Laguerre series Laplace transform Lévy processes Mathematics & science Padé approximations Parisian ruin Pollaczek–Khinchine formula Research & information: general Segerdahl process Sparre Andersen model Tricomi–Weeks Laplace inversion adjustment coefficient affine coefficients bankruptcy barrier strategies boundary-value problem capital injection constraint capital injections capital surplus process completely monotone distributions de Finetti valuation objective diffusion-type process dividend payment dividends drawdown drawdown process error bounds first crossing time first hitting time first passage