To show that a compound proposition is satisfiable, we need to find a particular assignment of truth values to its variables that makes it true. However, to show that a compound proposition is unsatisfiable, we need to show that every assignment of truth values to its variables makes it false. Determine (without using a truth table) whether each of the following compound propositions is satisfiable. Justify your answer. a. (p q) Lambda (p q) Lambda (p q) b. (p q) Lambda (p q) Lambda (q r) Lambda (q r) Lambda (q r) c. (p doubleheadarrow q) Lambda (q doubleheadarrow q) A truth table can be used to determine whether a compound proposition is satisfiable. However, as the number of variables in a compound proposition grows, using a truth table to determine whether it is satisfiable becomes impractical. No algorithm is known to determine in a reasonable amount of time whether an arbitrary compound proposition with a large number of variables (i.e., thousands, millions) is satisfiable. This is an important unsolved problem in Computer Science