Cet ouvrage presente les bases de la theorie de la complexite des algorithmes et en derive les theoremes fondamentaux de decidabilite et d'indecidabilite pour la logique et l'arithmetique, dont le premier theoreme d'incompletude de Godel. En faisant reposer toutes les preuves sur le codage de l'arret d'une machine de Turing, on a souligne l'homogeneite et l'unite profonde des resultats presentes. L'approche par les machines de Turing est tres accessible grace a la familiarite donnee aujourd'hui par l'informatique. Le livre n'est pas une encyclopedie exhaustive, mais parvient de facon rapide a...

The aim of this book is to present recently discovered connections between Artin's braid groups En and left self-distributive systems (also called LD systems), which are sets equipped with a binary operation satisfying the left self-distributivity identity x(yz) = (xy)(xz). (LD) Such connections appeared in set theory in the 1980s and led to the discovery in 1991 of a left invariant linear order on the braid groups. Braids and self-distributivity have been studied for a long time. Braid groups were introduced in the 1930s by E. Artin, and they have played an increas ing role in mathematics in...