 In the figure, our two events e and f are pictured as rectangles (to distinguish these from the circled worlds of a Kripke model). The formula appearing inside an event’s rectangle is what is announced when the event occurs. So event e represents the announcement of p, and event f represents the announcement of \(\top\). The event that actually occurs, called the “point”, is indicated using a double rectangle; in this case, the point is e. The only event that a considers possible is e because the only a-arrow leaving e loops right back to e. But all of the agents in our agent set \(\sA\) other than a mistakenly consider the alternative event f as the only possibility: all non–a-arrows leaving e point to f. Furthermore, from the perspective of event f, it is common knowledge that event f (and its announcement of \(\top\)) is the only event that occurs: every agent has exactly one arrow leaving f and this arrow loops right back to f. Accordingly, the structure pictured above describes the following action: p is to be announced, agent a is to know this, and all other agents are to mistakenly believe it is common knowledge that \(\top\) is announced. Structures like those pictured in Figure 3 are called action models. 