We study separable metric spaces with few types of countable dense sets. We present a structure theorem for locally compact spaces having precisely n types of countable dense sets: such a space contains a subset S of size at most n−1 such that S is invariant under all homeomorphisms of X and X \ S is countable dense homogeneous. We prove that every Borel space having fewer than c types of count...

The apparent restriction of the Diego blood factor to the Mongoloid peoples (Leyrisse and Arends, ’56) has provided the anthropologist with a tool of great potential usefulness in the evaluation of populations of mixed origin. In order to use this system to its full advantage, it is necessary to have considerable information on groups whose origin can with considerable certainty be labelled “mo...

In Berend and Kontorovich (2012), the following problem was studied: A random sample of size t is taken from a world (i.e., probability space) of size n; bound the expected value of the probability of the set of elements not appearing in the sample (unseen mass) in terms of t and n. Here we study the same problem, where the world may be countably infinite, and the probability measure on it is r...

The designation B4 is proposed for a weak variant of type B blood found in a Salvadorian woman and her two daughters. The red cells were weakly agglutinated by anti-B and anti-A,B; the serum contained anti-B; and the saliva contained H but not B substance. Biochemical studies of the serum showed that the enzyme specified by the variant B gene had low activity and low affinity for both sugar don...

A collection of Il 3-cube decompositions of a graph G is said to have intersection size t if there is a set S, with 181 = t, of 3-cubes which is contained in every decomposition, and no 3-cube which is not in S occurs in more than one decomposition. We determine all integers n, t and Il, with Il ::; 12, for which there exists a collection of Il 3-cube decompositions of Kn with intersection size...

98 Mexican Indians were tested for the blood properties A-B-O, A(1)-A(2), M-N, P, Rh'-Rh''-Rh(0)-rh, and Hr. Of the 98 Indians, 90.8 per cent belonged to group 0, 6.1 per cent belonged to A(1), and 3.1 per cent to group B. There were 61.2 per cent of type M, 3.1 per cent of type N, and 35.7 per cent of type MN. Of the 95 Mexican Indians tested with anti-P serum, 21.1 per cent were found to lack...