Large-scale complex systems have been traditionally characterized by a large number of variables, nonlinearities and uncertainties. Their decomposition into smaller, more manageable subsystems, possibly organized in a hierarchical form, has been associated with intense and time-critical information exchange and with the need for efficient decentralization and co-ordination mechanisms.

The last decade of the past century and the beginning of the 21st century have revealed new characteristic features of industrial and non-industrial large-scale complex systems. In particular the issue of system complexity has become transparent. Moreover, the enterprise of the present time are to operate in a highly networked environment and there is an ever more increased concern for integration of various technologies and for economic, environmental and social aspects. Consequently the design of control and decision support systems must take into account more aspects and needs additional skills and tools. At the same time, the recent advances in computer and communication technologies can provide effective tools and adequate technical infrastructures to support the design and implementation of control and decision support systems for the large-scale complex system applications of the present time.

The main event of this TC are symposia entitled "Large Scale Systems: Theory and Applications" (abbreviated as LSS). The inaugural edition has held in Udine, Italy in 1976. Since then, at a three-year succession, the Symposium took place in Toulouse, France (1980), Warsaw, Poland (1983), Zurich, Switzerland (1986), Berlin, GDR (1989), Beijing, China (1992), London, UK (1995), Partas, Greece (1998), Bucharest, Romania (2001), Osaka, Japan (2004) , Gdansk, Poland (2007), Lille, France (2010) and Shanghai, China (2013). This year it is happening in Dublin from August 12-14, 2025.

It can be appreciated now that several subfields that are traditional for LSS events remain of increasing interest to the scientific community, such as decentralized and hierarchical control, model reduction, optimization and complex system analysis. Traditional applications of LSS methods, such as power, gas, transportation, manufacturing, water systems agriculture, process industry, robotics and communication networks are still of interest. However, these application systems have been continuously developing and new challenges have emerged. In particular, the study of large-scale complex networks has become an active area of scientific research inspired largely by the empirical study of real-world networks.

We are pleased to invite you to the 17th IFAC Symposium on Large Scale Complex Systems: Theory and Applications, scheduled for August 12–14, 2025, at University College Dublin, Ireland.