Why do we need formal specification? Discuss behavioral specification in detail.

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 We need formal specification because:-

-  Formal Specification involves investing more effort in the early phases of software development.
 - To explain why formal specification techniques help to discover problems in system requirements.
- To describe the use of:-
  ° algebraic technique(for interface specification) &
  °  model-based techniques( for behavioral specification)
- To introduced Abstract State Machine Model(ASMM)
- Formal Specification reduces requirements error as it forces a detailed analysis of the requirements.
 
Behavioral specification
- Behavioral specification describes constraints on the behavior of the implementation.
- Example:- functionality, safety, security, performances.
- Algebraic specification can cumbersome when the object operations are not independent of the object state.
- Model-based specification exposes the system state and defines the operations in terms of changes to that state.
- The Z notation is a mature technique for model-based specification. It combines formal and informal descriptions and uses graphical highlighting when presenting specifications.
       
Types of Behavioral Specification
 There are 4 types of behavioral specification, they are given below:-

a) Abstract Model Specification
- Defines operation in terms of a well-defined mathematical model.

b)Algebraic Specification
-Defines operations by a collection of equivalence relations.

c) State transition Specification
- Defines operation in terms of state and transitions.
 
d) Axiomatic Specification
-Defines operation by logical assertions

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