On "requirements":
Bech (Extreme Programming):
Requirements gathering is in a phase that produces a static document, but an activity producing detail, just before it is needed, throughout development
Cohn (Scrum):
Scrum projects do not have an upfront analysis or design phase; all work occurs within the repeated cycle of sprints
Poppendieck (Lean):
And those things called requirements? They are really candidate solutions; separating requirements from implementation is just another form of handover
[source: edx course on Agile Software Development]
