Tatsuo Nishitani – författare
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4 produkter
4 produkter
Del 2097 - Lecture Notes in Mathematics
Hyperbolic Systems with Analytic Coefficients
Well-posedness of the Cauchy Problem
Häftad, Engelska, 2013
542 kr
Skickas inom 10-15 vardagar
With regard to sufficient conditions for (B), we introduce hyperbolic systems with nondegenerate characteristics, which contain strictly hyperbolic systems, and prove that the Cauchy problem for hyperbolic systems with nondegenerate characteristics is well posed for any lower order term.
Del 2202 - Lecture Notes in Mathematics
Cauchy Problem for Differential Operators with Double Characteristics
Non-Effectively Hyperbolic Characteristics
Häftad, Engelska, 2017
542 kr
Skickas inom 10-15 vardagar
Combining geometrical and microlocal tools, this monograph gives detailed proofs of many well/ill-posed results related to the Cauchy problem for differential operators with non-effectively hyperbolic double characteristics. Previously scattered over numerous different publications, the results are presented from the viewpoint that the Hamilton map and the geometry of bicharacteristics completely characterizes the well/ill-posedness of the Cauchy problem.A doubly characteristic point of a differential operator P of order m (i.e. one where Pm = dPm = 0) is effectively hyperbolic if the Hamilton map FPm has real non-zero eigen values. When the characteristics are at most double and every double characteristic is effectively hyperbolic, the Cauchy problem for P can be solved for arbitrary lower order terms.If there is a non-effectively hyperbolic characteristic, solvability requires the subprincipal symbol of P to lie between −Pµj and Pµj, where iµj are the positive imaginary eigenvalues of FPm . Moreover, if 0 is an eigenvalue of FPm with corresponding 4 × 4 Jordan block, the spectral structure of FPm is insufficient to determine whether the Cauchy problem is well-posed and the behavior of bicharacteristics near the doubly characteristic manifold plays a crucial role.
Del 1505 - Lecture Notes in Mathematics
Hyperbolic Cauchy Problem
Häftad, Engelska, 1991
274 kr
Skickas inom 10-15 vardagar
The approach to the Cauchy problem taken here by the authors is based on the use of Fourier integral operators with a complex-valued phase function, which is a time function chosen suitably according to the geometry of the multiple characteristics. The correctness of the Cauchy problem in the Gevrey classes for operators with hyperbolic principal part is shown in the first section of the text. In the second section, the correctness of the Cauchy problem for effectively hyperbolic operators is proved with a precise estimate of the loss derivatives. This method can be applied to other (non) hyperbolic problems. The text is based on a course of lectures given for graduate students but will be of interest to researchers interested in hyperbolic partial differential equations. In the latter part, the reader is expected to be familiar with the theory of pseudo-differential operators.
Del 30 - Mathematical Society Of Japan Memoirs
Cauchy Problem For Noneffectively Hyperbolic Operators
Häftad, Engelska, 2014
314 kr
Skickas inom 11-20 vardagar
At a double characteristic point of a differential operator with real characteristics, the linearization of the Hamilton vector field of the principal symbol is called the Hamilton map and according to either the Hamilton map has non-zero real eigenvalues or not, the operator is said to be effectively hyperbolic or noneffectively hyperbolic.For noneffectively hyperbolic operators, it was proved in the late of 1970s that for the Cauchy problem to be C∞ well posed the subprincipal symbol has to be real and bounded, in modulus, by the sum of modulus of pure imaginary eigenvalues of the Hamilton map.It has been recognized that what is crucial to the C∞ well-posedness is not only the Hamilton map but also the behavior of orbits of the Hamilton flow near the double characteristic manifold and the Hamilton map itself is not enough to determine completely the behavior of orbits of the flow. Strikingly enough, if there is an orbit of the Hamilton flow which lands tangentially on the double characteristic manifold then the Cauchy problem is not C∞ well posed even though the Levi condition is satisfied, only well posed in much smaller function spaces, the Gevrey class of order 1 ≤ s < 5 and not well posed in the Gevrey class of order s > 5.In this lecture, we provide a general picture of the Cauchy problem for noneffectively hyperbolic operators, from the view point that the Hamilton map and the geometry of orbits of the Hamilton flow completely characterizes the well/not well-posedness of the Cauchy problem, exposing well/not well-posed results of the Cauchy problem with detailed proofs.Published by Mathematical Society of Japan and distributed by World Scientific Publishing Co. for all markets