We say a formula is in 3-CNF if it is the logical and of clauses, each of which is the logical or of exactly three distinct literals. Here is an example of a formula in 3-CNF, 1=(x2x3x4)(x1x2x4)(x1x3x4)(x2x3x4)(x1x2x3). We say that a formula is in 4 -CNF, if every clause has exactly four distinct literals. 1. When does the expression (x1x2d1)(d1x3x4) evaluate to true? 2. When does the expression (x1x2d1)(x1x2d1) evaluate to true? 3. When does (x1d1d2)(x1d1d2)(x1d1d2)(x1d1d2) evaluate to true? 4. Suppose we are given a formula in 4-CNF. Show that we can construct a formula in 3-CNF satisfying that (x)=(x) for all assignments x. 5. Conversely, suppose we are given a formula in 3-CNF. Show that we can construct a formula in 4-CNF satisfying that (x)=(x) for all assignments x. In the above, x1,x2,x3,x4,d1,d2 are variables. Note that a clause must contain distinct literals