Matematikkens fundament

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He [Kronecker] was, in fact, attempting to describe and to initiate a new branch of mathematics, which would contain both number theory and alge- braic geometry as special cases.-Andre Weil [62] This book is about mathematics, not the history or philosophy of mathemat- ics. Still, history and philosophy were prominent among my motives for writing it, and historical and philosophical issues will be major factors in determining whether it wins acceptance. Most mathematicians prefer constructive methods. Given two proofs of the same statement, one constructive and the other not, most will prefer the constructive proof. The real philosophical disagreement over the role of con- structions in mathematics is between those-the majority-who believe that to exclude from mathematics all statements that cannot be proved construc- tively would omit far too much, and those of us who believe, on the contrary, that the most interesting parts of mathematics can be dealt with construc- tively, and that the greater rigor and precision of mathematics done in that way adds immensely to its value.

This primer on mathematics formalisation provides a rapid, hands-on introduction to proof verification in Lean.After a quick introduction to Lean, the basic techniques of human-readable formalisation are introduced, illustrated by simple examples on maps, induction and real numbers. Subsequently, typical design options are discussed and brought to life through worked examples in the setting of simplicial complexes (a higher-dimensional generalisation of graph theory). Finally, the book demonstrates how current research in algebraic and geometric topology can be formalised by means of suitable abstraction layers.Informed by the author's recent teaching and research experience, this book allows students and researchers to quickly get started with formalising and checking their proofs. The core material of the book is accessible to mathematics students with basic programming skills. For the final chapter, familiarity with elementary category theory and algebraic topology is recommended.

Die Schulmathematik vermittelt meist nur einen sehr eingeschränkten Einblick in die beweisorientierte und axiomatisch aufgebaute moderne Mathematik ¿ Studienanfänger werden daher oft unvorbereitet von der Hochschulmathematik getroffen.Dieses Lehrbuch erleichtert den nötigen Übergang zum selbstständigen Erarbeiten und Lernen mathematischer Beweise und Inhalte: Es motiviert die Lesenden, selbst aktiv zu werden und sich alleine an den gegebenen Problemstellungen zu versuchen. Dabei wird viel Wert auf leichte Sprache, ausführliche Erklärungen und detaillierte Beispiele gelegt. Somit ist das Buch optimal zum Selbststudium, als Material für Online-Lehrveranstaltungen oder als Ergänzung zu klassischen Mathematik-Vorkursen geeignet.Die einzelnen Kapitel können weitgehend eigenständig und selektiv gelesen bzw. bearbeitet werden, sind aber einheitlich aufgebaut: Jedes Kapitel orientiert sich inhaltlich an einer zu Beginn dargestellten Leitfrage. Auf dem Weg zur Antwort werden die Lesenden von ausführlichen Erläuterungen, Schnellaufgaben, klassischen Übungsaufgaben und Wiederholungsaufgaben begleitet. Die Relevanz der Ergebnisse wird abschließend erläutert; an einigen Stellen gehen die Autoren sogar auf aktuelle Forschung ein oder geben Ausblicke auf tiefere mathematische Erkenntnisse.Die mathematische Basis dieses Buchs ist die zweisemestrige Vorlesung zur Elementarmathematik für das Haupt- und Realschul-Lehramt an der Goethe Universität Frankfurt. Daher eignet sich das Buch besonders gut für Lehramtsstudierende (auch für das gymnasiale Lehramt), als Anregung für Lehrkräfte oder als Ausblick für motivierte Schüler sowie als Brückenkursmaterial.

Starting with the historical evolution of computer and communications networks and their security, the book then arrives at the main definitions of cryptography and network security. Next, the basics of information theory, how to measure information, the information associated with a certain source are also discussed. Source codes are presented, along with the concepts of information transmission, joint information, conditional entropy, mutual information and channel capacity. Computer networks are discussed, including the main protocols and network architectures, and the important TCP/IP protocol. Network security, a topic intrinsically connected to computer networks and the Internet, is presented, along with information about basic hacker attacks, alternatives to prevent attacks, data protection and secure protocols. The information theoretical aspects of cryptography are described including the hash function. An appendix includes a review of probability theory. Illustrations and graphics will help the reader understand the theory.