The notion of complexity is an important contribution of logic to theoretical computer science and mathematics. This volume attempts to approach complexity in a holistic way, investigating mathematical properties of complexity hierarchies at the same time as discussing algorithms and computational properties. A main focus of the volume is on some of the new paradigms of computation, among them Quantum Computing and Infinitary Computation. The papers in the volume are tied together by an introductory article describing abstract properties of complexity hierarchies.

This volume will be of great interest to both mathematical logicians and theoretical computer scientists, providing them with new insights into the various views of complexity and thus shedding new light on their own research.

"Foundations of the Formal Sciences" (FotFS) is a series of interdisciplinary conferences in mathematics, philosophy, computer science and linguistics. The main goal is to reestablish the traditionally strong links between these areas of research that have been lost in the past decades.

The second conference in the series had the subtitle "Applications of Mathematical Logic in Philosophy and Linguistics" and brought speakers from all parts of the Formal Sciences together to give a holistic view of how mathematical methods can improve our philosophical and technical understanding of language and scientific discourse, ranging from the theoretical level up to applications in language recognition software.

Audience: This volume is of interest to all formal philosophers and theoretical linguists. In addition to that, logicians interested in the applications of their field and logic students in mathematics, computer science, philosophy and linguistics can use the volume to broaden their knowledge of applications of logic.

The notion of complexity is an important contribution of logic to theoretical computer science and mathematics. This volume attempts to approach complexity in a holistic way, investigating mathematical properties of complexity hierarchies at the same time as discussing algorithms and computational properties. A main focus of the volume is on some of the new paradigms of computation, among them Quantum Computing and Infinitary Computation. The papers in the volume are tied together by an introductory article describing abstract properties of complexity hierarchies.

This volume will be of great interest to both mathematical logicians and theoretical computer scientists, providing them with new insights into the various views of complexity and thus shedding new light on their own research.

Infinity can feature in games in various forms: we can play games of infinite length, with infinitely many players, or allow for infinitely many moves or strategies. Games of infinite length have been thoroughly investigated by mathematicians ard have played a central role in mathematical logic. However, their applications go far beyond mathematics: they feature prominently in theoretical computer science, philosophical "Gedankenxperiments," as limit cases in economical applications, and in many other applications. The conference "Foundations of the Formal Sciences V" focused on games of infinite length, but was very open to include other notions of infinity in games as well. It brought together researchers from the various areas that employ infinitary game techniques to talk about similarities and dissimilarities of the different approaches and develop cross-cultural bridges. This volume contains the fully refereed proceedings of the conference and provides a healthy and interesting mixture of research papers and surveys for a broad audience.

This volume takes a reflective position with respect to the conference series "Foundations of the Formal Sciences" (FotFS) and asks: * What are the Formal Sciences? * Can we develop a theoretical classification of the sciences that juxtaposes the formal sciences to the natural sciences, social sciences, and humanities? Can we do this solely by identifying common methodological features? * Can we identify changes of the notion of formal sciences over time? How were the areas that we now conceived as the "Foundations of the Formal Sciences" classified throughout history? Investigating the "History of the Concept of the Formal Sciences" to find answers to an array of questions with this wide scope, you need an enthusiastic group of researchers interested in going beyond the traditional boundaries of their subjects covering at once the philosophical, historical and logical issues at hand, like the authors of this volume. The papers in this volume stand witness to our success in touching the mentioned questions. It will be of interest to philosophers, sociologists, historians, and logicians, and covers many aspects of the history of the formal sciences from the Bronze Age to the early XXIst century.