Opérateurs hyperboliques à caractéristiques de multiplicité constante

Cauchy Problem for Non-Strictly Hyperbolic Systems

“…the common denominator of the rational numbers <T (1) Thus we have proved that Z/$^) is a polynomial in H (x, (^i j) ), that is, (3.14)…”

Irregularity of Characteristic Elements and Hyperbolicity

“…Originally Levi's condition (7 = 1 was introduced as Condition C in Case I by E. E. Levi [23], A. Lax [20], M. Yamaguti [35], S. Mizohata-Y. Ohya [26] and J. Chazarain [2]. They proved that the Cauchy problem (17) is correctly posed in Q and S)' if Conditions A and B hold and if every real characteristic element is non-singular and of irregularity 1.…”

Light intensity distribution in conical refraction

“…Taylor showed in [7] that one can reduce microlocally the study of the boundary value problem for conical refraction to such an example. The double characteristic points are 2 …”