Knowledge Classes or Canonical Representation
My approach to deal with the multiple-domain / multiple source problem in building knowledge bases is to establish a non-ambiguous, mutually exclusive classification of different types of knowledge, in other words, a canonical representation. The rationale is that by encapsulating each and all knowledge units in one of these categories, we create a virtual level of knowledge representation where the dominant traits are not domain-dependent, since we can define them at a syntactic level, instead of a semantic level.
This canonical representation was achieved by reviewing a large set of multi-domain vocabulary (more than one thousand items) and several field taxonomies (from different school curricula, job market demand and supply on domain qualifications, etc.). As a result, I identified the following categories: Term; Concept; Definition; Model; Rule; Norm; Procedure; Methodology; Description.
Term:
Short word or sentence ;
Represents an element of technical, scientific or cultural vocabulary; or a variable in an algebraic expression;
May be defined in a simpler and less technical language (Glossary);
Does not require extensive explanations or complex theoretical foundation;
Definition may contain other terms only .
Concept:
Word or sentence ;
Represents an idea or abstraction (technical, scientific or cultural), or a knowledge domain (class, sub-class, domain);
May be explained in lay language, eventually requiring more or less complex theoretical foundation;
Explanation may contain terms or other concepts, of similar or lesser complexity.
Definition:
One or more sentences;
Represents the exact, non ambiguous explanation of a term or concept; or establishes an axiom, which should, in this case, be considered a term or concept;
There may be more than one definition per concept, and they may or not contradict themselves (if they do, it implies the co-existance of several truth/belief systems);
Explanation may contain other terms and concepts, other than the object being defined, of similar or lesser complexity.
Model:
One or more algebraic expressions (set of variables linked by algebraic or logical operators );
May establish an axiom ( variables must also be considered terms).
Rule:
Regular expression [IF precedent THEN consequent], in which precedent and consequent are a set of one or more conditions linked by the logical operator AND, where condition is a 3-tuple variable-operator algebraic-value;
Represents a causal or dependency relationship between phenomena, identified through investigation and not arbitrarly set.
Norm:
Regular expression [IF precedent THEN consequent], in which precedent and consequent are a set of one or more conditions linked by the logical operator AND, where condition is a 3-tuple variable-operator algebraic-value, and the consequent part may be a set of conditions or a set of procedures;
Represents a causal relationship resultant from arbitrary determination.
Procedure:
One or more phrases or images;
Represents a sequence of one or more acts ( operations, interventions ) of one or more agents acting on one or more target-objects (people, things, entities, etc.);
Is conditioned by rules or norms.
Methodology:
Set of norms and procedures.
Description:
One or more phrases, images or sounds;
Factually represents things, people, entities, places, events, situations or states ;
May contain models, terms, concepts and other descriptions.