基于理想解法的公司债券财务状况评价

本文详细介绍了如何基于理想解法建立公司债券财务状况的评价模型,并通过指标数据进行了实证分析,得到了比较满意的评价结果。     

Approximate factorizations with modified S/P consistently ordered M-factors

Preconditioned iterative methods are widely used to solve linear systems such as those arising from the finite element formulation of boundary value problems and approximate factorizations are widely used as preconditioners. The ordering of the unknowns is therefore an important issue because it has a strong influence on the convergence behaviour of the iteration method while it is also a decisive aspect for their parallel implementation. Consistent orderings are attractive for parallel implementations and it has been shown that some subclasses of these orderings also enhance the convergence behaviour of the associated iteration methods. This has in particular been shown for the so-called S/P consistent orderings. A wider definition of this class of orderings has recently been proposed and we investigate here how approximate factorizations should be implemented when using such more general orderings (still called S/P consistent) in order to keep their expected high convergence properties. A simple practical conclusion is suggested, supported by both theoretical and numerical arguments.     

Ordering distributions by scaled order statistics

Motivated by applications in reliability theory, we define a preordering (X ₁, ...,X _n) (Y ₁ ...,Y _n) of nonnegative random vectors by requiring thek-th order statistic ofa ₁ X ₁,..., a _n X _n to be stochastically smaller than thek-th order statistic ofa ₁ Y ₁, ...,a _n Y _n for all choices ofa _i >0,i=1, 2, ...,n. We identify a class of functionsM _{k, n} such that if and only ifE(X)E(Y) for allM _k,n. Some preservation results related to the ordering are obtained. Some applications of the results in reliability theory are given.Supported by the Air Force Office of Scientific Research, U.S.A.F., under Grant AFOSR-84-0205.     

ℱlow \mathcal{S} ort: a flow-based sorting method with limiting or central profiles

Based on the ranking methodology of PROMETHEE, a new sorting method (ℱlow ort) is proposed for assigning actions to completely ordered categories defined either by limiting profiles or by central profiles. The ℱlow ort assignment rules are based on the relative position of an action with respect to the reference profiles, in terms of the incoming, leaving, and/or net flows. For a better understanding of the issues involved, a graphical representation is given. An explicit relationship between the assignments obtained when working either with limiting or central profiles is formalized. Finally, an empirical comparison with Electre-Tri is made to compare the resulting assignments.      

Countably categorical coloured linear orders

In this paper, we give a classification of (finite or countable) ?₀‐categorical coloured linear orders, generalizing Rosenstein's characterization of ?₀‐categorical linear orderings. We show that they can all be built from coloured singletons by concatenation and ?_n‐combinations (for n ≥ 1). We give a method using coding trees to describe all structures in our list (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Universal cycles of -partitions of an -set

In 1992 Chung, Diaconis and Graham generalized de Bruijn cycles to other combinatorial families with universal cycles. Universal cycles have been investigated for permutations, partitions, k-partitions and k-subsets. In 1990 Hurlbert proved that there exists at least one Ucycle of n−1-partitions of an n-set when n is odd and conjectured that when n is even, they do not exist. Herein we prove Hurlbert’s conjecture by establishing algebraic necessary and sufficient conditions for the existence of these Ucycles. We enumerate all such Ucycles for n≤13 and give a lower bound on the total number for all n. Additionally we give ranking and unranking formulae. Finally we discuss the structures of the various solutions.     

一个基于模糊偏好的选择函数

研究了一个基于模糊偏好关系的模糊选择函数。首先对文献中基于普通关系的最好元集所确定的选择函数进行了回顾,并给出了进一步结果。然后,讨论了该选择函数的模糊化形式,给出了基于模糊偏好的选择集确定模糊选择函数的充要条件,同时研究了该选择函数的合理性性质。     

Sparse connectivity certificates via MA orderings in graphs

For an undirected multigraph G=(V,E), let α be a positive integer weight function on V. For a positive integer k, G is called (k,α)-connected if any two vertices u,v∈V remain connected after removal of any pair (Z,E^′) of a vertex subset Z⊆V-{u,v} and an edge subset E^′⊆E such that ∑_v∈Zα(v)+|E^′|<k. The (k,α)-connectivity is an extension of several common generalizations of edge-connectivity and vertex-connectivity. Given a (k,α)-connected graph G, we show that a (k,α)-connected spanning subgraph of G with O(k|V|) edges can be found in linear time by using MA orderings. We also show that properties on removal cycles and preservation of minimum cuts can be extended in the (k,α)-connectivity.