This book provides a basic introduction to reduced basis (RB) methods for problems involving the repeated solution of partial differential equations (PDEs) arising from engineering and applied sciences, such as PDEs depending on several parameters and PDE-constrained optimization.

The book presents a general mathematical formulation of RB methods, analyzes their fundamental theoretical properties, discusses the related algorithmic and implementation aspects, and highlights their built-in algebraic and geometric structures.

More specifically, the authors discuss alternative strategies for constructing accurate RB spaces using greedy algorithms and proper orthogonal decomposition techniques, investigate their approximation properties and analyze offline-online decomposition strategies aimed at the reduction of computational complexity. Furthermore, they carry out both a priori and a posteriori error analysis.

The whole mathematical presentation is made more stimulating by the use of representative examples of applicative interest in the context of both linear and nonlinear PDEs. Moreover, the inclusion of many pseudocodes allows the reader to easily implement the algorithms illustrated throughout the text. The book will be ideal for upper undergraduate students and, more generally, people interested in scientific computing.

All these pseudocodes are in fact implemented in a MATLAB package that is freely available at https://github.com/redbkit

The first textbook on reduced basis methods, an approximation technique that has become very popular and successful in engineering and applied sciences Offers a balanced presentation of theoretical and computational aspects supported by a broad variety of relevant problems A first mathematically-driven foray into the field of reduced order modeling Includes supplementary material: sn.pub/extras

Autorentext
Paola Gervasio completed her PhD in Mathematics at the University of Milan (Italy) in 1995, and she has been an Associate Professor of Numerical Analysis at the University of Brescia (Italy) since 2005. She is the author of 4 books and of about 40 papers. Her research focuses on the approximation of partial differential equations by high-order methods and domain decomposition techniques, particularly in the context of multi-physics problems. Alfio Quarteroni is a Professor of Numerical Analysis at Politecnico of Milan and Professor Emeritus at EPFL of Lausanne. He is the author of 25 books and about 400 papers, and editor of 9 books. He is the recipient of two ERC Advanced Grants; the Galileian Chair from the Scuola Normale Superiore, Pisa; the Galileo international prize for Science; and an honorary doctorate in Naval Engineering from the University of Trieste. He is member of the Italian Academy of Science, the European Academy of Science, the Academia Europaea, and the Lisbon Academy of Science. His research interests include mathematical and numerical modeling for fluid mechanics, geophysics, medicine and the improvement of sports performance. His research group at EPFL carried out the mathematical simulation for the Alinghi sailing boat, which won the America's Cup in 2003 and 2007.

Inhalt
1 Introduction.- 2 Representative problems: analysis and (high-fidelity) approximation.- 3 Getting parameters into play.- 4 RB method: basic principle, basic properties.- 5 Construction of reduced basis spaces.- 6 Algebraic and geometrical structure.- 7 RB method in actions.- 8 Extension to nonaffine problems.- 9 Extension to nonlinear problems.- 10 Reduction and control: a natural interplay.- 11 Further extensions.- 12 Appendix A Elements of functional analysis.