REGULARITY-PROPERTIES OF THE SOLUTION OF THE HOMOGENEOUS WAVE-EQUATION

The aim of this paper is to prove regularity-properties for solutions of the wave equation in B-pq(s) with p < 1. Up to now no such result i s known. For p greater than or equal to 1 a large amount of work has b een done, cf. for instance [9], [7], [8], [10]. The results in this pa per for p > 1 are not optimal, which can be seen comparing them with [ 9]. Whether or not our results are optimal for p less than or equal to 1 is open.