منابع مشابه
The Number of Hierarchical Orderings
An ordered set-partition (or preferential arrangement) of n labeled elements represents a single “hierarchy”; these are enumerated by the ordered Bell numbers. In this note we determine the number of “hierarchical orderings” or “societies”, where the n elements are first partitioned into m ≤ n subsets and a hierarchy is specified for each subset. We also consider the unlabeled case, where the o...
متن کاملOn the Number of Radial Orderings of Planar
Given a set S of n points in the plane, a radial ordering of S with respect to a point p (not in S) is a clockwise circular ordering of the elements in S by angle around p. If S is two-colored, a colored radial ordering is a radial ordering of S in which only the colors of the points are considered. In this paper, we obtain bounds on the number of distinct non-colored and colored radial orderin...
متن کاملOn the number of radial orderings of planar point sets
Let S be a set of n points in general position on the plane. For a given point p not in S, a radial ordering of S with respect to p is a circular ordering of the elements of S by angle around p. If S is bi-colored, with equal sized color classes, then a colored radial ordering of S with respect to p is a circular ordering by angle of the colors of the points of S around p, that is, permutations...
متن کاملWell-partial-orderings and the big Veblen number
In this article we characterize a countable ordinal known as the big Veblen number in terms of natural well-partially ordered tree-like structures. To this end, we consider generalized trees where the immediate subtrees are grouped in pairs with address-like objects. Motivated by natural ordering properties, extracted from the standard notations for the big Veblen number, we investigate differe...
متن کاملthe effect of taftan pozzolan on the compressive strength of concrete in the environmental conditions of oman sea (chabahar port)
cement is an essential ingredient in the concrete buildings. for production of cement considerable amount of fossil fuel and electrical energy is consumed. on the other hand for generating one tone of portland cement, nearly one ton of carbon dioxide is released. it shows that 7 percent of the total released carbon dioxide in the world relates to the cement industry. considering ecological issu...
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ژورنال
عنوان ژورنال: Discrete Applied Mathematics
سال: 1996
ISSN: 0166-218X
DOI: 10.1016/0166-218x(96)00093-5