[1]
|
J. Barros-Neto and F. Cardoso, Gellerstedt and Laplace-Beltrami operators relative to a mixed signature metric, Ann. Mat. Pura Appl. 188 (2009), 497-515.
|
[2]
|
E. Beltrami, Saggio di interpretazione della geometria non-euclidea, Giornale di Matematiche 6 (1868), 284-312.
|
[3]
|
K. O. Friedrichs, Symmetric positive linear differential equations, Commun. Pure Appl. Math. 11 (1958), 333-418.
|
[4]
|
J. Heidmann, Relativistic Cosmology, An Introduction. Springer-Verlag, Berlin-Heidelberg-New York (1980).
|
[5]
|
M. V. Keldysh, On certain classes of elliptic equations with singularity on the boundary of the domain (Russian]), Dokl. Akad. Nauk SSSR 77 (1951), 181-183.
|
[6]
|
P. D. Lax and R. S. Phillips, Local boundary conditions for dissipative symmetric linear differential operators, Commun. Pure Appl. Math. 13 (1960), 427-455.
|
[7]
|
F. Lobo and P. Crawford, Time, closed timelike curves, and causality, in The Nature of Time: Geometry, Physics and Perception (NATO ARW), Proceedings of a conference held 21-24 May, 2002 at Tatranska Lomnica, Slovak Republic (eds. Rosolino Buccheri, Metod Saniga, and William Mark Stuckey). NATO Science Series II: Mathematics, Physics and Chemistry - Volume 95. Dordrecht/Boston/London: Kluwer Academic Publishers, 2003.
|
[8]
|
A. Marini and T. H. Otway, Nonlinear Hodge-Frobenius equations and the Hodge-Bäcklund transformation, Proc. R. Soc. Edinburgh 140A (2010), 787-819.
|
[9]
|
T. H. Otway, Nonlinear Hodge maps. J. Math. Phys. 41 (2000), 5745-5766.
|
[10]
|
T. H. Otway, Hodge equations with change of type, Ann. Mat. Pura Appl. 181 (2002), 437-452.
|
[11]
|
T. H. Otway, Harmonic fields on the projective disk and a problem in optics, J. Math. Phys. 46 (2005), 113501. (Erratum: J. Math. Phys. 48 (2007), 079901.)
|
[12]
|
T. H. Otway, Variational equations on mixed Riemannian-Lorentzian metrics, J. Geom. Phys. 58 (2008), 1043-1061.
|
[13]
|
T. H. Otway, The Dirichlet Problem for Elliptic-Hyperbolic Equations of Keldysh Type, Lecture Notes in Mathematics, Vol. 2043, Springer-Verlag, Berlin-Heidelberg-New York-Tokyo, 2012.
|
[14]
|
T. H. Otway, Elliptic-Hyperbolic Partial Differential Equations: a mini-course in geometric and quasilinear methods, Springer-Verlag, London, 2015.
|
[15]
|
L. Sarason, On weak and strong solutions of boundary value problems, Commun. Pure Appl. Math. 15 (1962), 237-288.
|
[16]
|
J. M. Stewart, Signature change, mixed problems and numerical relativity, Class. Quantum Grav. 18 (2001), 4983-4995.
|
[17]
|
J. Stillwell, Sources of Hyperbolic Geometry, Amer. Math. Soc., Providence, 1996.
|
[18]
|
W. J. van Stockum, The gravitational field of a distribution of particles rotating about an axis of symmetry, Proc. R. Soc. Edinburgh 57 (1937), 135-154.
|
[19]
|
F. J. Tipler, Rotating cylinders and the possibility of global causality violation, Phys. Rev. D9 (1974), 2203-2206.
|
[20]
|
C. G. Torre, The helically reduced wave equation as a symmetric positive system, J. Math. Phys. 44 (2003), 6223-6232.
|