Question

You have decided to design a system to help investors determine when to buy and sellinput before buying or selling. The first expert is Pain Webster – a famous stock broker.The secondexport is Meg A Cash, a self-made billionaire in the stock market. The third expert is Madame Trelawney, world famous psychic. The fourth expert is ProfessorLockhart. Before you recommend a decision (on buying a certain stock) you get input from all the experts. After receiving advice/input from all experts, and analyzing outcomes over several cases, you have come to the following conditions to implement your “expert system” to help investors buy stock.

a.

Buy if Pain and Meg both say “yes” and the psychic says “no”

b.

Buy if psychic says “yes” and professor says “no”

c.

Buy if the psychic and the professor both say “no”

d.

Don’t buy in all other cases.

Construct the truth table for the above expert system, find the Boolean function to implement the system and implement the circuit (using basic combinational logic gates).

Answer 1

Lets suppose inputs A -> Pain, B -> Meg, C -> Psychic and D -> Professor.

Function is sum of all expressions where output is true :

A'B'C'D' + A'B'CD' + A'BC'D' + A'BCD' + AB'C'D' + AB'CD' + ABC'D' + ABC'D + ABCD'

Plotting K-Map for simplification:

We get 1 octet D'(as D' is unique in all the expressions of the octet) and 1 pair ABC' (as ABC' is common in both the expressions of the pair). So the simplified expression is ABC' + D'.

Circuit: