Object Properties
==================

Object properties relate one entity to another (not one class to another) [Harmse2018]_. 
For example, an organization may be 
"part of" another organization.  "part of" is an object property that describes the 
relations between the two individual organizations.

|BFO| uses the 
`Relation Ontology (RO) <http://www.ontobee.org/ontology/RO>`_ to define object 
properties.

Each object property can have a domain and a range.  When we say property p has domain D,
we mean that all triples of the form x P y, x is a D.  When we say property p has range R,
we mean that in all triples of the form x P y, y is an R.

For example, if we define an object property "author_of", we might define the domain to
be "Person" and the range to be "Information Content Entity". If we write x author_of y,
we know x is a Person and y is an Information Content Entity. [#]_



Common Object Properties
------------------------

Some object properties are quite common in the representation of scholarship.  Many
representations involve the use of identifiers.  People, publications, organizations
and other entities may be "denoted_by" an identifier.  We assert, for example,::

    x a Person
    y a ORCID
    x denoted_by y
    
"denoted_by" has an *inverse property* "denotes."  If x is denoted_by y, then y denotes x.
We could write the above as::

    x a Person
    y a ORCID
    y denotes x

See :ref:`Table 16`. The pattern *entity1 bearer_of role; role realized_in process; 
process
has_output entity2* is quite common and describes the role entity1 had through a process 
in
the creation of entity2. Each of these properties has an inverse, so we could assert
equivalently, *entity2 output_of process; process realizes role; role inheres in entity1*. 

.. _Table 16:

.. table:: Table 16 Common Object Properties

    ===============  =======================  ================================================
    Property         Label                    Notes
    ===============  =======================  ================================================
    ``BFO_0000050``  part of                  An entity is part of another entity
    ``BFO_0000051``  has part                 Inverse of part of
    ``IAO_0000219``  denotes                  The relation between an identifier and entity
    ``IAO_0000235``  denoted by               Inverse of denotes
    ``RO_0000053``   bearer of                relation between a dependent and its bearer
    ``RO_0000052``   inheres in               The inverse of bearer of
    ``BFO_0000055``  realizes                 A process realizes a role
    ``BFO_0000054``  realized in              A role is realized in a process
    ``RO_0002234``   has output               An occurrent has a continuant as an output
    ``RO_0002353``   output of                A continuant is the output of an occurrent
    ``RO_0000086``   has quality              An entity has another entity as a quality
    ``RO_0000080``   quality of               An entity is a quality of another entity
    ===============  =======================  ================================================

All Object Properties
-----------------------

.. include:: tab-all-object-properties.txt

.. include:: toc-ObjectProperty.txt



.. [Harmse2018] Harmse, Henrietta, A Common Misconception regarding OWL Properties,
    blog post, 
    https://henrietteharmse.com/2018/06/22/a-common-misconception-regarding-owl-properties/ 
    
.. rubric:: Footnotes

.. [#] Are these the correct domain and range for such a property? Discuss.

.. We will have a script that can read the ontology and write documentation pages, one per
   property.  The property pages will be listed in a toctree directive generated by the 
   script 
   and included here.  In this way, we make sure all the properties are documented and 
   that
   the document for each is generated automatically from the ontology.