The economic world today faces a multitude of challenges due to several factors, such as new finance. These factors affect the progress of the economy and give rise to new complicated situations that require new answers. Quantitative approaches offer an excellent source of tools to be adopted and applied to economic models, finance, and other social problems, offering new solutions. The new situations arising in these areas in recent years require the development of new models and new techniques in the field of applied mathematics.

Complexity, appearing in models reporting important advances in the scientific study of complex systems, is characterised by interactions between components that produce new information about the future evolution of such systems. Study of the complex characteristics of such systems is a rapidly growing field, and there is an increasingly urgent need to explore and bring together theoretical, practical, and state-of-the-art applications in modern economic models, finance, and other social problems.

The aim of this Special Issue is to gather a collection of articles reflecting the latest developments in different fields of economic modelling, finance, and social problems. As there are many new models being proposed for these areas in very different fields, we invite researchers who are working on these issues to submit their work to our Special Issue. Authors are invited to submit high-quality papers describing original, unpublished research in related scientific areas, and all contributions should bridge the gap between theory and practice in such problems and will be of interest to both researchers and practitioners.

Potential topics include but are not limited to the following:

• Development and modification of financial modelling
• Analysis of bifurcation and complexity of financial models
• Multi-stability and synchronisation of financial and biological models
• The influence of memory in financial and biological models
• Applications of discrete dynamical systems in cryptography
• Applications of mathematical analysis to financial economics and biological sciences