Gellish database

Gellish Databases

Each Gellish Database consists of one or more Gellish Database tables. Each of those Gellish Database 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, whereas all database tables are different. Each of the Gellish Database tables shall contain at least the obligatory columns that are defined in Gellish Database Definition document.

The content of Gellish Database tables shall be compliant with the grammar and the dictionary of the formal Gellish English language (or a Gellish variant in any other natural language). The standardised tables, combined with the formal Gellish language enables to combine an arbitrary number of Gellish Database tables into one Database. Furthermore, such a database might be centralised, but can also be a distributed database. This also enables to combine the results of a query to various independent data stores, which then act as a distributed database.

The various Gellish Database tables all have the same core of column definitions. Apart from that core, the tables may also have one or more of the optional columns. Preferred collections of columns are defined in standard Gellish database table subsets.

A Gellish Database 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).

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.

Characteristics of a Gellish Database

A Gellish database does not have the semantic limitations that conventional databases have, because of the flexible and open Gellish language and because of its standard universal data structure (grammar), which is simple, computer and human interpretable. A Gellish database consists of one or more database tables, each of which has the same table structure (column definitions). The fact that those Gellish Database tables are standardised and universally applicable makes a Gellish database application independent. A standardised Gellish database table is universally applicable because it enables the application of the following two fundamental principles:

Explicit classification of individual things or explicit specialisation of classes, with an unlimited number of classes in a dictionary.The Gellish database table enables to store any kind of object; because any individual object can be introduced by specification of an explicit classification relation between the object and a class, whereas classes (kinds of objects or concepts) can be selected from the very large number of classes that are already defined in the Gellish English Dictionary and if the proper class is not available it can be added by specification of a subtype-supertype relation with a direct supertype of the new class. This 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.

Explicit classification of relations (facts), by an extensible unlimited number of standardised relation types.The Gellish database table enables to store any kind of fact about any kind of object, because any fact is expressed by a relation, whereas those relations are explicitly classified by relation types that can be selected from the standardised relation types that are defined in the Gellish Dictionary or by relation types that are added to the dictionary as proprietary extensions. This is 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 for all its data, including for example, equipment types, property types, document types, activity types, etc.

Gellish Expressions in a Gellish Database

A Gellish Database is a database that contains one or more standardised Gellish Database 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:

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.

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.

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 objectEnglish 1 The Eiffel tower 101 5138 is located in 2700887 ParisEnglish 1 The Eiffel tower 102 1225 is classified as a 40903 towerDutch 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.

Auxiliary facts

A full Gellish database table has a number of additional columns that enable the expression of auxiliary facts or data about the main facts. For example, columns for:

a textual definition of the left hand objectthe context in which a fact is valida unit of measure with its UIDthe status of the fact (accepted, proposed, deleted, replaced, etc.)the originator of the factthe date of creation of the factetc.

Gellish Database Table Definition

The document 'The Gellish Database Definition' defines the full set of columns in a Gellish database table as well as the standardised subsets that are defined for usage in particular kinds of applications.

Other documentation about Gellish

Other documentation about Gellish can be found on http://sourceforge.net/project/showfiles.php?group_id=28353.For example, the “Gellish Application Handbook” provides extensive guidance on how to express information or knowledge in the Gellish English language about physical objects, their design and operation, in other words on what to fill-in in a Gellish database when that language is applied. The 'Gellish English language extension manual' (also referred to as the ‘Guide on STEPlib’) desribes how proprietary extensions to the dictionary can be specified and how they can be proposed as additions to the official Gellish English dictionary.Furthermore, the website contains examples, such as the document 'Example of a Road in Gellish' and an accompanying Gellish database table as an Excel spreadsheet. This forms an illustrative example of the expression of knowledge about roads and an example of information about a particular road, both expressed in Gellish English with a translation to Gellish Dutch and vice versa.