Greetings, we have been looking at different ways that markets could be structured, and what those types of market structures would end up producing in terms of an output. As well as how much does a benevolent dictator appreciate that result versus how upset is a benevolent dictator with that particular outcome. And so, let's return to our little model we used to think this through, the number line measures the number of firms. And at this end, we have a situation when just one firm, and we call that situation monopoly. And at the other end, we have a situation with lots of firms, where we say N, and N is large. Okay, and this situation at this end of this of our number line, we called perfect competition. And in both cases, we figured out what the equilibrium was. In both cases, we figured out how we could model firm behavior. We understood that both of these parties, both the monopolist as well as the competitive industry, were full of firms who all had to live with the same hard rule of technology, the law of diminishing marginal product. So they all had U-shaped cost curves, and given those U-shaped cost curves and given the downward sloping nature of market demand, they ended up with an equilibrium result. Now we were able to figure out the equilibrium for competition and we were able to figure out the equilibrium for monopoly. But now we have to move into this middle zone, and this middle zone, basically where we have two firms up till some size, we called oligopoly. How many firms, how many firms does it take before an oligopoly looks just like it's maybe like a regular competitive market? Well, we're never really quite sure on that number. We know the idea is that if in fact an industry satisfied those four conditions we need for perfect competition, we as analysts, that's you too, you know how to show the equilibrium. You understand what the profits are. You understand what would happen if something comes along to tweak that equilibrium, my little bowl, cereal bowl with a ball bearing on the bottom. You got a nice, nice equilibrium, the ball bearing's resting kindly right at the bottom, and then suddenly some new regulation comes put in place. It kicks it around, it moves around for a while, and eventually comes to a new equilibrium. And you can do that, and you could do it over here too at monopoly. But now we're moving into an area where it's much harder to do that. And part of the reason that it's harder to do that is that the extremes points of that number line were what we call deterministic outcomes. I could see how firms are going to behave in competition. I can see how the firm is going to behave in monopoly. It's completely deterministic what their behavior is going to be, if you show me their cost curves and you show me the demand curves. The problem about this middle zone is there's something else going on. There's something else going on here, because you have to build equations, mathematics, graphs to help you explain how firms think about their rivals. The individual farmer, in the perfectly competitive case, the individual farmer, fix that problem. In the perfectly competitive case, the individual farmer doesn't care what his or her neighbor down the road does. If the neighbor down the road is planning 60% soybeans and 40% corn and this farmer decides to go 80% corn and 20% soybeans, they don't care what each other do, because they know that no matter what they do, they're too small to impact the market. The market price determined by the Board of Trade, by an external market. Each player knows that they're so small, it doesn't really matter. We don't have to worry about modeling behavior. Competition or monopoly, we don't either, because there is no competition. But when we get in this zone here, like I said before, but in an oligopoly, it's not just that if you think about the mid-size automobile market. Honda makes the Accord, Toyota makes the Camry, they're the very big players in the market. They don't just think about their cost curves and the demand curve out there. They have to think not only their cost curves and demand curves, but they have to think about their rival. So we're going to have to start rethinking what we're doing when we talk about this market structure. It's going to get harder to think through how oligopolies behave, thanks.