sentences:  If, say, "X" is the blowup of "Y" at a point and "f" is the natural projection, then the relative dimension of "f" is zero except at the point which is blown up, where it is dim "Y" - 1.Some properties are said to hold "very generically".Frequently this means that the ground field is uncountable and that the property is true except on a countable union of proper Zariski-closed subsets (i.e., the property holds on a dense Gδ set).