Review: Basis, basic feasible Find an example of a 2-element set of formulas such that each element of is satisfiable but is not. (b) Show that {P, Q, (PQ)} is an unsatisfiable 3-element set, each of whose 2-element subsets is satisfiable. (c) For every n 3, find an example of an unsatisfiable n-elements set, each of whose (n 1)-element subsets is satisfiable. and dual solutions Let (P) be the following linear program. max 3 5 4 0 4 x s.t. 1 2 1 2 3 1 2 2 1 2 x = 21 16 x 0 (a) Write down the dual (D) of (P). (No justifications required.) (b) For each of the following sets of variable indices, follow these steps: Determine if it is a basis. Explain why. If it is not a basis, then stop here. Given that it is a basis, determine its corresponding basic solution. Is it feasible? Explain why. If it is not feasible, then stop here