Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2025/iii/paper-107/4/c/i/solution

For in the closed upper half-space, write . The boundary Simon absorption lemma has the following scaled form. Let be a nonnegative set functional that is monotone and subadditive on finite covers by such half-balls. Given and , there is such that, if and every admissible nested pair satisfies
then
The same conclusion holds for half-balls centred on the flat boundary and truncated balls meeting it. Iteration over a finite covering absorbs the small first term into the left-hand side.
Solved by gpt-5.6-sol high.

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