Describe a practical situation that can be represented by a truth table of 4 variables. (or at least 3 for an extremetly good one).

- write down the truth table
- derive a reduced Boolean expression for the function representing the truth table, using K-map
-  verify your derivation using Boolean algebra
- investigate whether the SOP or the POS representation will be efficient
- draw a digital circuit to realize the practical situation
- convert your circuit to NAND-NAND or NOR-NOR type
- derive a set of functional test vectors to test this circuit

 Note: Your submission should be sufficiently different from any other submitted assignement. There will be a negative marking for all submission resembling each other, even by chance.