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On the $$L_w^2$$-solutions to general second-order nonsymmetric differential equations. (English. Russian original) Zbl 0973.34027
Sib. Math. J. 42, No. 1, 181-189 (2001); translation from Sib. Mat. Zh. 42, No. 1, 202-211 (2001).
The authors extend the results by R. J. Amos [Questions Math. 3, 53-65 (1978; Zbl 0411.34041)] and F. V. Atkinson, W. D. Evans [Math. Z. 127, 323-332 (1972; Zbl 0226.34026)] to the case in which $$M$$ is a general second-order nonsymmetric operator. R. Amos proved that all solutions to the second-order differential equation $$M[y] = \lambda wy$$, $$\lambda\in\mathbb C$$, belong to $$L_w^2(a,\infty)$$ whenever $$M$$ is a second-order symmetric differential expression of the form $$M[f] = - (pf')' + qf$$ on $$[a,\infty)$$ under fulfillment of suitable conditions on the coefficients $$p$$ and $$q$$. F. Atkinson and W. Evans studied the case in which there are solutions that do not belong to $$L_w^2(a,\infty)$$.
The aim of the article under review is to study the $$L_w^2$$-solutions to general second-order nonsymmetric differential equations $$M[f] = \lambda wf$$ and $$M^+[g] = \overline\lambda wg$$, with $\begin{gathered} M[f] = - (p(f' - rf))' + up(f' - rf) + qf, \\ M^+[g] = - (p(g' + uf))' + rp(p' + uf) + qg. \end{gathered}$ Here, $$p$$, $$r$$, $$u$$, $$q$$ are complex-valued Lebesgue-measurable functions on the interval $$[a,b)$$, $$-\infty < a < b\leq \infty$$, satisfying the conditions $p(x)\neq 0\quad\text{for a.e. } x\in [a,b),\quad \frac{1}{p}, r, u, q\in L_{\text{loc}}(a,b) .$
##### MSC:
 34C11 Growth and boundedness of solutions to ordinary differential equations 34L40 Particular ordinary differential operators (Dirac, one-dimensional Schrödinger, etc.) 34B24 Sturm-Liouville theory
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