1. FORMAL METHOD

2. Formal Method Formal methods are system design techniques that use rigorously specified mathematical models to build software and hardware systems. In contrast to other design systems, formal methods use mathematical proof as a complement to system testing in order to ensure correct behavior. Formal methods refers to a variety of mathematical modeling techniques that are applicable to computer system design. “ Formal methods are mathematical approaches to software and system development which support the rigorous specification, design and verification of computer systems.”

3. Advantage of formal method Formal Method forces the System Analyst and Designer to think carefully about the specification as it enforce proper engineering approach using discrete mathematics. Formal Method forces the System Analyst and Designer to see all the different possible states for any given variables and functions thus will avoid many faults and therefore reduces the bugs and errors from the design stage onward.

4. Disadvantage of formal method Formal Method requires the person to know how to apply discrete mathematics. It will obviously slow down the analysis and design stage resources and time therefore also the cost of the project. There are too many different formal methods and most of them are not compatible with each other. Formal methods do not guarantee that a specification is complete. For each variable and function, it just forces the System Analyst and Designer to view the specification from a different perspectives but it does not guarantee that variable and functions will not be left out.