## Has unconditional convergence ever been proved other than by deducing it from absolute convergence?

Nobody’s answering this question so I’ll try it here. This is really a reference request: Has a certain kind of proof ever been used? A series ∑nan converges absolutely if ∑n|an|<∞. It converges unconditionally if it converges to a finite number and all of its rearrangements converge to that same number. For series of real … Read more