Db. Fairlie et Ja. Mulvey, INTEGRABLE GENERALIZATIONS OF THE 2-DIMENSIONAL BORN-INFELD EQUATION, Journal of physics. A, mathematical and general, 27(4), 1994, pp. 1317-1324
The Born-Infeld equation in two dimensions is generalized to higher di
mensions. Lorentz invariance is retained, and the resulting system is
completely integrable via linearization by Legendre transformation. Th
is generalization retains homogeneity in second derivatives of the fie
ld.