Note on a paper of N. Iwasaki
type: Item
instance of: scholarly article
title: Note on a paper of N. Iwasaki
zbMATH Open document ID: 0939.35111
author: Tatsuo Nishitani
published in: Journal of Mathematics of Kyoto University
publication date: 2000-07-05T00:00:00Z
review text: Let \(p(x,\xi)= \Pi j=1^mq_j(x,\xi)\) be a polynomial of \(\xi\), where \(q_j(x,\xi)\) are real valued pseudo-differential symbols of order one and \(z=(x,\xi)= (x_1,\dots, x_n,\xi_1,\dots, \xi_n)\), and assume that \(q_j\) are non-involutive w.r.t. each other. Then a triplet \((q_j,q_k,q_l)\) at a triple characteristic point has a signature. In this note the author show that when \(m=3\) the condition \(\text{sgn}(q_1, q_2,q_3)=-1\) is equivalent to that the propagation cone at a triple characteristic point is transversal to the double characteristic set. When in \(m>3\) an order relation on the set \(\{q_1, \dots, q_m\}\) can be induced, he gives another formulation of the condition that the propagation cone at every multiple characteristic point intersects transversally to the double characteristic set.
reviewed by: Kunihiko Kajitani
Mathematics Subject Classification ID: 35L25
zbMATH DE Number: 1309651
zbMATH Keywords: triple characteristic point
zbMATH Keywords: propagation cone
MaRDI profile type: Publication
full work available at URL: https://doi.org/10.1215/kjm/1250518057
OpenAlex ID: W1568385619
DOI: 10.1215/KJM/1250518057
description: scientific article; zbMATH DE number 1309651