The rapid growth of fixed point theory and its applications over the past 80 years has led to a number of scholarly essays that examine its nature and its importance in nonlinear analysis, applied mathematical analysis, economics, game theory, and so forth. Many authors devoted their attention to investigate its generalizations in various different directions of the celebrated Banach contraction principle. For example, an interesting direction of research is the extension of the Banach contraction principle to multivalued maps, known as Nadler’s fixed point theorem, Mizoguchi-Takahashi’s fixed point theorem, and Berinde-Berinde’s fixed point theorem. Very recently, several new iterative methods for fixed points and equilibrium problems have been investigated. In the past decades, applications of the equilibrium problem have been extensively studied in different areas of science and generalized to the vectorial equilibrium problems for single-valued or multivalued maps and applied to solve optimization problems, variational inequality problems, saddle point problems, complementary problems, bilevel problems, and semi-infinite problems. Recent investigations and developments in fixed point theory as well as optimization theory have been applied to put fundamental sciences into the real world.

We cordially and earnestly invite researchers to contribute their original and high quality research papers which will inspire the advance in fixed point theory, equilibrium problems, and optimization problems.

Potential topics include, but are not limited to:

• Fixed point theory: existence, algorithms, and applications
• Geometric theory of Banach spaces: existence, inequalities, and applications
• Various abstract spaces and related nonlinear results
• Ulam-Hyers stability problems via fixed point theory
• Generalized Ekeland's variational principle and applications
• Generalizations of KKM theory and applications
• Variational inequality problems, equilibrium problems, complementarity problems, and their applications
• Optimization: theory, algorithms, and real world applications
• Split feasibility problems and applications
• Nonlinear differential equations and matrix equations