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gellish_databases

1. Universal Semantic Databases

Gellish is a universally applicable language. This enables to define universal databases, provided that we can define a universal syntax or data model. This is indeed possible on the basis of the universal basic semantic structures that are described elsewhere.
A Gellish Universal Semantic Database or Gellish Data Exchange Message consists of a collection of Gellish Expressions with a uniform structure as briefly described in this section.
Every Gellish expression is an expression of a 'main fact' (a main statement or proposition or query) and a number of 'accessory facts' that are relevant for the correct interpretation of the main fact. Together, the accessory facts form the “Gellish set of kinds of accessory facts ”. The set is comparable with the 'Dublin core'. The Gellish set is intended to be a complete set of kinds of accessory facts that are dedicated to an expression of one fact and do not imply additional main facts.

The structure or syntax of Gellish expressions is also universally applicable and does not require a dedicated data model, nor a dedicated database design. Gellish expressions can be implemented in a simple syntax that consists of the structure of one universal Gellish Expression Table, whereas that table structure can be presented in various different forms, such as flat Unicode files, Excel spreadsheet tables, SQL tables or RDF/XML triple stores. Each Gellish Database consists of one or more Gellish Expression Tables. Each of those tables has basically the same structure. and is standardised and is application system independent. This is different from conventional databases that usually have proprietary data structures, and that have database tables that are all different. Each of the Gellish Database tables shall contain at least the obligatory columns of one of the subsets of columns that are defined in the Gellish Database Definition document, which is summarised below.
The content of Gellish Expression Tables shall be compliant with the grammar and the dictionary of the Gellish Formal English language (or a Gellish variant in any other natural language). The standardized tables, combined with the Gellish formal language and its management of unique identifiers ensures that the content of various tables can be combined and used as an integrated set without the need for data harmonization or conversion. This enables to combine an arbitrary number of Gellish Expression Tables into one (virtual) Database. Furthermore, such a database might be centralised, but it can also be a distributed database. The consistency of the various tables can be verified by software. Furthermore it enables that a Gellish query can be executed on each independent Expression Table, whereas the results of the query can be combined and presented together to a user. This means that the tables then act as a distributed database.
The various Gellish Expression Tables all have the same column definitions. Apart from the fact that tables may use a subset table when appropriate. Preferred collections of columns are defined in standard Gellish Expression Table subsets.

A Gellish Database with Gellish Expression Tables may be implemented in various formats. It can be in the form of an SQL database, or in XML, or even in XLS (the form of Excel spreadsheet tables), but the tables may also be converted into non-tabular implementation forms, such as in RDF/XML.

2. Limitations of conventional databases

Conventional databases typically consist of many tables, each of which is composed of a number of columns. The definition of those tables and columns determine the storage capabilities of the database, whereas the relations between the columns define the kinds of facts that can be stored in such a database. Those columns and relations determine the database structure that defines the expression capabilities of the database. Similar rules apply for the structure of data exchange files and thus for the information that is exchanged in electronic data files.
This conventional database technology has some major constraints:

  • When data was not covered during the database design and thus is not included in the data model, then such data cannot be stored in the database nor exchanged via such a data file structure.
  • Different databases have different data structures, which causes that data in one database cannot be integrated with data from other databases nor exchanged between databases without dedicated data conversion.
  • A database modification or extension requires redesign of the database structure, modification of software and data conversion, which makes it a relatively complicated and costly exercise.

Another characteristic of conventional databases is that there are hardy international standards available or used for the content of the databases, being the data that is entered by its users. This typically means that local conventions are applied to limit the diversity of data that may be entered in those databases. As local conventions usually differ from other local conventions this has as disadvantage that data that are entered in one database cannot be compared or integrated with data in other databases, even if those database structures are the same and even if the application domain of the databases is the same. For example, within a company there may be various implementations of the same system in various sites for the storage of data about equipment, whereas for example the performance data about the same type of equipment still cannot be compared with the performance data in another location, because the equipment types have different names and the properties are also different.

3. Characteristics of a Gellish Database

A Gellish database does not have the semantic limitations that conventional databases have, because of the flexibility and openness of the Gellish language and because of its standard universal data structure (syntax), which is simple and computer as well as human interpretable.
A Gellish database consists of one or more database tables, each of which has the same Gellish Expression Table structure (with standard column definitions). The fact that those Gellish Expression Tables are standardised and universally applicable makes a Gellish database application independent. A standardised Gellish Expression Table is universally applicable because it enables the application of the following fundamental principles:

  1. Explicit classification and specialization relations.
    Explicit classification of individual things or explicit specialisation of kinds of things (concepts, classes and types), with an unlimited number of kinds of things in a dictionary.
  2. Unlimited extendability, formal and open.
    The Gellish Expression Table enables to store any kind of statement about any kind of object; because any individual object can be introduced by specification of an explicit classification relation between the object and a kind of thing, whereas kinds of things can be selected from an unlimited combined closed and open dictionary. The dictionary has a core of generic concepts. This core can be used in combination with the existing large Gellish Formal English Dictionary-Taxonomy (or a subset of that) or it can be combined with a proprietary or public extension of it. This flexibility is fundamentally different from conventional databases that predefine the object types (classes) about which information can be stored by defining a limited number of entity types and attribute types in a fixed data model.
  3. Unlimited semantic expression capability.
    The semantic expression capability is provided by explicit classification of relations (expressions of facts), by an extensible unlimited number of standardized relation types.
  4. Powerful standard Gellish set of accessory facts.
    The Gellish Expression Table enables to store any kind of statement about any kind of object, because any fact can be expressed by a relation, whereas those relations are explicitly classified by relation types that can be selected from the standardised collection of relation types that are defined in the Gellish Dictionary-Taxonomy or by relation types that are added to the dictionary as proprietary extensions. This flexibility is also fundamentally different from conventional databases that predefine a fixed and limited number of relation types between the columns in the database tables (whereas unfortunately those relation types are usually defined only in an implicit way).

As a consequence, a Gellish database does not need to be modified or extended when the scope of an application changes and facts from different Gellish databases can be merged and integrated whenever required without a need for a conversion exercise. Furthermore the content of a Gellish Database uses a common Gellish Dictionary-Taxonomy for all its data, including for example, kinds of equipment, kinds of properties, kinds of documents, kinds of activities, etc., etc.

3.1 Gellish Expressions in a Gellish Database

A Gellish Database is a database that contains one or more standardized Gellish Expression Tables. Each such table contains the same predefined columns and is suitable for the expression of virtually any kind of fact such that is computer interpretable and system independent. The table can be implemented as an MSAccess database table, an SQL database table or simply as a standard table in a spreadsheet. The core of a Gellish Database table consists of three columns, just as is the case in RDF/Notation 3. Each row with those three columns in such a table expresses a main (binary) fact. For example, the fact that the Eiffel tower is located in Paris can be expressed as follows:

Left hand object Relation type Right hand object
The Eiffel tower is located in Paris
The Eiffel tower is classified as a tower
Paris is classified as a city

The left hand objects and the right hand objects may either be selected from the Gellish English dictionary or may be new proprietary objects that are introduced by defining them on separate lines. If such a new object is an individual thing, then it shall be defined by a classification relation with a class, as is done in the above table and if the nwe object is a class, then it shall be defined on a separate line by a specialisation relation with their direct supertype. The relation types (such as 'is located in' and 'is classified as a') shall be selected from the Gellish English dictionary, otherwise the expression cannot be called standard Gellish, but becomes a proprietary extension of Gellish English.

3.2 Multi-language support

Furthermore, a Gellish database structure supports the simultaneous use of multiple languages. This is enabled because a Gellish database table contains a separate column for the language in which a fact is expressed (see the example table below). Thus a Gellish database supports the use of various natural language specific versions of Gellish. In principle, there is a Gellish variant language for each natural language, depending on the availability of a translation of the Gellish concepts. For example, the Gellish English Dictionary defines Gellish English, and contains partial translations to Gellish Deutsch (German) and Gellish Nederlands (Dutch). International terminology (such as most units of measure and mathematical concepts) is included as International Gellish.

3.3 Unique identifiers, homonyms, synonyms and automatic translation

A Gellish database uses a unique identifier for each thing, irrespective whether it is a user object, a concept from the Gellish dictionary, a fact or a relation type. The following Gellish database table is an extended version of the above example and includes the language in which the fact is expressed as well as the identifiers of the objects.

Language UID of left hand objet Name of left hand object UID of fact UID of relation type Name of relation type UID of right hand object Name of right hand object
English 1 The Eiffel tower 101 5138 is located in 2700887 Paris
English 1 The Eiffel tower 102 1225 is classified as a 40903 tower
Dutch 1 De Eiffel toren 103 4691 is a translation of 1 The Eiffel tower

The unique identifiers enable the use of synonyms and homonyms and enable that a computer can automatically translate a Gellish expression in a certain language into a Gellish expression in another language. This is caused by the fact that the meaning of a Gellish expression is captured as a relation between the unique identifiers, so that the meaning is language independent.
This adds automatic translation capabilities to Gellish expressions, because a Gellish message can be created e.g. in Gellish English whereas computer software can present it in another Gellish variant, such as Gellish Dutch if a dictionary or a translation is available, such as on the third line in the above table.

3.4 Accessory facts

A Gellish Expression Table has a number of additional columns that enable the expression of accessory facts or data about the main facts. For example, columns for:

  • a textual definition in natural language of the left hand object
  • the context in which the fact is valid
  • a unit of measure with its UID
  • the status of the fact (accepted, proposed, deleted, replaced, etc.)
  • the originator of the fact
  • the date of creation of the fact
  • etc.

These accessory facts are described in more detail in the next chapter.

4. Gellish Expression Table Definition

The document 'Definition of Universal Semantic Databases and Data Exchange Messages ' defines the full set of columns in each Gellish Expression Table that is part of a Gellish Database, a Gellish Message or a Gellish Query. The document also defines a number of standardized subsets for usage in applications that do not require the full number of columns.
One of those subsets, the Business Model subset, is suitable for nearly all database contents data exchange usecases that describe knowledge and propositions. It application range includes business communication about both designs (imaginary objects) as well as real world objects (observed individual objects) during their lifecycle and about enquiries, answers, orders, confirmations, etc. This table is a superset (indicated in bold) of the product model table, so it can also be used for knowledge about classes of objects.
This subset consists of over 30 standard table columns.

As sumary of the above document is given below.

4.1 The Gellish Expression Table header definition

Each Gellish Expression Table has in principle a table header that defines the columns in the table and a table body with a row for each expression of a main fact and its accessory facts.
A Gellish Expression Table can consist either of a complete set of columns or of a subset of columns. The document defines a number of standard subsets.
Each column has a column ID and a column name and has a meaning as defined below.
Note that the presence of a value in a column field implies one or more relations with values in other columns. The semantics of these implied relations are specified in the definitions of the table columns. Those relations define the (accessory) facts about the main fact!

If the table is implemented in a spreadsheet or ASCII or Unicode file, then the table starts with a header of three lines, as follows:

  • The first line contains a sequence of the following four fields A1, A2, A3 and A4, which shall contain the following text:

A1 = ’Gellish’
A2 = Natural language of the expressions in the table. Default 'Formal English'.
A3 = ‘Version:’
A4 = version number of the applicable Gellish dictionary.
A5 = date of the release of the facts in this table (optional).
followed by free text fields.

  • The second line contains the column ID’s which consists of standard numbers, although arbitrarily chosen. They allow the columns to be presented in a different sequence without loss of meaning (the numbers below correspond to those column ID’s).
  • The third line contains human readable text in every column field providing a short name of the column. This name is free text.

4.2 The Gellish Expression Table body column definitions

The lines (rows) in a Gellish Expression Table are independent of each other and thus the lines may be sorted in any sequence, without loss of semantics (meaning).

Each line in the body of a Gellish Expression Table (which in a spreadsheet starts on the fourth line) expresses a group of facts, which consists of a 'main fact' and a number of 'accessory facts' that aredefined as follows.

Main fact.
A main fact is expressed by a combination of the following objects (the column IDs' are given in brackets):

  • A UID of a main fact (1)
  • A UID of a left hand object (2)
  • A UID of a relation type (60)
  • A UID of a right hand object (15)
  • A UID of a scale (unit of measure) (66)
  • A UID of an intention (5)

Prime accessory facts.

The prime accessory facts are represented by the following table columns, each of which implies an expression by a triple of objects (which are implicitly classificied). The table columns are:

  • A UID of a left hand kind of role (72)
  • A UID of a right hand kind of role (74)
  • A pair of left hand object cardinalities (44)
  • A pair of right hand object cardinalities (45)
  • A UID of the accuracy of a quantification (76)
  • A UID of a pick list for the qualification of aspects (70)
  • A UID of the validity context for a fact (19)
  • A partial textual definition of a concept or individual thing (65)
  • A full textual definition of a concept or individual thing (4)
  • A textual description of a main fact (42)
  • Remarks on the expression of a main fact (14)
  • Approval status of the expression of a main fact (8)

Secondary accessory facts.

The secondary accessory facts are represented by the following table columns, each of which implies a triple of classified objects. These accessory facts form the context for the validity of the UID’s and the names for objects that are identified by their UID’s:

  • A reason for latest change of status
  • A UID of the successor of the fact, in cases it has the status 'replaced'
  • UID of creator of fact
  • Date-time of start of validity of the fact
  • Date-time of start of availability of the expression
  • Date-time of creation of copy
  • Date-time of latest change of the expression
  • UID of addressee of the expression
  • References
  • UID of the expression of the fact (Line UID)
  • UID of a collection of facts to which the fact belongs
  • A presentation sequence in which the expressions can be presented

The columns with UID's are accompanied by columns with a name for the thing that is represented by the UID.

Field formats and optionality

Several columns contain unique identifiers (UID’s). Each UID should preferably be represented by a 64-bit integer (8-byte, Int64 or bigint'),' whereas only positive values shall be used. It is not recommended to use an unsigned integer (which only allows positive values) because SQL only enables the bigint datatype, which is signed.
Most other columns contain character string values. For database implementations it is indicated whether they have a fixed or variable length (nvarchar or varchar) or whether the string is externally stored (data types ntext and text). In addition to that it is indicated whether the cells may contain Unicode.
Fields in columns that are indicated as optional may be left empty, in which case the indicated default value is applicable. Otherwise a field value is obligatory.

Further details of the column definitions are given in the document 'Definition of Universal Semantic Databases and Data Exchange Messages '

Continue with 1. Domain Dictionaries and Dictionary Extensions

[1]See http://support.microsoft.com/kb/q180162/


gellish_databases.txt · Last modified: 2017/08/11 15:10 (external edit)