New singular solutions of Protter's problem for the 3D wave equation

• M. K. Grammatikopoulos,
• N. I. Popivanov,
• T. P. Popov

Affiliations

M. K. Grammatikopoulos

Department of Mathematics, University of Ioannina, Ioannina 45110, Greece

N. I. Popivanov

Department of Mathematics and Informatics, University of Sofia, Sofia 1164, Bulgaria

T. P. Popov

Department of Mathematics and Informatics, University of Sofia, Sofia 1164, Bulgaria