On the boundedness of pseudo differential operators in the class $L\sp{m}\sb{\rho }{}\sb{,1}.$
Luigi Rodino · Proceedings of the American Mathematical Society · 1976
We prove that every pseudo differential operator in the class L™,, 0 < p < 1, is bounded in L2(R") if and only if m < n(p -l)/2.According to Hörmander [3], we denote by S™s, 0 < p < 5 < 1, the class of the symbols a(x,i) G C°°(R" X R") which satisfy the inequalities: