their documents and          actions are related systems.
the number of printable pages is limited to a maximum de-        Dynamic taxonomies (Sacco, 2000) exploit a set of in-
termined (the number of pages is counted, and this is a role     stances classified in a taxonomy to create latent connections
attribute associated to the agent).                              between nodes belonging to different paths. In fact, if one
The third example we consider is of a totally different kind.    instance is classified under two concepts on different paths
There is no more physical object, since the artifact is an       means that there is some link between them that the orig-
institution, i.e., an object of the socially constructed re-     inal taxonomy was not aware of. This approach is useful
ality (Searle, 1995). Let us consider a university, where        to browse a taxonomy by iteratively selecting nodes for fil-
each person can have different roles like professor, student,    tering the data, and in this sense it has some relations with
guardian, and so forth. Each one of these will be associ-        every work on making structured knowledge dynamic and
ated to different behaviours and properties: the professors      changeable with respect to some context.
teach courses and give marks, and have an income; the stu-
dents give exams, have an id number, and so forth. Here the                        4.    The Approach
behaviour does not depend anymore on the physical prop-          Social networks are a modern way people use to commu-
erties but on the social role of the agent.                      nicate and share information in general. Facebook, Twitter,
Mental models have been introduced by Laird (Johnson-            Flickr and others represent platforms to exchange personal
Laird, 1983), as an attempt to symbolic representations of       data like opinions, pictures, thoughts on world-wide facts,
knowledge to make it computable, i.e., executable by com-        and related information. All these communities rely on the
puters. This concept is the basis of the most important          concept of user profile. A user profile is generally a set of
human-computer cognitive metaphor (Gentner and Stevens,          personal information that regard the user in itself as well
2014).                                                           his activity within the community.
Another related work which can be considered as a starting       Understanding the reference prototype of a user is cen-
point of our analysis is about the link between the Gestalt      tral for many operations like information recommendation,
theory (Köhler, 1929; Wertheimer et al., 1927) and the con-     user-aware information retrieval, and user modeling-related
cept of affordance in the original way introduced by Gib-        tasks. In this context, the concept of affordance can be
son for the perception of objects. Wertheimer, Kohler and        used in several scenarios. First, it can be a way to per-
Koffka, the founders of the Gestalt movement (Wertheimer         sonalize the content to show to the user according to his
et al., 1927), applied concepts to perception in different       interests and activity. This is massively done in today’s
modalities. In particular, it is important to remind the prin-   web portals, where advertising is more and more adapted
ciple of complementarity between “figure” and “ground”.          to the web consumers. Secondly, the whole content shared
The same concept is applicable in natural language under-        by ’user friends’ can be filtered according to his profile, in
standing. For instance, let us think at the sentence “The        the same way as in the advertising case. Notice that this
cat opens the door”. In this case, our basic knowledge of        does not have to do with privacy issues. In fact, a user may
what the cat is and how it moves can be our ground to un-        be not interested in all facts and activities coming from all
derstand the whole figure and to imagine how this action is      his friends. Social networks started taking into consider-
performed. In other words, the Gestalt theory helps us say       ation these issues, and our proposal regards an ontological
that the tacit knowledge about something (in this case, how      modeling of the data that could autonomously and naturally
the cat uses its paws) is shaped on the explicit knowledge of    work in this sense.
“what the door is”. Following this perspective, the concepts     Commonly, we can think at the interactions in a network as
are not analyzed in a dyadic way, but in a triadic manner.       classes managing rules and constraints to match users with
Considering the literature in Object-Oriented programming        fixed categories or objects (the terms object and category
(OOP), it is worth citing Powerjava (Baldoni et al., 2006),      are interchangeable, referring to “things” that “lives” in the
i.e., an extension of the Java language where an objective       network around the users. A scheme of this scenario is il-
and static view of its components is modified and replaced       lustrated in Figure 1. Notice that this approach creates one
on the basis of the functional role that objects have inside.    class for each combination user-category (when it is seman-
The behavior of a particular object is studied in relation to    tically allowed), and it produces a large set of unflexible and
the interaction with a particular user. In fact, when we think   predetermined interactions to be formally defined.
at an object, we do it in terms of attributes and methods,       For example, if we consider the class StreetHole represent-
referring to the interaction among the objects according to      ing the street holes instances in the platform, we need to
public methods and public attributes. The approach is to         model all the agents that can interact with it, like CarA-
consider Powerjava-roles as affordances, that is, instances      gent (a class modeling the instances of people moving with
that assume different identities dependeing on the agents.       cars), BikeAgent, and so forth. The problem is that, with
Weissensteiner and Winter (Weissensteiner and Winter,            this methodology, all possible agents and objects have to
2004) focus on landmarks contained in texts to analyze           be defined a priori in the ontology, without an appropriate
their role in the general understanding of routes. Distri-       uncertainty management. In our approach, we do not look
butional Semantics (Baroni and Lenci, 2010) represents a         for a complete coverage of the interacting agents/objects,
Figure 1: Classic view of single interactions connecting          Figure 2: In a property-based interaction scheme, cate-
users and categories. Each interaction has its own “life”         gories and users disappear from the graph since they be-
and it is different from the others, in the sense that it does    come simple compositions of features, while the latters
not share any information nor overlapping degree with the         constitute the new basis of the representation. Each interac-
other ones. The distance between the points do not carry          tion is thus defined as a set of user/agent properties connect-
any information.                                                  ing a set of category/object properties, producing area-like
                                                                  representations. However, notice that each interaction is ac-
                                                                  tually formed as multiple and non-contiguous areas, while
since we actually do not represent them as physical con-
                                                                  the figure has been only created to easily communicate the
cepts, while we only manage sets of fine-grained semantic
                                                                  concept.
information units that everything (i.e., agents rather than
objects) can have in a specific context/time scenario.
Our idea is illustrated in Figure 2. Objects and users are             age, sex, marital status, type of work, location,
substituted by the concept of property (i.e., a semantic in-           and a value of affinity for all the objects in the
formation unit), on which interactions directly lie. More in           environment (her/his interests)
detail, each interaction is defined as a set of user features
connecting a set of object features, producing area-like rep-     In the same way, objects share a set of numeric and nominal
resentations. This way, the need of constructing classes for      property O = {o1 , o2 , ..., om }. Examples of them are:
managing all the possible users ∗ actions ∗ objects falls
into an m + n space, where m is the number of user proper-             bureaucracy, building, city mantenance, sport,
ties and n is the number of object properties (m and n may             education, news, kids, nature, tourism, shopping,
have a certain overlapping degree, however).                           lost and found, public transport, personal trans-
In this section, we propose a way to model social net-                 port, hotels, restaurants, culture, entertainment,
works data in a flexible way. As we already anticipated,               animals.
in most social networks people can participate in the net-
work through a set of interactions. For instance, some of         An example of object vector is the following, representing
them could be the following:                                      a thermal spa in the city centre:

     {to buy, to read, to sell, to eat, to drink, to pay               object-vector (a thermal spa) public trans-
     attention, to work, to learn, to play, to know, to                port:0.4, bureaucracy:0.0, building:0.2, city:0.5,
     relax, to participate}                                            mantenance:0.0,       sport:0.4,    education:0.2,
                                                                       news:0.0, kids:0.2, nature:0.7, tourism:0.5,
Each interaction is defined as two sets of properties or fea-          shopping:0.2, lost and found:0.4, personal trans-
tures or semantic information unit, for the users and for the          port:0.6, hotels:0.3, restaurants:0.6, culture:0.0,
objects, respectively. A agent/user or a category/object can           entertainment:1.0, animals:0.0
be associated to a property with a certain weight. More in
detail, the value for a property can be a value in the range      The wights represent a value of how a specific object is re-
[0, 1] representing a degree of affinity within the social net-   lated to a property. In the example, a thermal spa results to
work environment, or a nominal value from a given set S           be more related to entertainment and transportation rather
(Figure 3).                                                       than to bureaucracy and animals. This way, users and ob-
All the users (also called agents and subjects in our             jects are defined as vectors in these two multi-dimensional
examples and figures) share a set of properties A =               spaces, according to the Vector Space Model (Salton et al.,
{a1 , a2 , ..., an }. Some example of user features are:          1975). Notice that, in this manner, objects that present a
Figure 4: Subjects/users and objects/categories can assume a value in the range [0, 1] for each specific property in the social
network environment. All users and objects are thus represented as vectors. In the same way, a specific interaction becomes
a two-vectors model that represents the association weights with the subjects and the objects properties, respectively. If a
property is not set for a certain user-vector / category-vector / user-interaction-vector / category-interaction-vector, this is
treated as a constraint of having a 0-value for any other vector that will be compared with it (otherwise the total similarity
value between the two vectors will be set to 0).


                                                                  Scaling (Kruskal, 1964) and Self-Organizing Maps (Koho-
                                                                  nen, 2001), or by manually-computed ranges.
                                                                  The first phase concerns the development of the interac-
                                                                  tion ontology, where the domain experts have to edit a first
                                                                  sketch (even if this can be tuned by users activities dynam-
                                                                  ically) of the taxonomy of the interactions. Initially, we
                                                                  considered a flat organization where interactions work in-
                                                                  dependently, but the system can work with hierarchy-based
                                                                  constructions as well. In detail, the knowledge engineer has
                                                                  to create the two vectors of the model (the one for the user
                                                                  and the one for the object) for each interaction. An example
                                                                  is shown later in this section.
                                                                  At this point, once the interaction ontology with all the
                                                                  model vectors are created, a user in the network can act
Figure 3: Interaction-centered knowledge representation.          according to the adherence between his/her properties with
Interactions are defined by means of two sets of properties,      the ones of the existing interactions (their left-side vector
i.e., for the users and for the categories. Users (black nodes    in Figure 4), dynamically, and in real-time. The adherence
on the left) and categories (black nodes on the right) satisfy-   is computed by means of the well-known cosine similarity.
ing these constraints can participate to the interaction. All     From the other side, all the objects are represented as vec-
the interactions are structured in a taxonomy, where sub-         tors of features as well. One object can be represented by a
classes inherit both sets of properties from the superclass.      value of affinity with all the other objects. This is both prac-
Secondary, users and categories are defined as simple sets        tical and plausible, since one object can be related to others
of properties / features.                                         in some way. For example, the category public transport
                                                                  has a significant degree of affinity with the category private
                                                                  transport, and it is much higher than what it could be with
similar conceptual nature may change its property status          the category sport. There are several ways for computing
and so becoming different things depending on the context.        such graded categorizations in automatic ways also in tax-
Each interaction, in the same manner, is defined as two           onomy structures as in (Kim and Candan, 2006); however,
vectors of weights (one concerning the user side, and             we think that such process must be done manually (or with
one for the objects), and it can be placed within a tax-          a manual support), trying to capture the actual semantics
onomy inheriting all the properties from its parents with         according to the specific domain of application.
some tuning of the weights. Notice that in case of non-           To sum up, the initial modeling efforts lie in the configura-
numerical attributes, the weights can be numerical trans-         tion of the interactions by weighting user and object vector
formation obtained by techniques like Multi-Dimensional           weights. An example of user-vector model for the interac-
tion to relax is the following:                                    access strategies, since it is the model used for queries and
                                                                   retrieval by definition (RQ #5).
      user-vector age:’any’, location:’any’, sex:’any’,
      public transport:0.4, bureaucracy:0.0, build-
      ing:0.2, city:0.5, mantenance:0.0, sport:0.7,                       6.        Conclusions and Future Works
      education:0.2, news:0.3, kids:0.2, nature:0.8,               In this paper, we proposed an idea for representing the
      tourism:0.8, shopping:0.8, lost and found:0.0,               knowledge of highly dynamic environments like social net-
      personal transport:0.6, hotels:0.4, restau-                  works and Web Sharing sites. Indeed, these kind of infor-
      rants:0.6,    culture:1.0,    entertainment:1.0,             mation need to be carefully organized to remain manage-
      animals:0.3                                                  able while making the interaction itself enhanced. We first
                                                                   started the discussion by thinking at a classic Social Net-
Then, users dynamically change their feature vector
                                                                   work scenario where users are associated to interests and
through their own activity in the network (and therefore
                                                                   locations, acting over (virtualized) real-life objects. Then,
they constantly change their interaction scenarios). In ad-
                                                                   multiple interactions can take place by means of several
dition, as in the basic idea of Dynamic Taxonomies (Sacco,
                                                                   combinations of these concepts, thus the knowledge com-
2000) by which instances classified under different objects
                                                                   plexity and the relative management becomes interesting as
are viewed as latent connections between the latters, a real-
                                                                   much as it gets harder. In future works, we will implement
time adjustment of the weights is not only done by user-
                                                                   these ideas on real Social Networks data. We advocate an
side, but also on the object vectors. In fact, initial manually-
                                                                   underlying formalization in first-order logic, in line with
constructed object vectors can exploit the real use carried
                                                                   flat reification-based approaches such as ((Hobbs, 2008)
by users activities to find unknown affinity connections (or
                                                                   and (Robaldo, 2011). As pointed out in the introduction,
to moderate the ones already known). This prevents from
                                                                   a three-dimensional space user-interaction-object results to
incorrect configurations in the cold start.
                                                                   be untreatable with classic First Order Logic-like represen-
 5.    Definitions and Validity of the Approach                    tations (Baldoni et al., 2006), while reification allows to
                                                                   keep complexity under strict control, thus providing a scal-
The entities involved in our proposal are the following:           able instrument to implement our model. Then, we will
  • Property. Also called semantic information unit,               integrate this approach with automatic techniques to ex-
    it represents the central brick of the world under             tract, recommend and visualize interaction-based and user-
    representation. Every agent/object/interaction is built        centered contents by using the proposed ontology mod-
    on top of it.                                                  eling, relying on semantic technologies and visualization
                                                                   tools such as (Di Caro et al., 2011; Boella et al., 2014; Can-
                                                                   dan et al., 2012; Cataldi et al., 2013).
  • Agent/Object. It is a set of pairs < p, v > where
    p is a property and v is a value within its domain D(p).                   7.    Bibliographical References
                                                                   Baldoni, M., Boella, G., and Van Der Torre, L. (2006).
  • Interaction. An interaction is a pair of left and right          powerjava: ontologically founded roles in object ori-
    property sets, defining who interacts with what.                 ented programming languages. In Proceedings of the
                                                                     2006 ACM symposium on Applied computing, pages
                                                                     1414–1418. ACM.
  • Interaction Taxonomy. Interactions are organized in            Baroni, M. and Lenci, A. (2010). Distributional memory:
    a taxonomical structure such that if an interaction Ip           A general framework for corpus-based semantics. Com-
    is parent of an interaction Ic , then all left and right         putational Linguistics, 36(4):673–721.
    property sets of Ip are inherited by Ic .
                                                                   Boella, G., Di Caro, L., Ruggeri, A., and Robaldo, L.
                                                                     (2014). Learning from syntax generalizations for auto-
Agents and objects are compositions of properties, so there          matic semantic annotation. Journal of Intelligent Infor-
is no need to build user- and object ontologies. This mini-          mation Systems, 43(2):231–246.
mizes manual efforts in building computational ontologies          Candan, K. S., Di Caro, L., and Sapino, M. L. (2012). Phc:
(see Research Question (RQ) #1 in Section 2.) exploiting             Multiresolution visualization and exploration of text cor-
the efficacy of the vectorial representations. In the same           pora with parallel hierarchical coordinates. ACM Trans-
way, the model maximizes the sharing of knowledge since              actions on Intelligent Systems and Technology (TIST),
objects and agents use the same feature space (RQ #2).               3(2):22.
Then, the flexibility of the interactions is not affected by       Cataldi, M., Caro, L. D., and Schifanella, C. (2013). Per-
such representation (RQ #3) since they directly rely on              sonalized emerging topic detection based on a term ag-
them by being modeled in the same fashion by two fea-                ing model. ACM Transactions on Intelligent Systems and
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