Discussion on the paper by Friedman and Fisher

Boswell, S. B. (1983) Nonparametric Mode Estimation for Higher Dimensional Densities. Ph.D.thesis, Department of Mathe-matical Sciences, Rice University. Good, I. J. and Gaskins, R. A. (1980) Density estimation and bump-hunting by the penalized likelihood method exempli-fied by the scattering and meteorite data (with discussion). Journal of American Statistical Association, 75, 42–73. Scott, D. W. (1992) Multivariate Density Estimation: Theory, Practice, and Visualization. Wiley, New York.