1. No texto sobre Ontologia [Model Driven …] às fls. 47 o autor afirma
“Another important issue here is the distinction between ontological
knowledge and all other types of knowledge, illustrated in Table 1-1 [see
TelEduc Table 1-1]. An ontology represents the fundamental knowledge
about a topic of interest; it is possible for much of the other knowledge about
the same topic to grow around the ontology, referring to it, but representing
a whole in itself.” Explique e comente esta afirmação
When we speak of Ontologies as "knowledge representation systems" must
specify what type of system we mean. Ontologies are being used in all types of
applications in which it is necessary to define precisely the set of relevant in the
particular field of applications entities and interactions between them. Some
ontologies are created with the simple goal of reaching an understanding. Others
ontologies have been created with a general purpose.
Ontological knowledge describes the categories of things in that domain and the
terms that people use to talk about them. For example, the ontological knowledge
about an object-oriented language contains the concept of a class. Ontological
knowledge also describes relations between such concepts, and the axioms and
constraints in the domain.
Procedural knowledge is about how to do something, for example how a problem
is solved. Some typical types of knowledge in this category are rules, problemsolving strategies, agendas and procedures.
Declarative knowledge describes what is known about a topic or about a
problem. For example, some statements of declarative knowledge may describe
details of concepts and objects. Some other statements may express facts that are
either true or false.
Metaknowledge is knowledge about knowledge. It is used to decide what other
knowledge is best suited for solving the problem at hand, what other knowledge is
irrelevant to the problem and should therefore not be considered at all.
Heuristic knowledge includes those rules of thumb that guide the problem-solving
process on the basis of previous experience in solving problems, individual intuition
and skills, and a good understanding of the problem.
Structural knowledge describes mental models and the organization of problems,
solutions, and their respective spaces.
Inexact and uncertain knowledge characterizes problems, topics, and situations
in which information is inherently imprecise, unavailable, incomplete, random, or
ambiguous.
Commonsense knowledge is the term used to denote a vast amount of human
knowledge about the world which cannot be put easily in the form of precise
theories.
2. Considere o exemplo sobre RDF apresentado às fls 45-46 do livro texto.
Compare este exemplo definido via RDF e via UML (Slide 13).
Plain-English RDF Schema
Class: Fungi
Definition: Contains all fungi
Subclass of: Class Opisthokonta (described in another RDF Schema)
Class: Plantae
Definition: Includes multicellular organisms such as flowering plants, conifers, ferns, and mosses
Subclass of: Class Archaeplastida (described in another RDF Schema)
Property: Stationary existence
Definition: Adult organism does not ambulate under its own power
Range of classes: Class Fungi, Class Plantae
Property: Soil habitation
Definition: Lives in soil
Range of classes: Class Fungi, Class Plantae
Property: Chitinous cell wall
Definition: Chitin is an extracellular material often forming part of the matrix surrounding cells
Range of classes: Class Opisthokonta
Property: Cellulosic cell wall
Definition: Cellulose is an extracellular material often forming part of the matrix surrounding cells
Range of classes: Class Archaeplastida
Here I made the UML representation of example (pages 45, 46) in RDF.
UML class diagrams provide a static modelling capability that is well suited for
representing ontologies.
RDF is a simple resource-property-value model designed for expressing metadata
about resources on the Web.
Web Ontology Language (OWL) is a semantic markup language (XMLbased) for
publishing and sharing ontologies on the World Wide Web, which provides a
vocabulary to represent classes, classes hierarchies, associations between
classes and properties, therefore suitable to represent UML models. The OWL has
been developed based on XML, RDF and RDF Schema [11] technologies;
however it provides a richer vocabulary than RDF for describing properties and
classes.