Five philosophers are sitting around a table, taking turns at thinking and eating. The atomic propositions are: ei: philosopher i is currently eating fi: philosopher i has just finished eating Write CTL formulas for the following statements. a. "Philosophers 1 and 4 will never eat at the same time." b. "Whenever philosopher 4 has finished eating, he cannot eat again until philosopher 3 has eaten." c. "Philosopher 2 will be the first to eat