We will review some of the major results in random graphs and some of the more challenging open problems. We will cover algorithmic and structural questions. We will touch on newer models, including those related to the WWW.

Random graphs

In this paper recent developments in the estimation of frontier functions and the measurement of efficiency are surveyed, and the potential applicability of these methods in agricultural economics is discussed. Frontier production, cost and profit functions are discussed, along with the construction of technical, allocative, scale and overall efficiency measures relative to these estimated frontiers. The two primary methods of frontier estimation, econometric and linear programming, are compared. A survey of recent applications of frontier methods in agriculture is also provided. (This abstract was borrowed from another version of this item.)

Recent Developments in Frontier Modelling and Efficiency Measurement

Nonparametric estimators are widely used to estimate the productive efficiency of firms and other organizations, but often without any attempt to make statistical inference. Recent work has provided statistical properties of these estimators as well as methods for making statistical inference, and a link between frontier estimation and extreme value theory has been established. New estimators that avoid many of the problems inherent with traditional efficiency estimators have also been developed; these new estimators are robust with respect to outliers and avoid the well-known curse of dimensionality. Statistical properties, including asymptotic distributions, of the new estimators have been uncovered. Finally, several approaches exist for introducing environmental variables into production models; both two-stage approaches, in which estimated efficiencies are regressed on environmental variables, and conditional efficiency measures, as well as the underlying assumptions required for either approach, are examined. (This abstract was borrowed from another version of this item.)

Estimation and Inference in Nonparametric Frontier Models: Recent Developments and Perspectives

Centroidal Voronoi tessellations (CVTs) are Voronoi tessellations of a bounded geometric domain such that the generating points of the tessellations are also the centroids (mass centers) of the corresponding Voronoi regions with respect to a given density function. Centroidal Voronoi tessellations may also be defined in more abstract and more general settings. Due to the natural optimization properties enjoyed by CVTs, they have many applications in diverse fields. The Lloyd algorithm is one of the most popular iterative schemes for computing the CVTs but its theoretical analysis is far from complete. In this paper, some new analytical results on the local and global convergence of the Lloyd algorithm are presented. These results are derived through careful utilization of the optimization properties shared by CVTs. Numerical experiments are also provided to substantiate the theoretical analysis.

/pdf/convergence-of-the-lloyd-algorithm-for-computing-centroidal-3znr5a4sma.pdf

Convergence of the Lloyd Algorithm for Computing Centroidal Voronoi Tessellations

Linear Statistical Models: An Applied Approach.

https://repositorio.uac.pt/bitstream/10400.3/2143/1/ITOR04.pdf

Multi-outlet retail site location assessment

In social network analysis, a k-clique is a relaxed clique, i.e., a k-clique is a quasi-complete sub-graph. A k-clique in a graph is a sub-graph where the distance between any two vertices is no greater than k. The visualization of a small number of vertices can be easily performed in a graph. However, when the number of vertices and edges increases the visualization becomes incomprehensible. In this paper, we propose a new graph mining approach based on k-cliques. The concept of relaxed clique is extended to the whole graph, to achieve a general view, by covering the network with k-cliques. The sequence of k-clique covers is presented, combining small world concepts with community structure components. Computational results and examples are presented.

/pdf/an-algorithm-to-discover-the-k-clique-cover-in-networks-vmgirs16re.pdf

An Algorithm to Discover the k-Clique Cover in Networks

14th Portuguese Conference on Artificial Intelligence, EPIA 2009, Aveiro, Portugal, October 12-15, 2009.

/pdf/an-algorithm-to-discover-the-k-clique-cover-in-networks-4afhp1myrm.pdf

An Algorithm to Discover the k-Clique Cover in Networks.

Part I Efficiency Measures and Methods 1 Efficiency Measures in the Agricultural Sector: The Beginning Emiliana Silva, Armando Mendes and Jorge Santos 2 Review of Frontier Models and Efficiency Analysis: A Parametric Approach Ana Sampaio 3 Introduction to Data Envelopment Analysis Jorge Santos, Elsa Rosario Negas and Luis Cavique Santos 4 Superefficiency and Multiplier Adjustment in Data Envelopment Analysis Jorge Santos, Luis Cavique Santos, Armando Mendes Part II Farm Efficiency Applications 5 An Application of Data Envelopment Analysis (DEA) in Azores Dairy Farms Emiliana Silva, Amilcar Arzubi and Julio Berbel 6 Animal Grazing System Efficiency Emiliana Silva, Carlos Santos and Armando Mendes 7 Technical Efficiency of the Spanish Dairy Processing Industry: Do Size and Exporting Matter? Magdalena Kapelko and Alfons Oude Lansink 8 Inefficiency in Animal Production - A Parametric Approach Emiliana Silva and Fatima Venancio 9 Azorean Agriculture Efficiency by PAR Armando B Mendes, Veska Noncheva and Emiliana Silva 10 Sustainable Tourism and Agriculture Multifunctionality by PAR: A Variable Selection Approach Armando Mendes, Veska Noncheva and Emiliana Silva 11 The Importance of Subsidies in Azorean Dairy Farms Efficiency Emiliana Silva and Eusebio Marote 12 Multi-Ouput Technical Efficiency in the Olive Oil Industry and its Relation to the Form of Business Organisation Rafaela Dios-Palomares, Jose M. Martinez-Paz and Angel Prieto 13 Efficiency Assessment: Final Remarks Jorge Santos, Emiliana Silva and Armando Mendes Index

/pdf/efficiency-measures-in-the-agricultural-sector-with-33x7elqqyl.pdf

Efficiency Measures in the Agricultural Sector: With Applications

https://repositorio.uac.pt/bitstream/10400.3/2145/1/JRCS04.pdf

Armando B. Mendes

Papers

Multi-outlet retail site location assessment

An Algorithm to Discover the k-Clique Cover in Networks

An Algorithm to Discover the k-Clique Cover in Networks.

Efficiency Measures in the Agricultural Sector: With Applications

Clustering supermarkets: the role of experts