Logic Design Puzzle/Interview Question challenge

Consider the Boolean function F = (x1 + x3 + x4)(x2 + x3 + x4)(x1 +x2 +x4)(x1 +x3 +x4)(x1 +x2 + x3).
Find an assignment of x1; x2; x3 and x4 that will make F=1.
You are not allowed to transform the expression into any other form including SOP, K-Map etc.
(a) Explain the strategy that you used clearly.
(b) Write down the assignment to X.

Write function F in Problem above in sum-of-products form. Find an assign-ment of x1; x2; x3 and x4 that will make F=1. As before, no transformations are allowed.
(a) Explain the strategy that you used clearly.
(b) Write down the assignment to X.

Use the sum-of-products form of F that you found in Problem 2. Find an assignment of x1; x2; x3 and x4 that will make F=0.

Answer the following questions:
(a) Which assignment to F was easier, assignment done on the SOP or the POS form? Why?
(b) Which assignment to F was harder, assigning 1 to F in problem 2 or assigning 0 to F in problem 3? Why?
(c) Compare the di difficulty of Problem 1 and Problem 3.
(d) Are your solution strategies general enough for any F given to you?