An expert system is an interactive program which attempts to answer a set of questions.
It is deliberately meant to be used in a "conversational" manner - a natural language interface.
No input is meant to depend upon extensive knowledge of the technicalities of the program. It is not a database as such, but allows many people use the knowledge of an expert.
This knowledge is updated regularly as the expert learns more, but only bacause the technology allows this. Size and location are two points which need to be evaluated before and expert system is installed.
An operating system is a program that provides an interface between the software and the hardware. It is not necessary to know about the operating system to use the computer, but sometimes it is... The operating system also provides a number of services which are available to programs to use.
A number of prominent operating systems:
Applications software is complete. It cannot be altered by the end user. This menas than the user does not program the machine, but only uses it.
Typical Applications software types include Word Processors, Data Bases, Spread Sheets, while "unusual" applications include Desktop Publishing, CAD/CAM/CAE/CASE/CAI, Expert Systems, and Communications packages.
Types of software, and the tasks it is used for:
|Text (eg. letters/memos/novels)||Word Processing|
|Mathematical (eg. Accounting)||Spread Sheets|
|Information (eg. LISTS)||Data Bases|
A DBMS is a set of programs which create, manipulate, manage, protect and provide acces to the database. Note that data is a set of facts, which are unorganised and meaningless. Information is the same set of data, organised and made meaningful.
Protection to the data is achieved from illegal use by passwords and/or PIN numbers, and from the operator screwing up by various verification procedures and read only records.
A DBMS helps the user do complicated processing. It can remove the need for a specialist programmer.
There are four different styles of database: list, heirarchical, network, and relational. They are listed in increasing orders of complexity.
In summary, a database saves
PURPOSE: display name, age and sex for all persons over 21 years of age.
IN QL: LOCATE PERSON WHEN AGE GE 21. LIST NAME, AGE, SEX. EXHAUST LIST.
This example eliminates maths, with GE standing for "greater than or equal to", or >=. The one below uses maths, but has a much more English way of thinking:
PURPOSE: display inventory for all items which none of which are on hand and orders
IN QL: LIST INVENTORY DESCRIPTION WITH NUMBER = "0" AND ORDER DATE BEFORE 10/10.