Kleene stars of the plane, polylogarithms and symmetries. - Vincel Hoang Ngoc Minh; Quoc Hoan Ngô; Gérard Henry Edmond Duchamp; V. Hoang; Ngoc Minh; Ngo Quoc; Phan Dang Luu; Kien An; Hai Phong; Viet Nam (CoRR, 2018)