Subhypergraph counts in extremal and random hypergraphs and the fractional <Emphasis Type="Italic">q</Emphasis>-independence

We study the extremal parameter N(n,m,H) which is the largest number of copies of a hypergraph H that can be formed of at most n vertices and m edges. Generalizing previous work of Alon (Isr. J. Math. 38:116–130, 1981), Friedgut and Kahn (Isr. J. Math. 105:251–256, 1998) and Janson, Oleszkiewicz and the third author (Isr. J. Math. 142:61–92, 2004), we obtain an asymptotic formula for N(n,m,H) which is strongly related to the solution α _q (H) of a linear programming problem, called here the fractional q-independence number of H. We observe that α _q (H) is a piecewise linear function of q and determine it explicitly for some ranges of q and some classes of H. As an application, we derive exponential bounds on the upper tail of the distribution of the number of copies of H in a random hypergraph.     

Regulation by disclosure: the case of internal control

In this paper we explore the use of disclosure as a regulatory tool, using as an illustration the current UK requirements regarding the disclosure of information about internal control. After discussing the broad concept of regulation by disclosure, we trace the evolution of concepts of internal control and its reporting, describing the background to the Turnbull guidance for directors on internal control reporting, the basis of current UK requirements. We then examine recent examples of internal control disclosures, identifying the range of ways in which they address the disclosure requirements and considering the possible impact of the disclosure requirements on corporate behaviour and on the audiences for disclosure. We conclude with some reflections on the disclosure life cycle. The paper contributes to the literature on disclosure by specifically considering the role of disclosure as a regulatory tool and by examining the nature of specific disclosures in an area of continuing interest, that of internal control.     

Separator-based data reduction for signed graph balancing

Polynomial-time data reduction is a classical approach to hard graph problems. Typically, particular small subgraphs are replaced by smaller gadgets. We generalize this approach to handle any small subgraph that has a small separator connecting it to the rest of the graph. The problem we study is the NP-hard Balanced Subgraph problem, which asks for a 2-coloring of a graph that minimizes the inconsistencies with given edge labels. It has applications in social networks, systems biology, and integrated circuit design. The data reduction scheme unifies and generalizes a number of previously known data reductions, and can be applied to a large number of graph problems where a coloring or a subset of the vertices is sought. To solve the instances that remain after reduction, we use a fixed-parameter algorithm based on iterative compression with a very effective heuristic speedup. Our implementation can solve biological real-world instances exactly for which previously only approximations were known. In addition, we present experimental results for financial networks and random networks.     

Birds of a Feather? The Effect of Organizational Value Congruence on the Relationship Between Ministries and Quangos

In this paper we investigate differences between the organizational values of ministries and semi-autonomous executive agencies (quangos) that operate at arms’ length. Quangos are expected to operate more business-like, hence they can be expected to value profitability and other NPM-related values higher than ministries. Value incongruence between quangos and ministries is hypothesized to decrease their level of trust. These hypotheses are tested, using combined data from two Dutch surveys (n = 324). The results confirm the expectations, although different types of quangos have different degrees of value (in)congruence, which may lead to variations in the quality of the relationship with their parent ministry.     

The <Emphasis Type="Italic">p</Emphasis>-maxian problem on block graphs

This paper deals with the p-maxian problem on block graphs with unit edge length. It is shown that the two points with maximum distance provide an optimal solution for the 2-maxian problem of block graphs except for K ₃. It can easily be extended to the p-maxian problem of block graphs. So we solve the p-maxian problem on block graphs in linear time.     

Soft Regionalism in Action: Examining Voluntary Regional Councils’ Structures,Processes and Programs

In the United States, the voluntary regional council is the dominant organizational form used by local, state and federal agencies to address regional issues. However, research addressing the details of their operations including their structures, processes and programs has been limited. This article reports on a survey of thirty of these regional councils that are located in large metropolitan areas. The findings indicate that these councils reflect a form of “soft regionalism.” Primarily, they facilitate, coordinate and energize, but they don’t have the more expansive capabilities of consolidations, regional governments and annexations.     

On the correlation between fraud and default risk

Identity fraud is one of the fastest growing white-collar crimes today and a serious concern in our information-based economy. This paper studies one type of identity fraud: new account fraud, where an impostor opens lines of credit using a false identity, made-up or stolen. Relying on a unique data set of consumer bank accounts, that contains information on both, fraud and default losses, I analyze the correlation between fraud and default risk. I find that common socio-economic/demographic account holder characteristics have opposite effects on estimated default and fraud probabilities. For example, women possess a lower fraud probability, but a higher default probability, compared to men, and foreigners are more likely to engage in account fraud but less likely to default than Germans. Also, the portfolio level analysis indicates that portfolio loss distributions are quite sensitive to ex ante portfolio characteristics like the share of foreigners or blue-collar workers. These findings have important implications for banks managing their consumer credit portfolios using limiting rules based on borrower characteristics, and for the adequacy of banks’ capital levels.     

A tighter formulation of the <Emphasis Type=Italic>p</Emphasis>-median problem

Given a set of clients and a set of potential sites for facilities, the p-median problem consists of opening a set of p sites and assigning each client to the closest open facility to it. It can be viewed as a variation of the uncapacitated facility location problem. We propose a new formulation of this problem by a mixed integer linear problem. We show that this formulation, while it has the same value by LP-relaxation, can be much more efficient than two previous formulations. The computational experiment performed on two sets of benchmark instances has showed that the efficiency of the standard branch-and-cut algorithm has been significantly improved. Finally, we explore the structure of the new formulation in order to derive reduction rules and to accelerate the LP-relaxation resolution.