Addendum to the article ``A remark on the stability problem in fluid dynamics'' (Q1119104)

In Theorem 1 [the authors, ibid. 128, 413-418 (1987; Zbl 0626.76056)] it was assumed \(| \nabla {\bar \omega}| >0\). This condition with the collinearity of \(\nabla \Psi\) and \(\nabla {\bar \omega}\) implies that the following condition is satisfied: (a) there exists a function F: \({\mathbb{R}}\to {\mathbb{R}}\), \(F\in C^ 1\), such that \(\Psi =F({\bar \omega})\). Actually, our theorem is true also if \(| \nabla {\bar \omega}| \geq 0\) and (a) is assumed. This enlarges the range of applicability of our theorem.