1, the problem of p versus NP is the most difficult arithmetic problem in the world.

The typical problem of NP problem is Hamilton path problem: given n cities to visit, how can we do this without visiting cities? If you can give a solution, you can easily check whether it is correct. Then you will get a bonus of 6.5438 million US dollars (about 6.6 million yuan).

The essence of P and NP problems is whether the reverse is correct: if I have an effective way to check the solutions of a problem, is there an effective way to find these solutions?

Most mathematicians and computer scientists think that the answer is no, but for ordinary people, understanding this problem is a matter of feeling.

2. Naville-Stokes equation

Just as Newton's second law describes that the speed of an object will change under the action of external forces, Naville-Stokes equation describes how the speed of fluid flow changes under the action of external forces such as pressure, viscosity and gravity.

Naville-Stokes equation is a set of differential equations, which describes how a specific quantity changes with time after some initial initial conditions are given.

In the case of equations, we start with some initial fluid flows, and differential equations describe the evolution process of fluids. For a simple example, mixing cream in coffee in the morning and explaining what happened mathematically can win $6.5438+0 million (about 6.6 million RMB).