**3. Memetic Strategies**

If the particle swarm is regarded as a social population, the three parts of the particle update speed reflect the balance of the population with respect to the global optimum and the local optimum. The particle update speed can be regarded as the cognition of the social population in the evolutionary direction. The evolutionary update speed at the current moment *t* can provide a reference basis for the evolutionary update speed at the next moment *t* + 1. During evolution, the evolution of a single particle needs to refer to its own previous evolutionary state and the evolutionary state of the population. The main advantage of the PSO algorithm is that it is simple, effective and easy to implement. However, the PSO algorithm faces premature convergence and easily falls into a local optimal solution [34].

Compared with other group-based methods, the ability of PSO to micromediate and avoid local optima is weaker, which is mainly due to the lack of diversity in the search process [35]. Therefore, we improve the evolutionary diversity of the population in the search process; the basic flow of the cultural strategy is shown in Figure 2.

**Figure 2.** Flow chart of memetic strategy for MT inversions.
