KKM theory and some applications in nonlinear analysis

Contemporary mathematical analysis studies in the last decades increasingly take place in the field of non-linear functional analysis. It has been shown to be significant studies of non-linear models that appear in various problems that have applications in practical problems, for example in physics, engineering, economics, operational research, and so on. Within the framework of non-linear functional analysis, KKM theory is rapidly developing over the last three decades and has a very important place. Here we give some aspects of the application of KKM theory.