Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2012/iii/paper-31/1/v/solution

For , the correlation function of a point process associated with the eigenvalues is
The factorial factor counts ordered selections of distinct eigenvalues, so this is a factorial moment density, rather than the ordinary probability density of particular labels. Equivalently, for a nonnegative measurable test function ,
Repeated projection kernel determinant integration, with , gives a factor on integrating an -by- kernel determinant down to size . Together with the normalizing in , the factors cancel:
In particular and . Set and for . The eigenvalue configuration is thus a determinantal point process with a rank- finite-rank projection kernel.

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