Pursuing Stacks

Abstract

Pursuing Stacks (\`A la poursuite des Champs) First episode: The modelizing story (histoire de mod\`eles) by Alexander Grothendieck. Grothendieck began writing Pursuing stacks under the influence of some letters of the beginning of 1983 that motivates him to write to Daniel Quillen as a Take-off, adding some letters to Lawrence Breen as an appendix and outline of the program, of a systematic reflection on the foundations of non-commutative (co)homological algebra and its coefficients, and of homotopical algebra. The text is written in English as it grew out of the correspondence with R Brown and D Quillen. The title is based on the intuition that stacks are the unifying concept for a synthesis of homotopical algebra and non-commutative cohomological algebra. The first episode called "The modelizing story" is a comprehensive reflection about foundational matters in homotopy theory, and just after the beginning, the reflection diverged from stacks and rather centers itself around understanding the manifold ways of modeling homotopy categories. Grothendieck continued the reflection until November of the same year. In June he writes the first words of the introduction and retakes it in February of 1984 when the reflection has ended months ago (meanwhile he reflects on pseudo-lines and writes "L'Esquisse d'un Programme"). This introduction begins to take a more personal air and then he moves to French. The months that follow see the beginning of "R\'ecoltes et Semailles". The whole project would be included in a volume of the "R\'eflexions math\'ematiques", but the whole series never saw the light. The 2015 edition by "thescrivener" is in the public domain. This edition is an extended and revised version by Mateo Carmona with the collaboration of Ulrik Buchholtz.