Formal Methods Concepts and Machines Assignment

LO1 Describe and evaluate fundamental formal methods concepts

LO2 Analyse and critically review the role of formal methods in the software life cycle

LO3 Critically evaluate the role of tools and methods supporting formal software development

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The finite state machines produced The construction of combined machines Describe the meaning of a finite state machine

LO2 The simulation and test cases The definition of equivalence Transformation of one formal description to another one

LO3 Critical evaluation of formal methods and tools Use of Statecharts to formalise a real world example

a) Produce a model of each of the following machines together with an appropriate set of documentations which includes: the specification of the models, the models themselves, design decisions and their simulation and test cases (using JFLAP):

i) Machine N for dispensing a number of snacks.

ii) Machine M for dispensing a number of snacks.

iii) Machine P for dispensing a drink.

iv) A combined P-N machine in which a number of snacks are dispensed after the drink. Note: payment for machine P is separate from machine N.

v) A combined P-M machine in which a number of snacks are dispensed after the drink. Note: payment for machine P is separate from machine M.

vi) A combined M-P machine in which a drink is dispensed after a number of snacks. Note: payment for machine M is separate from machine P.

b) Explore the notion of equivalence between FSMs in general.

Critical evaluation of formal methods and tools Use of Statecharts to formalise a real world example

a) Critically analyse the limitations of finite state machines (FSM) in modelling reactive systems and discuss how these limitations are overcome in Statecharts.

The procedure for exiting the red room and entering the green room is as follows:

• Enter the right orange corridor via door D2.

• If infrared sensor IR1 detects somebody then door D2 will close.

• If D2 is closed then the right corridor is decontaminated. This procedure takes 1 minute.

• If the decontamination procedure has completed then the door D3 will open.

• If infrared sensor IR1 does not detect somebody then door D3 will close.

• If door D3 is closed then door D2 will open.

• The two decontamination procedures are different in that the left one is lethal to humans. The right one is human friendly.

• As experiments in the red room are potential dangerous doors D2 and D3 should not be open at the same time. Similarly doors D0 and D1. Specify the above AREA-42 system using Statecharts.

Check your answer by simulating that a staff member first enters the left orange corridor and then enters the red room. After a while the staff members returns to the green room via the right orange corridor.