The present paper is a continuation of [1]. We continue the numbering of sections, assertions, remarks, and formulas in [1].
THE EXISTENCE OF STRONG SOLUTIONSThe solvability of the boundary value problems (1), (2) in the strong sense for all f ∈F −(m−1) is justified in the following assertion.
Theorem 2. Let the assumptions of Theorem1 in [1] and Conditions II and IV be satisfied, and let d j A −1Proof. Since the a priori estimates (28) imply that the ranges R L m (λ m ) of the operators L m (λ m ) are closed inF −(m−1) , it follows that, to justify the solvability of the boundary value problems (1), (2) in the strong sense for all f ∈F −(m−1) , it suffices to show that the ranges R (L m (λ m )) of the operators L m (λ m ) are dense inF −(m−1) . Since the spacesF −(m−1) are reflexive, it suffices to show that v = 0 wheneverfor some function v ∈Ê m−1 . Identities (37) admit (m − 1)-fold integration by parts:By passing to the limit, we generalize the last identities to all u ∈ H such that d m+1 u/dt m+1 , A s (t)d [(s+1)/2] u/dt [(s+1)/2] ∈ H , s= 0, . . . , 2m − 1, d k u/dt k ∈ H m−k , k = 1, . . . , m,