@Misc{ GigRig17, author = { Gigli, Nicola and Rigoni, Chiara }, title = { Recognizing the flat torus among $RCD^*(0,N)$ spaces via the study of the first cohomology group }, journal = { }, year = { 2017 }, pages = { }, URL = { http://cvgmt.sns.it/paper/3424/ }, note = { cvgmt preprint} }