Design and evaluation of scalable approaches to schedule a stream of batch jobs in large-scale grids

I think the grid computing stimulates the cooperation among people, that agree to share resources and knowledge, to address problems that are not reachable individually. The central purpose of grid computing is to enable a community of users to perform work on a pool of shared resources. Since the number of jobs to be done in most cases outnumbers the number of available resources, somebody must decide how to allocate resources to jobs. Historically, this has been known as the Scheduling Problem. A large amount of research in scheduling was motivated by the proliferation of massively parallel machines in the early 1990s, and the desire to use these very expensive resources as efficiently as possible. Nowadays, grid is the emerging computing platform. Grid computing makes the scheduling problem even more difficult since, due to its heterogeneous and highly distributed nature, it cannot be served by a single centralized scheduling framework. In this Thesis we propose the study conducted to design and evaluate a hierarchical framework to dynamically schedule a continuous stream of independent, batch jobs, on large-scale grids. Our scheduler aims to schedule arriving jobs respecting their computational requirements (hardware constraints, software resources needed to be executed, deadlines), and optimizing the utilization of hardware and software resources. We designed a lightweight Meta-Scheduler able to classify incoming jobs according to their relevance, and to schedule jobs among underlying resources balancing the workload among them. Furthermore, we designed different algorithms as Local-Schedulers, which are able to carry out the job machine associations using dynamic information about the environment. Eventually, the Thesis presents two important related results obtained by scientific collaborations. The former concerns to the study of the self-optimizing system behavior. The latter concerns to the comparison of one of our Local-Scheduler solution with a Schedule-Based algorithm proposed by Dalibor Klus´aˇcek and Hana Rudov´a of the University of Brno

Essays on empirical banking

The thesis is structured in three articles which develop microeconometric analysis on the Italian banking industry. The first two articles investigate, relying on different theoretical frameworks and techniques, the degree of competition in the retail segment whereas the third article examines the effects of relationship banking on firm innovativeness. The first article is entitled "Intensity of Competition and Market Structure in the Italian Banking Industry". The aim of this work is to empirically test Sutton’s predictions for industry with exogenous sunk costs in the Italian banking industry. In particular, I focus my attention only on the retail segment since products are rather standardized and there is a limited scope for cost-decreasing or quality increasing investments. The second article is entitled "Unit Roots and the Dynamic of Market Shares". In this article I rely on panel unit roots tests in order to infer the degree of competition in the industry. The main idea is to verify if market shares of the first five banks contain unit roots. If so, it is possible to infer that there is the chance for competitors to displace permanently the leader. On the contrary, if share are mean reverting, it is reasonable to infer that the industry is rather stable, and actors reached positions difficult to overcome. The third article is entitled "Relationship lending and Firm innovativeness: New Empirical Evidence". The aim of this study is to test the effect of firm-bank ties on the degree of firm innovativeness using data on a sample of Italian manufacturing firms. In particular, this article departs from previous microeconometric works since it distinguishes the discovery phase from the introduction phase of new technologies

Central v. local ownership of firms

This work analyses the presence of public shareholding in limited companies in European countries. Firms owned by public bodies (State or local authorities) can be found in many economic sectors. This type of governance stretches its influence beyond its traditional domains, including business areas in which competition is a common feature. In recent years these companies have changed in some cases their usual governance, including private shareholders alongside public entities: companies whose ownership is shared among public and private entities are often called mixed enterprises. The analysis not only focuses on public central ownership; it also presents and analyses the evidence of a strong local public shareholding in European enterprises. A very demanding and time consuming part of the work has been building a unique database, which has then been studied in its different facets. This database includes more than 5,600 EU companies with public shareholders; more than 40% of them are participated by local authorities. The data analyzed were collected from the official accounts of the same companies. The main results of the analysis can be summarized as follows. First, the descriptive statistics have shown that public ownership, both at central and local level, is widespread in Europe. Such ownership has however different degrees of importance across industries. Second, the analysis of the companies' financial figures has pointed out some clear differences between Western European Countries and Eastern European Countries. Despite undeniable progress, in many sectors Eastern European Countries firms still suffer from their starting point, inadequacy of the infrastructure and different degree of technological development. In the same way, we document and test the disparities between different sectors within the same Country and between the same sectors across Countries. For example, at European level the sector with the highest profitability appears to be finance (followed by communications), while the countries with the highest profitability appear to be Luxembourg followed by Estonia and Slovakia. A further analysis has compared the value added produced by companies where a public shareholder is present and the total values added of European regions. This has confirmed the remarkable relevance of the companies with public shareholdings on the economy of the countries considered, which amounts to an average value of 4.7% of the value added, which in some regions reaches 15%. This result remains true at the local level: enterprises with local public shareholders have a leading role in the GDP at the regional level. The Italian case, sometimes indicate as one where the public presence is pathologically high, does not stick out as something too different from what we observe in countries such as France, Germany or the Netherlands. Significant differences were found on the tests on averages and medians. through classifying the companies in the sample by shareholder type, by sector, by geographical area and by governmental from in the local area of reference. Finally, some regression tests were made to show that performance indicators were correlated with some enterprise characteristics - size, activity sector, shareholder type (central or local), and share percentage (total public v. partial public). For the latter we tested whether the institutional structure of the countries to which enterprises belong (federal Countries v. non-federal Countries) and public shareholder type could influence the performance of government-owned enterprises

Automatic context adaptation of fuzzy systems

Among the several applications of fuzzy set theory, fuzzy-rule based systems (FRBSs) have proven to be extremely successful in a wide range of fields, including, for instance, control, classification, regression, and pattern recognition. In particular, FRBSs have raised attention for their twofold nature, i.e., for their ability to handle linguistic concepts and, at the same time, to perform an accurate modeling of input-output relations. Hence, several researchers and practitioners have developed learning algorithms for the automatic identification of FRBSs from real-world data. Such algorithms include the hybridizations of FRBSs with other popular soft computing techniques, i.e., artificial neural networks and evolutionary algorithms. In this framework, context adaptation of fuzzy systems is considered as an emerging paradigm which has been analyzed only in a few works. In a nutshell, context adaptation consists in tuning some of the features of an already existing FRBS, so as to adapt it to a new configuration of the external environment. This task has usually been approached in the literature as scaling fuzzy sets from a universe of discourse to another. The basic idea presented here is to achieve context adaptation by exploiting a set of operators which allow performing a more flexible tuning than scaling-functionbased techniques, while keeping the semantics and the interpretability of the original FRBS unaltered. Nonetheless, this work collects previous approaches and organizes them in a common framework, thus providing a reference study on the topic. In the development of the thesis, we first recall fundamentals of fuzzy set theory, fuzzy logic, and fuzzy systems. We survey previous work on related subjects and introduce the context adaptation problem in detail. Second, we develop a novel context adaptation approach. To this aim, we introduce a flexible non linear scaling function and four orthogonal fuzzy modifiers which allow adapting an FRBS to any context. Since the modeling capabilities of the operators may negatively affect the semantics of the FRBS, we study two novel indices to properly measure interpretability and prevent such degradation. The proposed learning approach is based on evolutionary algorithms and takes both the flexibility introduced by the operators and the interpretability assessed by the indices into account. We test our context adaptation technique on four different data sets, providing detailed examples and comparisons. Finally, we draw concluding remarks and we discuss future extensions and possible research lines

Extending ontology queries with bayesian network reasoning

Today, ontologies are the standard for representing knowledge about concepts and relations among concepts concerning specific domains. In general, ontology languages are based on crisp logic and thus they can not handle incomplete or partial knowledge about application domain. However, uncertainty exists in domain modeling, ontology reasoning, and concept mapping. Our choice for dealing with uncertainty, is the Bayesian probability theory. The technique of representing an ontology by means of a bayesian network is used for having a new knowledge base enriched with uncertainty, over which making inference and probabilistic reasoning. Our method is composed of three steps. The first one is to compile the ontology into a bayesian network. We define the ontology compiling process for extracting the bayesian network structure directly from the schema of the knowledge base. The second one is to learn the initial probability distributions. We provide a computation process for learning the probability distributions, both prior and conditional, directly from the ontology instances, based on the Bayes theorem. The third one is to provide a bayesian query language for answering queries involving probabilities. Although evaluating bayesian networks is, in general, NP-hard, there is a class of networks that can efficiently be solved in time linear in the number of nodes. It is that of the polytree. On the basis of this bayesian network class, it is provided a bayesian query language for answering queries involving probabilities concerning both is - a ontology relations and object - property relations. It is based on recursive algorithms implementing top-down and bottom-up reasoning over polytrees networks

Politics behind globalization: the influence of political and security variables on economic interdependence among States

The dissertation investigates the influence of domestic and international politics on economic interdependence among states in the age of globalization. On the one hand it aims at updating the studies on the influence of political variables on international trade taking into consideration the post-Cold War years. On the other hand it aims at expanding the operational definition of economic interdependence performing the first empirical of the influence of politics on bilateral flows of FDI. Through an extensive use of panel data analysis, I find that both domestic and international politics have a relevant impact on economic interdependence even in the context of globalization. However, none of the classic theories of international relations on the causes and consequences of interdependence can fully explain the current dynamics. The system is increasingly complex and the realist and liberal seem to work together accounting for different phenomena that happen contemporaneously

Essays on the real effects of banking development and concentration

This thesis consists of three essays on the impact of banking development and concentration on the real economy. By looking at three specific mechanisms, this work supports the hypothesis that access to finance may be a barrier to entry and exit of firms. Furthermore, it provides empirical evidence of non-linearity in the relationship between banking market structure and the real economy. The three essays adopt the Rajan-Zingales (1998) methodology, which is especially useful for establishing a causal relationship between finance and real sector performance as well as for overcoming potential endogeneity problems. The first essay investigates the relationship between bank concentration and the real economy by analyzing the number and average size of firms in manufacturing industries in two samples of countries with differing levels of economic development. The main finding is that in developed countries a higher bank concentration is associated with a lower number of firms, of bigger size, while in developing countries this relationship does not seem significant. The second essay analyzes the effect of bank concentration on firm demography, conditional on the depth of credit markets. The empirical evidence on a sample of EU countries shows negative effects of bank concentration on firm demography when domestic the size of banking market is sufficiently large. This suggests that bank concentration in itself is not a barrier to entry and exit of firms. The third essay extends a recent cross-country study by Coricelli and Roland (2008) on the asymmetric effects of banking development on real economy performance, distinguishing periods of economic expansion from declines. Using data for Italy, this essay examines the issue at regional level and shows that more developed local credit markets are associated with lower declines in firm net entry rates

Three essays on the implemetation process of the Basel II capital accord

The aim of the thesis is to analyze the implementation process of Basel II so to understand whether and to what extent national discrepancies might cause problems of competitive neutrality and thus invalidate the significant level of harmonization in capital adequacy regulation which was successfully achieved by Basel I. To achieve this result, this work looks at three different issues. The first paper looks at the negotiation process of an international soft law agreement and tries to understand whether it is able to explain its implementation results in terms of the actual degree of compliance across different countries. A game theory coordination model is suggested as a theoretical answer to this question, while the two Basel Accord cases are used to test the model empirically. The appreciation of the circumstances that led to the two Accords is proved as indicative of the reasons behind the widespread adoption of the Basel I Accord as opposed to the piecemeal implementation of Basel II. The aim of the second paper is then focus on the actual implementation of Basel II and to analyze how its second Pillar is likely to impact the banking industry in Europe. It finds evidence of a piecemeal implementation of Pillar II rules across Member States (MSs) which, in turn, is able to cause an alteration of the level playing field among banks depending on the country they are incorporated in,. It concludes that there is a clear case for further harmonization not only by reducing the extent of national discretions at the regulatory level, but more importantly in building up further arrangements for supervisory convergence and coordination. With the third paper the attention is finally drawn to possible problems of competitive neutrality arising from the fact that under Basel II "standardized" banks' level of capital is indirectly determined by rating agencies. Being their predictions often inconsistent one with the other, banks can in principle enact regulatory arbitrage strategies. And despite minimum standards are required by means of a common recognition process, the consistency of national authorities' assessment is still not guaranteed and banks might thus be provided with undue regulatory capital relief. A more institutional answer is needed if Europe wants in real fact to ensure competitive neutrality across MSs

Essays on the effects of flexibility on labour market outcome

The thesis is structured in three articles which develop an analysis focused on the effects of labour market regulation on the labour market outcome and country economic performance. The first paper makes a review of literature by supporting the "OECD-IMF orthodoxy" according to which the rigidities imposed by labour market institutions are crucial determinants to explain European unemployment. Many works have been published which support this view. While these studies have become increasingly complex, the empirical results do not appear to be robust since they are highly sensitive to the nature of variables, the time period, and the econometric methods applied. Various reasons explain the adherence to this orthodoxy: the existence of priors, poor data on labour market institutions, as well as unsuitable econometric techniques. Considering that additional cross-country analysis will not be decisive to improve our understanding of labour market institutions, this paper suggests new investigations which rely on time-seriescross-section (TSCS) techniques, micro-analysis of firms and workers, as well as human subject and artificial experiments. The second paper delves into the relationship existing between labour market flexibility - epitomized by the proportion of temporary and part-time workers - and companies’ ability to innovate- as measured by the percentage of new products in total sales. Even though it is an important issue affecting a country economic growth, the analysis of the flexibility effects on companies’ innovativeness is almost neglected in current literature. On the one hand, ’more flexibility’ (i.e. a higher labour turnover) might foster firms’ innovation potential. Beside having (potential) wage savings effects, a larger inflow of new staff may enrich the pool of companies’ innovative ideas. On the other hand, greater work flexibility may have some drawbacks: steadily high rates of people entering and leaving firms may reduce social cohesion and trust, as well as increase the probability of opportunistic behaviour. Results suggest that a higher percentage of internal flexibility is associated with greater propensity to innovate, especially in high-tech firms. In line with the 1999/70/EC European directive, these results also suggest that fixed-term contracts (external flexibility) might be useful in periods of extraordinary corporate activity, but can have disadvantages for firms innovativeness and productivity if improperly used during normal activity. Finally, the third paper refers to one of the most attractive model for policymakers in Europe: the flexicurity model that combines elements of flexibility in labour markets with income and employment security for workers. Although common principles might drive labour market reforms, flexicurity should take up different forms from country to country. The aim of this work is investigate which is the suitable pathway for Italy and identify the advantages and risks of adopting lexicurity policies. In the first part, the paper examines flexicurity in Denmark, one of the leading country in this field, and then focuses on Italian labour market only. In particular, on the basis of an experimental analysis, the second part investigates the possibility for Italy to follow the first European flexicurity pathway which - in the case of countries with segmented labour markets - suggests to rely on contractual arrangements to distribute flexibility and security more evenly across the workforce. Unlike other experimental analysis, in this case the level of unemployment is determined endogenously and the level of efforts made is observable with a certain degree of uncertainty. This feature allows to study the interactions of labour market regulation and firms’ employment policy in determining the unemployment level. Results suggest that - especially in countries such as Italy, where there is limited scope for increasing spending - these contractual arrangements can improve the situation both for workers and companies