1. Cournot model is a special form of Nash equilibrium. It is somewhat similar to the relationship with Chinese cuisine and Sichuan cuisine. Nash equilibrium is the equilibrium of oligopoly market. Cournot model is a duopoly market. Cournot is for the convenience of analyzing problems. Assuming that there are only two manufacturers in the market, we can calculate their respective reaction curves.

Cournot model is also called Cournot duopoly model or duopoly model. Cournot model is an early oligopoly model. It was put forward by French economist Cournot in 1838, which is the earliest version of Nash equilibrium application. Cournot model is usually used as the starting point of theoretical analysis of oligopoly. Cournot model is a simple model with only two oligarchs, also known as "double-headed model". The conclusion of Cournot model can be easily extended to the case of three or more oligarchs.

3. Nash equilibrium can be understood like this. If other participants don't change their strategies, then no one can gain greater utility or benefit by changing their strategies. Nash further proved that there is at least one such equilibrium in the game of finite behavior. Nash equilibrium is the most important and generalized equilibrium concept in game theory. It refers to a strategy combination of all participants: in this combination, given the strategies of other participants, no one actively changes their own strategies. In other words, the strategy that constitutes Nash equilibrium is optimal for everyone.

Nash equilibrium has a very important feature, which is the consistency of belief and choice. In other words, the choice based on faith is reasonable, and the beliefs that support this choice are also correct. So Nash equilibrium has the characteristics of predictive self-execution: if everyone thinks that this result will appear, then this result will really appear. Of all the combinations of the game, only Nash equilibrium can satisfy the condition of self-realization.

We can understand Nash equilibrium from another angle: if all participants reach an agreement before the game. Our question is: Do you consciously abide by this agreement without external enforcement? If everyone actively abides by the agreement, the agreement constitutes a Nash equilibrium. In other words, with this agreement, when others abide by it, no one will take the initiative to choose an action different from this agreement. The protocol is a Nash equilibrium. On the contrary, if someone deviates from the agreement unilaterally, the agreement is not Nash equilibrium.