Classification Format

 

Alexander Liss

 

02/03/2009

 

 

     Classification is a basic form of scientific study, it is a simplest model. To provide Classification, one needs to outline a set of Objects of Classification, to select a set of Characteristics of the Objects and to describe how these Characteristics are “measured” in an Object from the set. Note that the “measurement” is often limited to assertion that a particular Characteristic is important in the object.

     Each Characteristic from such Classification has a set of possible Values, for example one could assert that a Characteristic C is important in the Object O and it is of a type T1 (one from a set of possible types T1,T2 and T3), or one could assert that this characteristic is not important, when one analyses this object (N/A). A set of possible Values of such Characteristic is: T1, T2, T3 and N/A (characteristic is not important).

     When one combines Characteristics, not all combinations of their Values make sense for a given set of Objects. Hence, in the Classification one has to define, which such combinations are a part of the Classification – a Class.

     The description of combinations of Values of Characteristics excluded from Classifications is a part of Classification. This part contains important information about the Objects and selected Characteristics.

     All possible combinations of possible Values of Characteristics form a set of Classes. An Object from the set of Objects could be analyzed and all appropriate Classes from the set of Classes could be selected to represent the Object.

     Objects, which have similar representation in the set of Classes (have similar sub-sets of Classes representing them), are similar. This is used in analysis of new objects and in education.

     Characteristics are often organized in a generic hierarchical form. A group of characteristics could be presented as variants of specification of another more generic Characteristic. In addition, the same Characteristic could belong to different groups and hence present specifications of different generic Characteristics.

     When one analyses an object, one selects a Hierarchy of Characteristics, takes the top of it and asks is this Characteristic important for description of the object. When it is important, one decides should be this Characteristic alone be used for Classification or it is useful to proceed with Characteristics-specifications. When this is the Characteristic is used without its further specifications, a Value is assigned to the Object. Otherwise, one looks at the next level of Characteristics and ask the same questions for each Characteristic-specification and so on. This procedure is repeated for all Hierarchies. If there are some conflicts in assignment of Values of Characteristics, because some Characteristics belong to different Hierarchies and could be measured differently, when they are applied in different points of the process, then these conflicts are resolved. In the end, a Class is assigned to the object.

A Distributed Classification is divided in relatively independent Units, where each Unit is maintained separately. In the Distributed Classification, instead of descriptions (of Characteristics, Values, Hierarchical trees, definition of Classes, etc.) references are used. Links are assigned to these references and links are updated as needed. Using these links, a proper description could be imported from a remote Unit.

     A set of Objects of Classification for a Unit is a subset of Objects of Classification of combined Classification.

As any model, the Classification evolves to reflect growing knowledge in the area and expansion of the set of objects, which it covers. Sometimes, a new Characteristic is added or a new possible Value for an existing Characteristic is added. These additions are easy to maintain.

However, sometimes one subset of Characteristics needs to be replaced with another. In such case, a new Version of the Classification is introduced. In the Distributed Classification, Units have Versions and a Version of the Classification is a set of Versions of Units.

Groups of Classes are defined through defining subsets of Characteristics and for each Characteristic from that subset a subset of Values. A Class belongs to such Group of Classes, when its definition does not contradict the definition of the Group (it could have specifications, which the Group does not have, but it cannot have specifications outside the bounds set by the Group definition).

Groups of Classes are defined using Hierarchies of Characteristics in a procedure similar to finding a Class of an Object.

When a Group of Classes is defined, the Classification could be searched and a list of Classes belonging to this group could be compiled.

     As any meaningful scientific work, designing a useful Classification is difficult, but when it exists, it provides substantial support, when one tries to find an applicable Object for a task or tries to figure out limits of applicability of a given Object.

    

     Following summarizes what is included in the Classification:

·        Description of Units of Classification (including references and links)

·        A Version of Classification (a list of Versions of Units)

·        A set of Characteristics and their possible Values (each Unit separately)

·        A set of Hierarchical trees on the set of Characteristics (using references to Units, when needed)

·        A set of Objects of Classification

·        A method of assigning a Value of Characteristic for each Object (in a Unit, where the Characteristic is defined)

·        A set of combinations of Values of Characteristics excluded from Classification (each Unit separately)

·        A (partial) list of Classes with Values of Characteristics, which define them and examples of Objects, which belong to them

 

 

 

Formal Description

 

     Following provides elements of Formal Description of the Classification, which allow automated searches through Classification and sharing of information between Units. All is encoded in XML; names of nodes are in brackets.

 

Distributed Classification Head [head]

 

     Each Classification Unit provides its name [name], information about its Version [version], and description of other Units [units].

     The description of a remote Unit [unit] includes:

 

List of Characteristics [factors]

 

     Description of each Characteristic [factor] includes its name [name], description [description], description of ways to assign a Value to an Object of Classification according to this Characteristic [measurement] and a list of possible Values [values], where each Value [value] has a name [name] and description [description].

 

List of Hierarchies [hierarchies]

 

     Description of each hierarchy [hierarchy] contains its name [name] and a description [description] of a tree, which is convenient to describe using XML. It is described with nodes [nodes], where each node [node] contains a name of Characteristic and a list of child nodes. Each node could contain description [description] describing how its Characteristic relates to the Characteristic of the parent node.

 

 

Description of Objects of Classification [objects]

 

     This part is a free form description of Objects of Classification

 

 

Excluded Combinations [excluded]

 

     It is a list of Group of Classes of Objects, where each element of the list [group] contains description of the group [description] and a list [limits] of combinations [limit] of Characteristic’s name [name] and ranges of Values [ranges], where an element of this list [range] contains either a Value  or a range of Values of given Characteristic.

 

Classes [classes]

 

     A Class [class] (an element of the list of Classes) contains a list of Characteristics and their Values, which define it [definition], where each element of this list [unit] contains a name (reference name, in case of remotely defined Characteristic) [name] and a Value [value]. In addition, it contains a URL link [link] to the Class description, examples of Objects and their use. These descriptions are perpetually updated; hence they are kept in a separate place.

 

 

Querying the Classification

 

     A request is description of a Group of Objects of Classification. The response to such request is a list of Classes. Both are encoded with XML.

 

Request [request]

 

     It is a list of combinations [limits] of Characteristic’s name [name] and ranges of Values [ranges], where an element of this list [range] contains either a Value or a range of Values of given Characteristic.

 

Response [response]

 

     It is a list of Classes, where each element of the list [class] contains a list of Characteristics and their Values, which define it [definition], where each element [unit] contains a name (reference name, in case of remotely defined Characteristic) [name] and a Value [value]. In addition, it contains a URL link [link] to the Class description.

 

Secondary Query

 

     Classes are associated with Objects 9lists of references, for example). Secondary Query retrieves lists of these Objects.

 

Graphical User Interface

 

     Querying of the Classification is supported with GUI.

     Entire Classification is presented in a way reminiscent of a file explorer, where nodes of Hierarchies (Characteristics) correspond to directories (with the difference that there are duplicate nodes in such presentation). These nodes could be expended or collapsed with a mouse click. Each node “directory” contains a “file”, clicking on which opens GIU module describing available Values of the Characteristic and providing ability to select a subset of Values.

     When all selections are done, the check of selection consistency could be initiated and query into the Classification could be submitted.

     The result is presented as an HTML page with links to descriptions of Classes.

     Broken links to other Units lead simply to large number of truncated hierarchies.

     If a Secondary Query is involved, then it is executed using a list of Classes and presented according to the nature of the presentation of lists of Objects.

 

 

 

 

 

 

Examples

 

1. Classification Unit of Properties of Parameters of a Model and Results of their Measurement

 

<head>

     <name>

properties of parameters and results of their measurement

     <name>

     <version>

     1

     <version>

</head>

 

<factors>

<factor>

     <name>

          type of parameter

     </name>

     <description>

In The Art of Optimization (see this site) parameters of models are divided into three types, the type of parameters used affects what kind of conclusion could be made using the model

     </description>

     <measurement>

A parameter of the model is assigned its type according to procedure described in The Art of Optimization

     </measurement>

     <values>

          <value>

              <name>

                   technical

              </name>

              <description>

Parameters like length, weight, time, fuel efficiency, etc.

              </description>

          </value>

<value>

              <name>

                   money based

              </name>

Parameters like cost, price, interest rate, etc.

              <description>

              </description>

          </value>

     <value>

              <name>

                   conventional

              </name>

              <description>

Parameters like “acceptance of risk”, “warmth of color, etc.

              </description>

          </value>

     </values>

</factor>

 

<factor>

     <name>

          type of result of measurement

     </name>

     <description>

The type defines what kind of operations could be performed with results of measurement, see The Art of Optimization

     </description>

     <measurement>

Type of the results of measurement of a parameter is a well known characteristic of measurement; it is specified together with measurement procedure

     </measurement>

     <values>

          <value>

              <name>

                   order

              </name>

              <description>

Only an order of results of measurement is meaningful, (hardness)

              </description>

          </value>

<value>

              <name>

                   difference

              </name>

              <description>

Difference between Values (and, hence, order of values) is meaningful (temperature)

              </description>

          </value>

     <value>

              <name>

                   ratio

              </name>

              <description>

Ratio of Values (and, hence, difference between Values and order of Values) is meaningful (mass, volume)

              </description>

          </value>

     </values>

</factor>

 

<factor>

     <name>

          sources of information

     </name>

     <description>

This is an indirect way of assessing quality of data used to arrive to results of measurements of parameters of the model

     </description>

</factor>

</factors>

 

<excluded>

     <group>

          <description>

Results of measurement of money based parameters are of type “ratio”

          </description>

          <limits>

<limit>

          <name>

              type of parameter

          </name>

          <ranges>

                   <range>

                        money based

                   </range>

</ranges>

          </limit>

 

          <limit>

          <name>

              type of result of measurement

          </name>

              <ranges>

<range>

                        order, difference

                   </range>

              </ranges>

          </limit>

          </limits>

     </group>

</excluded>

 

<classes>

 

<class>

     <definition>

 

<unit>

              <name>

                   type of parameter

</name>

<value>

          technical

</value>

</unit>

 

<unit>

              <name>

                   type of result of measurement

</name>

<value>

          order

</value>

</unit>

          </definition>

</class>

 

<class>

     <definition>

 

<unit>

              <name>

                   type of parameter

</name>

<value>

          technical

</value>

</unit>

 

<unit>

              <name>

                   type of result of measurement

</name>

<value>

          difference

</value>

</unit>

          </definition>

</class>

 

<class>

     <definition>

 

<unit>

              <name>

                   type of parameter

</name>

<value>

          technical

</value>

</unit>

 

<unit>

              <name>

                   type of result of measurement

</name>

<value>

          ratio

</value>

</unit>

          </definition>

</class>

 

<class>

     <definition>

 

<unit>

              <name>

                   type of parameter

</name>

<value>

          money based

</value>

</unit>

 

<unit>

              <name>

                   type of result of measurement

</name>

<value>

          ratio

</value>

</unit>

          </definition>

</class>

 

 

<class>

     <definition>

 

<unit>

              <name>

                   type of parameter

</name>

<value>

          conventional

</value>

</unit>

 

<unit>

              <name>

                   type of result of measurement

</name>

<value>

          order

</value>

</unit>

          </definition>

</class>

 

<class>

     <definition>

 

<unit>

              <name>

                   type of parameter

</name>

<value>

          conventional

</value>

</unit>

 

<unit>

              <name>

                   type of result of measurement

</name>

<value>

          difference

</value>

</unit>

          </definition>

</class>

 

<class>

     <definition>

 

<unit>

              <name>

                   type of parameter

</name>

<value>

          conventional

</value>

</unit>

 

<unit>

              <name>

                   type of result of measurement

</name>

<value>

          ratio

</value>

</unit>

          </definition>

</class>

 

</classes>

 

 

 

 

 

 

 

2. Description of Hierarchy of Characteristics

 

<hierarchies>

 

  <hierarchy>

 

     <name>

          description of the object’s functioning

     </name>

 

     <description>

Functioning of objects of optimization could be described in more or less formal and detailed way or could be inferred from experimentations with the object (see The Art of Optimization)

     </description>

 

     <node>

          <name>

              description of the object’s functioning

          </name>

 

     <node>

          <name>

               structure of the object

          <name>

<node>

              <name>

                   number of elements

              <name>

          </node>

<node>

              <name>

type of connections between  elements

              <name>

          </node>

     </node>

 

<node>

          <name>

              source of information

          <name>

     </node>

 

 

 

<node>

          <name>

              macro models used

          <name>

 

<node>

              <name>

type of theory used to make the model

              <name>

          </node>

     </node>

     </node>

  </hierarchy>

</hierarchies>