brookeknowles / cs705_a2

University assignment on model checking and hardware verification

CS705_A2

This was an assignment I did for a university class on formal methods for safety critical software.

Q1: Model-checking LTL properties on concurrent processes.

Part-A

Model Petersons mutual exclusion algorithm in Promela.

Part-B

Represent the following properties in LTL and verify them against at least 2 processes from above.

• Property-1 (Safety property): Multiple processes cannot enter the ciritical section together.
• Property-2 (Liveness property): If a process is waiting, eventually it will enter the critical section.
• Property-3 (Liveness property): Any process not in the critical section will eventually enter the critical section.

Q2: Using SMT solvers for hardware verification.

Majority voter is a protocol used in fault tolerant systems. Consider 3-processors A, B, and C, carrying out the same computation simultaneously. Any of these processors might suffer from transient faults during processing. In the majority voter protocol, an output Y is set depending upon the majority result produced from the processors. The truth table below describes the majority voter protocol:

A	B	C	Y
0	0	0	0
0	0	1	0
0	1	0	0
0	1	1	1
1	0	0	0
1	0	1	1
1	1	0	1
1	1	1	1

The boolean equation: Y = (¬A /\ B /\ C) \/ (A /\ ¬B /\ C) \/ (A /\ B /\ ¬C) \/ (A /\ B /\ C) gives the functional description of the truth-table above.

A hardware engineer states that he/she will implement the above circuit using the equation below:

Y' = (A /\ B) \/ (B /\ C) \/ (A /\ C)

Prove using the SMT solver that Equations (1) and (2) are equivalent. If they are not, show why not?