Halo White Dwarfs and Galactic Structure -- Old Ultracool White Dwarfs as Cosmological Probes -- Number Counts of White Dwarfs: The Impact of GAIA -- Influence of Metallicity in the Determination of the Age of Halo White Dwarfs -- Cool Halo White Dwarfs from GSCII -- Dark Halo Baryons not in Ancient White Dwarfs? -- The White Dwarf Population in the 2QZ and Sloan Surveys -- White Dwarfs and Cat…