Presenting notation-building rules. Each classification implements certain rules for building notations. The following are some typical examples. 1) In current authority systems there are always records indicating how a notation should be composed or de-composed. 2) A synthesized number can be constructed by adding or appending numbers from a table or from other parts of the schedule. Instructions are provided to the classifier to construct a classification number by adding numbers from other parts of the schedule, from a table, or by basing it on a pattern defined in another part of the schedule. 3) Depending on the degree of synthesized components, some classification schemes have a variety of faceted structures for their main schedules, sub-schedules, or individual classes. Rules and instruction guidance are always included in such cases. 4) There could be full, abridged, and extended (+) notations for the derivations from a general classification system. Unlike a thesaurus, a classification system usually develops variations of a scheme with different scales. Implementers decide to which degree they want to implement it in practice. For example, in CLC's ‘062.32+6’ the number after ‘+’ is the optional, extended number with higher specificity.
The intersection of two classes consists of exactly those individuals which are instances of both classes. The following example states that the class Mother consists of exactly those objects which are instances of both Woman and Parent: EquivalentClasses( :Mother ObjectIntersectionOf( :Woman :Parent ) ) In Functional-Style Syntax
General works on cardiac rehabilitation are classed in 616.1203 Heart diseases—rehabilitation (built with 616.12 Diseases of heart plus 03 Rehabilitation from the add table under 616.1–616.9 Specific diseases , following the add footnote at 616.12 : “Add as instructed under 616.1–616.9”). Examples of works classed in 616.1203 are Cardiac Rehabilitation: A Guide to Practice in the 21st Century and Cardiac Rehabilitation . http://ddc.typepad.com/025431/600699_technology/ Number Building: The process of constructing a number by adding notation from the tables or other parts of the schedules to a base number Add note A note instructing the classifier to append digits found elsewhere in the DDC to a given base number. In Functional-Style Syntax
Restrictions describe a class of individuals based on the type and possibly number of relationships that they participate in. - Restrictions can be grouped into three main categories: Quantifier Restrictions ( Existential ∃ , Universal ∀) - Cardinality Restrictions (Min ≥, Equal =, Max ≤) Has Value Restriction (∍) These symbols are from descriptive logic. We will not get into these, but will have an example of existential restriction.
Expressing Classification Schemes -- Part 3
Expressing Classification Schemes with OWL 2 Web Ontology Language