YUJIRO OHYA
MATHEMATICA JAPONICA Vol36 No. 3 591-601 1991年5月
The Caudhy problem for ∂2t+a(t,x)|D|Where a (t,x)≧0 will be discussed. In particular, the necessary and sufficient condition for the Cauchy problem of ∂2t+t2k|D|+αtυ|D|2/1to be wellposed was obtained.