Hello!

Other advanced textbooks, like Mas-Colell' and Varian's, give at least two definitions of pareto efficient allocations: the "weak one" and the "strong one". The differences between them are useful for the proofs of the first and second welfare theorems. I can't find in chapter 5 something related to this differences. Why do Jehle and Reny's proofs does not need them? (By the way, I do prefer this proofs and this exposition than the ones from Varian and Mas-Colell).