“…This is not surprising because, in terms of mathematics, the theory involves a variety of fields: probabilistic analysis, calculus of variations, the analysis of partial differential equations, and so on. Especially, the linear quadratic (LQ) MFG theory has been treated by many researchers with fruitful results; Huang et al [
1] developed a state aggregation technique to obtain decentralized control laws for a large but finite population with the infinite horizon discounted costs; Bardi [
23] provided a quadratic Gaussian solution to a system of HJB and FPK equations in the case of one‐dimensional state space; Moon and Başar [
24] investigated the LQ risk‐sensitive MFG and obtained
‐Nash equilibria; Huang and Zhou [
25] analyzed the connection and difference of the direct approach and the fixed point approach; Huang and Yang [
26] studied an asymptotic solvability problem for LQ‐MFGs and established a decentralized
‐Nash strategy.…”