Three adults and three children are on the left side of the river. Each adult weighs 150 pounds. Each child has half the weight of an adult, so each child weighs 75 pounds. They all want to cross to the right side of the river. However, the only means of transportation they can use is a boat, and the boat can carry a maximum of 225 pounds. Thus, the boat can carry one adult, one adult and one child, one child or two children. Any adult or child can operate the boat, but the boat cannot be operated without having at least one person on the boat. The goal is to come up with a plan for moving everyone from the left side to the right side using multiple boat trips.

a. Describe the initial state and the goal, using PDDL.
b. Define appropriate actions for this planning problem, in the PDDL language.
c. For each action, provide a name, arguments, preconditions, and effects. Also, give a complete plan (using the actions described) for getting from the start to the goal state.