Dacorogna, BGangbo, WKneuss, O2018-11-082018-11-082018-11-08201810.1016/j.anihpc.2017.04.005https://infoscience.epfl.ch/handle/20.500.14299/151034WOS:000427331800002Symplectic factorization, Darboux theorem and ellipticitytext::journal::journal article::research article