Solution

ID: past-exam-of-the-mathematics-course-of-the-year-2-of-the-natural-sciences-course-of-the-university-of-cambridge/2010/paper-2/1/ii/solution

The appropriate weighted inner product and Sturm-Liouville operator are
For two functions obeying the endpoint conditions, integration by parts gives the Lagrange identity for a Sturm-Liouville operator
At , both and vanish. At , the factor tends to zero while the functions and their first derivatives remain bounded. Thus the boundary form vanishes at both ends.
This gives the regular self-adjoint differential operator realization: its singular-end condition is , together with . The bounded classical eigenfunctions satisfy exactly this no-log choice. More precisely the operator domain is the maximal differential-operator domain in the weighted space with these separated endpoint conditions; the preceding calculation verifies its self-adjoint boundary form, rather than merely the differential expression's formal symmetry.

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