Given a set S of 2n points in R d , a perfect matching of S is a set of n edges such that each point of S is a vertex of exactly one edge. The weight of a perfect matching is the sum of the Euclidean lengths of all edges. Rao and Smith have recently shown that there is a constant r > 1, that only depends on the dimension d, such that a perfect matching whose weight is less than or equal to r ti...

This article examines the geographical corridors for the establishment of rice in seventeenth-century Dutch Guiana. One corridor of introduction is associated with the expulsion of Dutch planters from Brazil in 1644, whose slaves reestablished longstanding subsistence preferences with their exodus to the colony. Another corridor links its introduction to the African Gold Coast, where rice devel...

An (N ;n,m, {w1, . . . , wt})-separating hash family is a set H of N functions h : X −→ Y with |X| = n, |Y | = m, t ≥ 2 having the following property. For any pairwise disjoint subsets C1, . . . , Ct ⊆ X with |Ci| = wi, i = 1, . . . , t, there exists at least one function h ∈ H such that h(C1), h(C2), . . . , h(Ct) are pairwise disjoint. Separating hash families generalize many known combinator...

the portfolio is a perfect combination of stock or assets, which an investor buys them. the objective of the portfolio is to divide the investment risk among several shares. using non-parametric dea and dea-r methods can be of great significance in estimating portfolio. in the present paper, the efficient portfolio is estimated by using non-radial dea and dea-r models. by proposing non-radial m...

I demonstrate that a consistent interpretation of Reichenbach’s (1947) primitives and their configurations enables the construction of an intuitive and elegant semantic space for all logically possible tense meanings, independent of their mode of expression. I argue that the property which defines the perfect in absolute tense systems is the dissociation of the temporal location of the situatio...

Extending the notion of (random) k-out graphs, we consider when the k-out hypergraph is likely to have a perfect fractional matching. In particular, we show that for each r there is a k = k(r) such that the k-out r-uniform hypergraph on n vertices has a perfect fractional matching with high probability (i.e., with probability tending to 1 as n → ∞) and prove an analogous result for r-uniform r-...

We study the classical and quantum models of a Friedmann-Robertson-Walker (FRW) cosmology coupled to a perfect fluid in the context of f(R) gravity. We use the Schutz’ variational formalism for the perfect fluid and show that it leads to a time parameter for the corresponding dynamical system. This formalism gives rise to a Schrödinger-Wheeler-DeWitt (SWD) equation for the quantum cosmology of ...

Let c(F) be the number of perfect pairs of F and c(G) be the maximum of c(F) over all (near-) one-factorizations F of G. Wagner showed that for odd n, c(Kn) ≥ n∗φ(n) 2 and for m and n which are odd and co-prime to each other, c(Kmn) ≥ 2 ∗ c(Km) ∗ c(Kn). In this note, we establish that both these results are equivalent in the sense that they both give rise to the same lower bound.