Model-based specification is an approach to formal specification

Formal specification

In computer science, a formal specification is a mathematical description of software or hardware that may be used to develop an implementation. It describes what the system should do, not how the system should do it...

 where the system specification

Requirements specification

Requirements specification in systems engineering and software engineering is the direct result of a requirement analysis and can refer to*Software Requirements Specification*Hardware Requirements Specificationor both.-See also:*Design specification...

 is expressed as a system state model

System model

A system model is the conceptual model that describes and represents a system. A system comprises multiple views such as planning, requirement , design, implementation, deployment, structure, behavior, input data, and output data views...

. This state model is constructed using well-understood mathematical entities such as sets and functions

Function (mathematics)

In mathematics, a function associates one quantity, the argument of the function, also known as the input, with another quantity, the value of the function, also known as the output. A function assigns exactly one output to each input. The argument and the value may be real numbers, but they can...

. System operations are specified by defining how they affect the state of the system model.

The most widely used notations for developing model-based specifications are VDM and Z

Z notation

The Z notation , named after Zermelo–Fraenkel set theory, is a formal specification language used for describing and modelling computing systems. It is targeted at the clear specification of computer programs and computer-based systems in general.-History:...

 . These notations are based on typed set theory

Set theory

Set theory is the branch of mathematics that studies sets, which are collections of objects. Although any type of object can be collected into a set, set theory is applied most often to objects that are relevant to mathematics...

. Systems are therefore modelled using sets and relations between sets.

Another well-known approach to formal specification is algebraic specification

Algebraic specification

Algebraic specification, is a software engineering technique for formally specifying system behavior. Algebraic specification seeks to systematically develop more efficient programs by:...

.