Cohomology

In January 1984, Alexander Grothendieck submitted to the French National Centre for Scientific Research his proposal “Esquisse d’un Programme.” Soon copies of this text started circulating among mathematicians. A few months later, as a first-year...

Freedom is a powerful incentive to do the best we can. As I can attest from examples in my own work, it sometimes leads to dead ends, but that is a small price to pay.

From the data, you have this remnant of a real object that you want to resurrect. Before you can start to do that, the first thing you need to know is, is it really coming from such and such an object? Are there some good tests or signatures for that?