<!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Archiving and Interchange DTD v1.0 20120330//EN" "JATS-archivearticle1.dtd">
<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta>
      <journal-title-group>
        <journal-title>Journal of Human Resources in Hospitality &amp; Tourism 17
(2018) 200-221. URL: https://doi.org/10.1080/15332845.2017.1340763. doi:10.1080/15332845.
2017.1340763. arXiv:https://doi.org/10.1080/15332845.2017.1340763.
[12] D. Gursoy</journal-title>
      </journal-title-group>
    </journal-meta>
    <article-meta>
      <article-id pub-id-type="doi">10.1177/0894439310386567</article-id>
      <title-group>
        <article-title>Ontology-Driven Modelling of Personal data for Professional Social Media Platforms (PSMPs)</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Bahadır Aktaş</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Luís Ferreira Pires</string-name>
          <email>l.ferreirapires@utwente.nl</email>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Rodrigo Calhau</string-name>
          <email>calhau@ifes.edu.br</email>
          <xref ref-type="aff" rid="aff0">0</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Adem Akbıyık</string-name>
          <email>adema@sakarya.edu.tr</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Federal Institute of Espírito Santo</institution>
          ,
          <addr-line>Vitória</addr-line>
          ,
          <country country="BR">Brazil</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Sakarya University, Management Information Systems Department, Business Faculty</institution>
          ,
          <addr-line>Serdivan, Sakarya</addr-line>
          ,
          <country country="TR">Turkiye</country>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>University of Twente, Semantics, Cybersecurity and Services group</institution>
          ,
          <addr-line>Enschede</addr-line>
          ,
          <country country="NL">the Netherlands</country>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2022</year>
      </pub-date>
      <volume>1301</volume>
      <fpage>0000</fpage>
      <lpage>0001</lpage>
      <abstract>
        <p>Professional Social Media Platforms (PSMPs), of which LinkedIn is the most prominent example, are web-based social networks oriented towards professional networking and career development. PSMPs enable individuals to showcase their work, share content, explore job opportunities, and connect with fellow professionals and colleagues. Workers looking for opportunities can use PSMPs to display their capabilities by publishing digital resumes, while companies looking for employees can use PSMPs to make them known to a broader audience and eventually to post job openings. Although PSMPs can play an important role in the recruitment process, this potential is not fully exploited because the data they hold lack precise semantics and are not machine-actionable. For this purpose, this paper describes the development of an ontology for personal data that aims to give formal semantics to PSMP personal data. This ontology has been developed based on the Unified Foundational Ontology (UFO) and is defined in OntoUML. The paper also describes how this ontology has been beneficially used in the development of a software system that advises job seekers on the skills and competences that they have to acquire to become a better match for a job position.</p>
      </abstract>
      <kwd-group>
        <kwd>engineering</kwd>
        <kwd>Professional Social Network Platforms</kwd>
        <kwd>career-related personal data</kwd>
        <kwd>Unified Foundational Ontology</kwd>
        <kwd>ontology</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>With the increasing popularity of social media, Professional Social Media Platforms (PSMPs), like LinkedIn,
Xing and ResearchGate, became useful instruments for professional networking and career development.
PSMP is a web-based social network oriented to companies and industry professionals looking to make
new business contacts or keep in touch with coworkers, afiliates, and clients [ 1]. According to Statista1,
the number of PSMP users has increased in the last four years, confirming the growing popularity of
these platforms. This increase can also be associated with the vast career-related data PSMPs possess
and the career opportunities they ofer for networking and visibility.</p>
      <p>For workers looking for opportunities, PSMPs serve as platforms for publishing digital resumes. For
companies looking for employees, they serve as platforms to make the companies known to a wider
audience and, more specifically, to post job openings. This means that these platforms contain a wealth
of career information, ranging from an individual’s educational background, work experience, skills,
and professional competences to available jobs and their requirements [1, 2]. Career opportunities
that used to be communicated only through face-to-face meetings or newspaper ads can now reach a
Proceedings of FOIS 2025 Satellite events co-located with the 15th International Conference on Formal Ontology in Information</p>
      <p>ISSN1613-0073
wider audience and are more accessible due to the visibility ofered by PSMPs. However, digitization of
career data brings along some challenges. Although PSMPs, such as LinkedIn, may maintain internal
knowledge models, these are proprietary and not publicly accessible, making them unsuitable for open
reuse or evaluation. As a result, publicly available PSMP data are not machine-actionable and lack
precise semantics. Without precise semantic definitions, data can be misinterpreted, relations between
data may not be revealed, and valuable nuances in career-related data can be missed.</p>
      <p>To address this issue, Ontology-Driven Conceptual Modeling (ODCM) stands out as a promising tool.
ODCM allows the definition of ontological models that give formal semantics to data, enhancing data
comprehension and facilitating their understanding [3]. The Unified Foundational Ontology (UFO) is a
foundation ontology that enables a precise definition of data semantics [ 4], and OntoUML is a UFO
based modeling language defined as a UML profile that can be used to represent ontologies [ 5]. UFO
and OntoUML have been successfully applied to perform ontological unpacking, namely exposing and
analysing the ontological commitments of models, languages and tools for the purpose of evaluation
and improvement in many diferent domains [ 6].</p>
      <p>In this paper, we show how ontological unpacking can enable the extraction of semantic details
from professional data from PSMPs, revealing their layers and uncovering relations between data
elements that might otherwise go unnoticed. We defined an ontology of individual career-related data
found on PSMPs, using the LinkedIn example as a case study, in an ontologically well-founded manner
using ODCM, aiming at making the data machine-actionable. Through this ontology, professional
data become grounded in ontological foundations, and connections between data elements are clearly
articulated.</p>
      <p>This paper is further structured as follows. Section 2 discusses career-related data in PSMPs and
justifies the use of ontologies to give proper semantics to these data. Section 3 outlines the methodology
based on SABiO [7] that we used to develop our reference ontology for online professional data.
Section 4 discusses our reference ontology, our key modeling decisions and how the ontology was
verified. Section 5 discusses some practical implications of using our ontology. Section 6 discusses
related work. Finally, Section 7 gives our final remarks.</p>
    </sec>
    <sec id="sec-2">
      <title>2. Career-Related Data in PSMPs</title>
      <p>Professional Social Media Platforms (PSMP) are social networking platforms focused on professional
networking [8], supporting social networks where relationships move beyond just friendships or casual
connections. They have been specifically designed for business or academic purposes, aiming to of
support professional networking and people interaction [2, 1]. PSMP users often utilize these networks
to showcase their professional credentials, primarily for the purpose of self-promotion often aiming to
tap the platform’s resources for potential employment opportunities and the acquisition of professional
information [9].</p>
      <sec id="sec-2-1">
        <title>2.1. Usage and Functionality</title>
        <p>Networking is considered a major factor in career success in workplaces [10]. Studies show that job
hunters use PSMPs to grow their professional networks [11], and PSMP usage is motivated by the need
for career advancement [12]. Users’ profiles in PSMPs are similar to online resumes and can help users
extend their professional network by establishing a common ground for professional self-promotion. In
addition, active or passive participation in PSMP and disclosure of personal profiles have significant
positive efects on the perceived social connectedness of PSMP users [ 13]. Another perspective on
PSMP usage is from employers, as research shows that evaluating social media profiles is becoming an
integral part of organizational hiring procedures [14]. Employers increasingly rely on social media
profiles, especially those on PSMS platforms, to screen candidates and distinguish their professional
attributes and job fit. Applicants are advised to manage their profiles proactively on these platforms to
clearly demonstrate and present their skills and suitability for potential job opportunities [15]. Figure 1
summarizes the main uses of PSMPs for general, business and academic users [2].</p>
        <p>PSMPs serve as platforms for professional networking and career advancement and host a rich array
of user-generated data, which holds potential for career development, organizational decision-making,
and data-driven insights.</p>
      </sec>
      <sec id="sec-2-2">
        <title>2.2. User’s Career Data</title>
        <p>Career-related data plays an important role in career planning and can be used to enable individuals and
organizations to make informed decisions about career paths and professional growth. By analyzing
career data, an alignment can be achieved between individual aspirations and organizational goals. It
improves human resources management and career development outcomes [16].</p>
        <p>
          These data can also uncover patterns and insights, which enables many diferent applications in
professional settings. For example, a LinkedIn user can create profiles with their employment history,
professional achievements, skills and expertise. Additionally, users can join groups focused on job
opportunities and recruitment, enabling them to build connections, explore job openings, and engage
in discussions [1]. To better understand the data architecture of LinkedIn, Figure 2 visualizes a part
of their data warehouse schema focusing on user and group related data. In this schema, the user
information is structured in three main types: (
          <xref ref-type="bibr" rid="ref1">1</xref>
          ) personal information, (
          <xref ref-type="bibr" rid="ref2">2</xref>
          ) professional information,
and (
          <xref ref-type="bibr" rid="ref3">3</xref>
          ) educational information [1].
        </p>
        <p>However, this schema does not show an important aspect of user information present in LinkedIn,
namely skills, certificates, publications and others. To address these missing components, we studied
LinkedIn’s user profile page to identify data elements that go beyond the schema, enabling a more
comprehensive view of user profiles. LinkedIn ofers various features that can be accessed through
publicly available profile pages of a user. These include a profile summary (user’s biography), skills
(individual’s skill set), and position-related details such as position summary (overview of current
and past roles), position title (the specific job role), company name, and work location. Education
information can be also retrieved if available, including the name of the educational institutions, degree
details, and field of study (user’s academic area) [ 17].</p>
      </sec>
      <sec id="sec-2-3">
        <title>2.3. Motivation for Ontologies</title>
        <p>Career-related data in PSMPs sufer from ambiguity. Job titles, skills, and competences can have diferent
meanings depending on the industry, organization, and region. The lack of commonly understood
definitions makes it challenging to interpret and compare professional qualifications, which leads to
inconsistencies. Traditional approaches fail to address the dynamism and complexity of individuals’
competences and skills since these methods lack the ability to provide a rigorous representation of
career data, which includes skills, experiences, and qualifications [ 18]. These shortcomings led to a
limited and incomplete understanding of an individual’s capabilities and limit the efectiveness of career
planning and development strategies [19]. Initiatives such as HR-XML (Human Resource Extensible
Markup Language) [20], O*Net (Occupation Information Network) [21] or ESCO (European Skills,
Competences, Qualifications, and Occupations) [ 22] aim to address this issue by providing a structured
classification system that links occupations to skills and knowledge.</p>
        <p>O*Net is a US-based database focused on occupational classifications, skills, and work activities. It
aims to improve consistency in job descriptions, and supports workforce planning by defining key
knowledge areas, skills, and abilities for each role. However, O*Net remains a structured database and
lacks the formal rigor of an ontology. It establishes links between occupations and required competences,
however, it does not consider contextual variations, dynamic job requirements, or interdependencies [21].
HR-XML provides a standard format for exchanging HR-related data, improving interoperability in
talent management systems. However, it does not define competences nor establish relationships
between skills and occupations. While HR-XML enables data sharing across HR applications, it does not
resolve ambiguity in competence definitions nor support dynamic job requirement updates [ 20]. ESCO
improves consistency in job descriptions and facilitates workforce alignment by defining essential and
optional competences for each role. However, ESCO remains a taxonomical system rather than an
ontology, which means that it does not fully resolve ambiguity. Although it establishes links between
occupations and skills, it does not account for contextual variations, evolving job requirements, or
dependencies between competences. An ontology-driven approach can overcome these limitations by
providing precise conceptual definitions, modeling contextual relationships, and enabling a structured,
machine-actionable representation of career-related data in PSMPs [23].</p>
        <p>This study aims to model the data represented in professional profiles of individuals shared publicly
on PSMPs (Professional Social Media Platforms) using the Ontology-Driven Conceptual Modeling
(ODCM) approach, the Unified Foundational Ontology (UFO) and OntoUML, ensuring semantic rigor
and fostering semantic interoperability.</p>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>3. Methodology</title>
      <p>
        The ontology we developed serves two main purposes: (
        <xref ref-type="bibr" rid="ref1">1</xref>
        ) as a conceptual common model that provides
clearly defined concepts and relationships to facilitate understanding and communication among
researchers and practitioners: (
        <xref ref-type="bibr" rid="ref2">2</xref>
        ) as a domain model that supports the development of consistent
applications and algorithms, ensuring that PSMP data can be interpreted, processed, and reasoned upon
efectively. Given this dual role, the ontology was developed following SABiO (Systematic Approach
for Building Ontologies) [7], which is an ontology engineering methodology inspired by software
development practices. SABiO structures ontology development into five phases: purpose identification
and requirement elicitation, ontology capture, design, implementation, and test. These phases are
briefly discussed below.
      </p>
      <sec id="sec-3-1">
        <title>3.1. Purpose and Requirements</title>
        <p>In the first step of the SABiO methodology, the objectives of the ontology are defined by engaging
stakeholders, establishing a common vocabulary, specifying functional requirements through
competency questions, identifying non-functional requirements, and structuring the ontology, potentially
decomposing it into sub-ontologies. In this step, we identified the primary purpose of our ontology,
which is to provide a structured representation of skill, competence and job position relevant to career
planning and complex job placements based on online career-related data.</p>
        <p>Competences, skills, and certifications are critical for career development, workforce planning, and
education. Competences, as a combination of skills, knowledge, and behaviors, evolve over time through
experience and learning [24]. An individual’s competences continuously change in relation with their
career development and through ongoing learning processes and this dynamism makes it dificult
to establish clear relationships between competences, job roles, education, and professional growth.
Efectively modeling these relationships is essential for both individuals managing their careers and
organizations developing workforce acquisition strategies.</p>
        <p>Increasing emphasis on lifelong learning and professional development has motivated the need
for a structured representation of career-related data. Traditional career data representations fail to
capture how competences change over time and how they interconnect across diferent professional and
educational contexts [19, 25]. The lack of a rigorous structure in the approach leads to fragmented
understanding of skills, qualifications and experience which in turn limits their value in career planning and
decision-making. Career-related data shows inconsistent representation of competences although they
remain crucial for professional development. Existing frameworks ofer structured classifications [ 22],
but lack the semantic rigor needed to capture contextual dependencies, evolving expertise, and the
interplay between job roles and required qualifications. This limits their efectiveness in supporting
career planning, job matching, and workforce development.</p>
        <p>An ontology-driven approach provides a structured, semantically rigorous model that can formally
define competences, skills, and their interrelations [ 26, 19, 27] . By representing career-related data with
clear conceptual distinctions and relationships, an ontology enables consistent interpretation, semantic
interoperability, and automated reasoning, which can benefit various applications, including AI-driven
career guidance and adaptive workforce planning.</p>
        <p>SABiO prescribes that competency questions should be defined to determine the purpose and the scope
of the ontology. Guided by insights gathered through several one-to-one interviews with practitioners
and academic experts, we formulated the following competency questions for our ontology:
• C1 - What are the structural components of individual competences and how do they relate to
job positions and industry-recognized certifications?
• C2 - What are the distinctions and relationships between a person and their educational
background?
• C3 - What are the conceptual elements that define the relationship between a person and their
job experience in PSMPs?
• C4 - What are the distinctions between competences, skills and certifications in career-related
data?
• C5 - What are the relationships between competence, job position, and required qualifications in
the context of career planning?</p>
        <p>These competency questions could unfold into more detailed inquiries. However, in this paper we
limit our focus to these questions due to space limitations. Our ontology aims to establish a
welldefined, machine-actionable model for structuring career-related data, to ensure semantic precision and
interoperability in PSMP environments.</p>
      </sec>
      <sec id="sec-3-2">
        <title>3.2. Ontology Capture</title>
        <p>The objective of this step is to capture the domain conceptualization. In this step, concepts and relations
in a reference domain are analyzed with the consideration of a foundational ontology. Therefore, this
step requires a selection of a foundational ontology. Relevant concepts and relations are also identified
and organized, and a graphical modeling language is a key to support this. To accomplish this, we
defined our ontology in OntoUML.</p>
        <p>
          The ontology capture step has been structured around the key concepts of online career-related data,
namely (
          <xref ref-type="bibr" rid="ref1">1</xref>
          ) a person’s current employment and past job experiences, (
          <xref ref-type="bibr" rid="ref2">2</xref>
          ) a person’s active education
enrollment and graduation information, (
          <xref ref-type="bibr" rid="ref3">3</xref>
          ) skills and competences that are declared by a person and
certifications that they acquired to prove these.
        </p>
      </sec>
      <sec id="sec-3-3">
        <title>3.3. Design</title>
        <p>The design step aims to bridge the gap between conceptual modeling of reference ontologies and
operational ontology language. After a reference ontology is created, it can be transformed into an
operational ontology, which is an artifact suitable for use in computer applications. This requires the
use of a machine-readable ontology language like OWL to design and implement the ontology. In this
study, we automatically generated an OWL model from the OntoUML model using gUFO [28]. The
resulting OWL model was used in the verification phase (Section 4.4). Unlike reference ontologies,
operational ontologies prioritize computational properties above accurate representation.</p>
        <p>The remaining steps of SABiO methodology are not discussed in separate sections in the sequel for
the sake of simplification, and clarity, and due to space limitations, but are discussed together with
other issues. Implementation is discussed in Section 4, while test and the validation are discussed in
Section ?? and Section 5.</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4. Reference Ontology for Online Professional Data</title>
      <p>In this section, we discuss the ontology aspects that have been identified previously. The discussion
is separated into these aspects in order to make it more understandable. In addition, we rely on UFO
concepts and properties. We provide a brief introduction and explanation to the foundational entities
in our ontology as we introduce our modeling decisions and the UFO concepts used in these models.
Although this paper presents only graphical representations, all underlying axioms, definitions, and
types are retained and inherited as specified in UFO and implemented in OntoUML. For a more in-depth
discussion of UFO and OntoUML, we refer to [4] and related literature on OntoUML modeling principles.</p>
      <sec id="sec-4-1">
        <title>4.1. Employment and Job Experience</title>
        <p>Figure 3 shows the part of the ontology that defines a person’s job experience and models the
relationships between a person, a job position, and an employer. A person is modeled in this model as a kind,
which means that it exists on its own and maintains its identity in various contexts and time.
A solid conceptual foundation is ensured by defining a person as a kind, which captures fundamental,
immutable properties.</p>
        <p>A person can take on the roles of employee (currently employed by the organization) and former
employee (employed in the past, no longer employed by the organization), depending on their work status.
Roles are context-dependent and dynamic, meaning they exist only under specific conditions
and can change over time. A person can be an employee and a former employee simultaneously,
meaning they can be actively employed in one position while having left another, reflecting real-world
career trajectories.</p>
        <p>Similarly, an organization is also defined as a kind and can adopt the roles of employer or former
employer, depending on whether the position in question is currently active. A position is a kind,
representing a specific job in a company (Jack’s position as a Front End Developer in an organization
called SmartSys), while a position type, categorized as a type, a higher-level classification that exists
exceeding individual organizations (Front End Developer position itself).</p>
        <p>
          Three relators structure the employment relationships: (
          <xref ref-type="bibr" rid="ref1">1</xref>
          ) employment, representing the relationship
in which an employee holds a job position within an organization that employs them, (
          <xref ref-type="bibr" rid="ref2">2</xref>
          ) former
employment, representing a past relationship in which a person previously held a job position within
an organization, and (
          <xref ref-type="bibr" rid="ref3">3</xref>
          ) vacancy, representing an open job position within an organization that is
actively recruiting someone for the role. Relators encapsulate relationships between entities,
ofering a structured way to model employment interactions. Relators are linked to the relating
concepts and entities with a mediation association. Unlike approaches such as RDF properties that
model information with simple subject–predicate statements, UFO relators explicitly state multiplicity
constraints, allowing complex n-ary relationships to be specified more precisely. Mediation is a special
kind of dependency relationship connecting relators and entities that ensures the relationship
depends on the existence of its participants.
        </p>
        <p>This model also represents a snapshot of a person’s employment status. For example, after the person
move to another job, then that would become a former employment since the source of existence of
that relation changed. The new job will be the current employment since a new relationship is formed
with a new employer (and possibly a new position).</p>
      </sec>
      <sec id="sec-4-2">
        <title>4.2. Education and Graduation</title>
        <p>Figure 4 shows the part of the ontology that focuses on a person’s education and defines the relationships
between a person, the educational institution, and the academic status. A person can assume the roles
of student (currently enrolled in an educational institution) and graduate (having completed a program).
These roles can coexist, meaning a person can be a student in one institution while being a graduate
of another (or even the same) institution. The educational institution is classified as a sub-kind of
organization, distinguishing it as a specialized type of institution within the broader organizational
category.</p>
        <p>
          The relationships within this part of the ontology are structured through two relators: (
          <xref ref-type="bibr" rid="ref1">1</xref>
          ) active
enrollment, representing a current relationship in which a student is enrolled in an educational
institution, and (
          <xref ref-type="bibr" rid="ref2">2</xref>
          ) graduation, representing an educational relationship in which a person has earned a
qualification from an educational institution. This model allows for a clear diferentiation between
active enrollment and completed education.
        </p>
      </sec>
      <sec id="sec-4-3">
        <title>4.3. Skills, Competence and Certification</title>
        <p>Figure 5 shows the part of the ontology that models skills, competence, and certification, focusing on how
a person’s professional abilities are structured. Competence and skill are both modes, meaning they
are intrinsic and dispositional properties that inhere in a person. A characterization relationship
connects a person to their competence and skill, ensuring that these attributes are systematically
captured. (Characterization shows that a feature (like a skill, quality, or state) is intrinsically part of
something else and needs it to exist.) When competence and skill are formally recognized through
certification, they take on the roles of certified competence and certified skill, respectively. Additionally,
a certification provider is defined as a role, which is assumed by an organization that issues certifications.
Certification relator represents a formal qualification granted to a person by a certification provider,
recognizing specific competencies and skills.</p>
        <p>The distinction between competence, as a mode, and competence type is also critical: a competence
mode inheres in a specific person (e.g., “Bahadir’s competence in Android App Development”), whereas
a competence type represents a higher-level classification that is independent of any individual (e.g.,
“Android App Development” as a general domain of competence). This explicit modeling of certifications,
skills, and competences provides a nuanced understanding of professional expertise, addressing gaps in
previous data models.</p>
        <p>Moreover, the ontology establishes a link between competence types and position types, defining
how professional roles are associated with required skills. A position type is connected to one or
more competence types, ensuring that job roles can be analyzed based on the competences required
to perform them. Similarly, competence types are characterized by their instantiations in individuals,
meaning that a higher-level competence category is defined through its presence in people’s actual
skills. This structure enables a more systematic way to identify job roles and competences, ofering a
semantically rich and structured approach to career modeling.</p>
      </sec>
      <sec id="sec-4-4">
        <title>4.4. Ontology Verification</title>
        <p>To demonstrate the application of the proposed ontology and verify it through instantiation, we present
a practical scenario, illustrated in Figure 6. This example highlights how the ontology supports the
representation of real-world professional scenarios by connecting individuals, their competences, roles,
and institutional afiliations. John and Mary are professional aspiring the Frontend Developer career.
John has already taken a step forward in his career: he recently earned a position as a Frontend
Developer at the tech company SmartSys. In contrast, Mary is currently exploring opportunities and is
applying for a similar position at the same company. Their educational paths reflect their eforts to the
ifeld. John holds a degree in Computer Science from a renowned university, while Mary is currently
pursuing a degree in Information Systems at another renowned university.</p>
        <p>In the context of this scenario, the position of Frontend Developer at SmartSys requires a specific
type of competence: Frontend Development. So, for anyone who need to perform this position must
have competences that instantiate this competence type. As illustrated, both John and Mary possess
competences that instantiate this competence type. These shared competences qualify them to perform
the role, regardless of their current employment status. Importantly, the competences held by John
and Mary are not only aligned with the requirements of the position but are also formally recognized,
since they are certified by a Certification Provider (not depicted in 6 due to space constraints). This
certification further reinforces their suitability for the Frontend Developer role.</p>
      </sec>
    </sec>
    <sec id="sec-5">
      <title>5. Practical implications</title>
      <p>We demonstrate the practical implications of the ontology by showcasing its use in a functional
software prototype based on [ 16] that supports the career planning process of employees and job
seekers in the IT field. The system calculates the suitability of individuals to a certain position using AI
models successfully (accuracy, precision and recall all greater than 0.90), provides recommendations to
increase the suitability and shows the possible efectiveness of the recommendation with a recalculated
suitability score. Its AI component employs an ensemble learning approach, initially testing nine
diferent classification algorithms. For each case, the three best performing models were selected
to ensure optimal predictive accuracy and precision. These models were trained on a self-collected
dataset comprising anonymized career information, scraped with a self-developed Python program,
from publicly available PSMP profiles. For this study, only records related to information technology
and information systems positions were retained.</p>
      <p>The integration of the ontology was performed manually and guided the development process,
including data collection, data preparation, feature engineering, and model training. Some examples of
this are as follows.</p>
      <p>To begin with, distinction of position kind and position type inspired the job requirements to be
inferred by aggregating the shared attributes of individuals who already held that position in the real
world. This bottom-up approach of extracting requirements, rather than being defined directly or
through job postings, aims to ensure that system outputs reflect the industry realities and responds to
evidence that job postings do not always align with the actual requirements of a job position [29, 30]
(C1, C5).</p>
      <p>Next, raw data were cleaned and normalized with ontology models and look-up lists so that job titles,
skills and competencies matched the reference vocabulary. This was partly possible by integrating the
IT skills classification framework proposed by [ 31] in addition to the ontology into the training data
during feature engineering and into the structure of the recommendations. The clear definition of skill
(actionable ability such as Python programming), and competence (a broader functional ability such as
data analysis), allowed AI models to be trained with consistent and structure data (C4).</p>
      <p>In addition, the modeling of education with explicit attributes (degree level, field of study, institution,
etc.) allowed us to process education data systematically rather than relying on unstructured textual data
available on PSMPs. The data was also normalized and categorized with reference to ontology model
and reference tables for consistency. Also, the distinction between enrolled student and a graduate was
revealed with the ontology-aligned representation. Based on this, only graduation data was used to
train AI models, since enrolled student status is an ongoing process and not considered as a qualification
indicator yet (C2).</p>
      <p>Finally, the distinct separation of current and former employment revealed that the former is the
target variable and the latter is one of the variables used to predict in the AI model development (C3).</p>
      <p>Consequently, by manual integration and mapping ontology decisions to data schemas, data cleaning
scripts, feature rules, and AI model inputs, the ontology became a bridge between raw PSMP data and
the career planning system prototype. This demonstrates the ontology’s real-world applicability beyond
theoretical soundness. This process guided critical design decisions about data structure, system logic
and interface elements, thereby validating its value in the development of intelligent career planning
systems.</p>
    </sec>
    <sec id="sec-6">
      <title>6. Related Work</title>
      <p>Many available ontologies address the concepts of competence and skill. In the context of this work,
we focus on competence ontologies that consider concepts related to the reporters (certification,
employment) and positions (student, employee, employer) defined in this ontology. Similarly to this work,
some competence ontologies also consider roles related to competences, like the ontologies proposed
in [32, 33]. However, these ontologies consider generic roles related to competence, without taking
into account specific roles from the PSMP context, such as student, employer, etc. Some ontologies
address such distinctions in a way similar to this work. The ontology proposed by [34] considers the
role of employee, as well as other related concepts such as organizations (organizational entity) and
instructional entities. Acompora’s ontology [35] also considers competences (skills) related to the
employee role. However, these ontologies do not delve into such distinctions to the level realized in
this work, nor do they consider other important distinctions for PSMP. An important distinction in this
work concerns certifications that attest to competences and skills. Among the competence ontologies
considered, this distinction is not explicitly addressed. It is indirectly approached through the concept
of evidence of competence [36, 37].</p>
      <p>Most of the cited ontologies are not grounded in an ontological foundation as our work, which is
grounded in UFO. An exception in this regard is the ontology of occupations proposed in [38]. In
addition to considering concepts such as capability, ability, and skill, the authors of this ontology
also include concepts related to roles, such as occupation holder and occupation role. Nevertheless,
important concepts in the PSMP context are not considered, such as, for instance, the very concept of
competence itself. In this context, the most relevant ontology as a related work is Core-O [37], since
it also aims to propose a competence ontology by considering ontological distinctions. The ontology
proposed by [37] delves deeper into distinctions related to competence, such as skill, knowledge, attitude,
capabilities, etc. In contrast, our proposed ontology focuses more on concepts related to competence in
the professional and educational context related to PSMP, considering distinctions such as certification,
employment, enrollment, educational institution, organizations, and others, which are not considered
in Core-O.</p>
    </sec>
    <sec id="sec-7">
      <title>7. Final remarks</title>
      <p>This study proposes an ontological model for career-related personal data on PSMPs, thus enabling
semantic clarity and machine-actionable representation. The grounding of the model in the Unified
Foundational Ontology (UFO) and the implementation with OntoUML enabled this work to address some
of the main limitations and shortcomings of career-oriented data, such as the lack of conceptual clarity,
semantic interoperability, and contextual richness. In alignment with the FAIR principles (Findability,
Accessibility, Interoperability, and Reusability) [39] , we have made our ontology (psmp-ontology)
openly accessible under the permissive license via a Git repository
(https://github.com/baha-aktas/psmpontology), which hosts the complete ontology.</p>
      <p>The ontology captures critical distinctions related to employment and employment history,
education, graduation, skills, competences, and certifications, and integrates them in a way that supports
understandability and reasoning. A discussion of other competence ontologies showed that our model
introduces a more nuanced representation of roles in the context of PSMP and distinguishes between
certified and uncertified competences and skills.</p>
      <p>The practical value of ontology is also demonstrated through an example of an integration into
an AI-based career planning system. The ontology has afected key design decisions during system
development, providing the rich semantic foundation for data structuring, supporting the training of
AI models, and informing the design of the application logic (job fit calculation and recommendation
generation). By bridging the ontological modeling, PSMP data modeling and practical system design,
this work ofers a robust foundation for future applications.</p>
      <p>A potential limitation is that, although the competency questions were inspired and derived from
stakeholder interviews, they were authored by the ontologists.</p>
    </sec>
    <sec id="sec-8">
      <title>Acknowledgments</title>
      <p>This study was supported in part by The Scientific and Technological Research Council of Türkiye
(TÜBİTAK) through International Postdoctoral Research Fellowship Program.</p>
    </sec>
    <sec id="sec-9">
      <title>Declaration on Generative AI</title>
      <p>During the revision of this work the author(s) used Grammarly to check for spelling or grammatical
errors.
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