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The COVID-19 pandemic has exacerbated the asymmetric employment problems in the global services sector. Would a liberalization of the highly protected services trade between the rich and poorer countries help solve such problems? This paper contributes to answering that question by analyzing the impacts on welfare and employment of an hypothetical liberalization of the services trade between the Africa, Caribbean and Pacific Group of States (ACP) and their rich partners in the European Union and the United Kingdom (EU+UK). For both the ACP and EU +UK, their service sectors play important role in their economy, especially in providing jobs. The services sectors employ the majority of unskilled labor and the large majority of skilled labor. For instance, in the EU+UK, 67% of employed unskilled and 82% of employed skilled workers are in the service sectors; the respective figures for ACP countries are 54% and 90%. These figures indicate that any change in trade policies for the services sector will affect not just the services but also other sectors such agriculture and manufacturing in ACP and EU countries. To analyze the impacts of services trade liberalization on welfare an employment, I use a Computable General Equilibrium model that takes into account the labor productivity gaps among trading countries. Results show that although ACP services represents only about 24% of ACP's total exports to and 28% of ACP's total import from the EU+UK, halving the bilateral tariffs in services trade will generate for the ACP a welfare gain 3.4 times larger than the gain under elimination of bilateral tariffs on goods. Such liberalization of services trade will generate significant endowment effects equivalent to 410,000 new jobs per year, mostly in the services sector. The employment and welfare gains will also reach other sectors, including agriculture, as services trade costs are reduced. The liberalization of services trade will raise wages, especially for ACP's skilled labor. All these ACP's gains will increase further if its labor productivity improves. Despite a slight decline in wages for EU+UK's skilled labor, the EU+UK will gain about 7.8 billion USD in welfare. Overall, liberalization of the services trade between ACP and EU+UK will help solve their employment problems and should not be delayed.

Complex hardware systems become more and more ubiquitous in mission critical applications such as military, satellite, and medical to name but a few. In such applications, reliability remains a primary concern because a failure that occurs during their normal operations might produce important catastrophes like loss of life or loss of money. All these failures are often caused by minuscule bug that exists inside the software which controls the systems, or within the hardware itself. In addition, most of these systems cannot be interrupted while working, even for a few seconds a year, making it difficult to repair bugs found during their normal operations. The main purpose of this work is to build efficient verification techniques for asynchronous concurrent systems. Because of the pivotal roles these systems assume in a given application, designers of such systems must keep development and maintenance costs under control and meet nonfunctional constraints on the design of the system, such as cost, power, weight, or the system architecture by itself. But most importantly, they must assure their customer as well as the certification authorities that both the design and its implementation are correct. Otherwise, they may end up shipping unsafe systems to the market, and the consequences of this action would be catastrophic. To achieve this goal, designers need efficient methods and tools to assist them in verifying the correctness of the design. In this thesis we focus on a symbolic model checking technique called bounded model checking (BMC). BMC is a method targeted mainly at finding bugs in a system. It answers the questions whether there exists a counterexample, shorter than a given length, that violates a given property. During a BMC operation each execution path is encoded into Boolean formula, and the problem is reduced to satisfiability checking of the formula. Therefore, the operation consists mainly in constructing a Boolean formula that is satisfiable if and only if such a counterexample exists. We model our systems with transition systems (TSs). In particular, we are mainly interested in synchronized product of TSs. Since concurrent systems are formed by a combination of several components communicating between each other, synchronized product of TSs is well-suited to capture the behavior of such systems. The executions of concurrent systems are commonly modeled using the so-called interleaving execution, which allows only one single event to fire at each step. However, due to the complexity of such systems inteleaving method will not only require many steps but also generate long formulas. In this work, we adopt another approach based on breadth-first search (BFS). In a BMC operation, the translation of the model into a Boolean formula is polynomial in the size of the model, but the solving time of the Boolean formula can be exponential in the size of the formula. Therefore, our research hypothesis is that we can improve the efficiency of BMC by generating succinct formula, and by minimizing the number of necessary steps during an execution. We introduce several BMC techniques aimed at improving the efficiency of BMC for asynchronous concurrent systems. The techniques are grouped in two main parts (i) techniques for checking reachability properties and (ii) techniques for checking properties written in linear temporal logic (LTL). In addition, we also propose some methods for minimizing the number of execution steps or bound. We implemented all these methods in a BMC toolset. At the end of the dissertation, we will discuss the experimental results we obtained. ; Postprint (published version)

Complex hardware systems become more and more ubiquitous in mission critical applications such as military, satellite, and medical to name but a few. In such applications, reliability remains a primary concern because a failure that occurs during their normal operations might produce important catastrophes like loss of life or loss of money. All these failures are often caused by minuscule bug that exists inside the software which controls the systems, or within the hardware itself. In addition, most of these systems cannot be interrupted while working, even for a few seconds a year, making it difficult to repair bugs found during their normal operations. The main purpose of this work is to build efficient verification techniques for asynchronous concurrent systems. Because of the pivotal roles these systems assume in a given application, designers of such systems must keep development and maintenance costs under control and meet nonfunctional constraints on the design of the system, such as cost, power, weight, or the system architecture by itself. But most importantly, they must assure their customer as well as the certification authorities that both the design and its implementation are correct. Otherwise, they may end up shipping unsafe systems to the market, and the consequences of this action would be catastrophic. To achieve this goal, designers need efficient methods and tools to assist them in verifying the correctness of the design. In this thesis we focus on a symbolic model checking technique called bounded model checking (BMC). BMC is a method targeted mainly at finding bugs in a system. It answers the questions whether there exists a counterexample, shorter than a given length, that violates a given property. During a BMC operation each execution path is encoded into Boolean formula, and the problem is reduced to satisfiability checking of the formula. Therefore, the operation consists mainly in constructing a Boolean formula that is satisfiable if and only if such a counterexample exists. We model our systems with transition systems (TSs). In particular, we are mainly interested in synchronized product of TSs. Since concurrent systems are formed by a combination of several components communicating between each other, synchronized product of TSs is well-suited to capture the behavior of such systems. The executions of concurrent systems are commonly modeled using the so-called interleaving execution, which allows only one single event to fire at each step. However, due to the complexity of such systems inteleaving method will not only require many steps but also generate long formulas. In this work, we adopt another approach based on breadth-first search (BFS). In a BMC operation, the translation of the model into a Boolean formula is polynomial in the size of the model, but the solving time of the Boolean formula can be exponential in the size of the formula. Therefore, our research hypothesis is that we can improve the efficiency of BMC by generating succinct formula, and by minimizing the number of necessary steps during an execution. We introduce several BMC techniques aimed at improving the efficiency of BMC for asynchronous concurrent systems. The techniques are grouped in two main parts (i) techniques for checking reachability properties and (ii) techniques for checking properties written in linear temporal logic (LTL). In addition, we also propose some methods for minimizing the number of execution steps or bound. We implemented all these methods in a BMC toolset. At the end of the dissertation, we will discuss the experimental results we obtained. ; Postprint (published version)

Complex hardware systems become more and more ubiquitous in mission critical applications such as military, satellite, and medical to name but a few. In such applications, reliability remains a primary concern because a failure that occurs during their normal operations might produce important catastrophes like loss of life or loss of money. All these failures are often caused by minuscule bug that exists inside the software which controls the systems, or within the hardware itself. In addition, most of these systems cannot be interrupted while working, even for a few seconds a year, making it difficult to repair bugs found during their normal operations. The main purpose of this work is to build efficient verification techniques for asynchronous concurrent systems. Because of the pivotal roles these systems assume in a given application, designers of such systems must keep development and maintenance costs under control and meet nonfunctional constraints on the design of the system, such as cost, power, weight, or the system architecture by itself. But most importantly, they must assure their customer as well as the certification authorities that both the design and its implementation are correct. Otherwise, they may end up shipping unsafe systems to the market, and the consequences of this action would be catastrophic. To achieve this goal, designers need efficient methods and tools to assist them in verifying the correctness of the design. In this thesis we focus on a symbolic model checking technique called bounded model checking (BMC). BMC is a method targeted mainly at finding bugs in a system. It answers the questions whether there exists a counterexample, shorter than a given length, that violates a given property. During a BMC operation each execution path is encoded into Boolean formula, and the problem is reduced to satisfiability checking of the formula. Therefore, the operation consists mainly in constructing a Boolean formula that is satisfiable if and only if such a counterexample exists. We model ...

As many countries in Sub-Saharan Africa (SSA) struggle against severe food insecurity, unemployment and poverty, their heavy reliance on the export of raw materials as sources of revenue to solve these problems has long been put into question. The trade between China and SSA is characterized by China's importing mining and extraction from SSA and SSA's importing manufactured goods from China. We analyse the asymmetric SSA-China trade and focus on how trade policy and productivity shocks will reduce SSA's dependency on raw material export to China. We perform accounting and simulation exercises using the General Equilibrium GTAP model. The main innovation in our study is the inclusion of estimates of different labor productivity growth rates across regions and across sectors in the model. These labor productivity growth estimates show that the gaps between China and SSA especially in manufacturing are huge; ignoring these gaps would have biased any estimation. The other innovation is the simulation that the imports from China would yield some technology spillover on productivity in SSA. We examine several scenarios that include tariff elimination by China, common external tariff in SSA, and free regional trade in SSA. We find that with its current low labor productivity growth rates especially in manufacturing sectors, SSA continues to lose in the global trade, including in its trade with China. More important, manoeuvring room for trade policies is limited. China tariffs on imports from Africa are already low and bringing these tariffs down to zero will lead only to a modest increases in welfare and employment for SSA without altering SSA's dependence on raw material export. Raising the tariffs on manufactured goods from China will reduce SSA's welfare and employment by harming consumers and the agriculture sectors dependent on intermediate goods from China. Increases in labor productivity and technical progress in SSA's manufacturing sectors are welfare improving, but will not alter the high share of mining and extraction export to China unless such increases in productivity are accompanied by a voluntary restriction on these raw material exports. As such a voluntary restriction is being practically hard to apply and sustain, SSA shall continue to liberalize internal markets and pursue higher growth rates in labor productivity to cut the losses in international trade. Our simulations show that freer intra-African trade with small and steady increase in productivity can have significant impacts on welfare and employment.

This paper contributes to clarifying the scientific debate on whether off-farm activities hurt or help agricultural income in the Kerio Valley (Kenya). The main purpose of this research is to estimate the impacts of rural household's participation in regular off-farm activities on agricultural income. The literature indicates that off-farm activities affect rural household's income but studies on their effect on agricultural income have remained largely inconclusive. Determining how off farm activities affect agricultural income is highly relevant for the decisions of poor rural households and policy makers to allocate resources efficiently and increase investment to combat poverty. Investigation of the effects of regular off-farm activities is carried out in the following logical sequence: we performed surveys to gather information from rural households located in the Kerio Valley in Kenya; using the matching technique, we compared agricultural income per capita between households that took part in regular off-farm activities and those that did not. Methodological tools of the research were the results of a three-year project focusing on improving rural income. The object of research is the households in Kerio Valley in Kenya because they practiced the typical mix of farm and off-farm activities in rural Kenya. The empirical results of the analysis showed at first that household's participation in regular off-farm activities had no significant effect on household agricultural income per capita. However, by splitting agricultural income into crop and livestock incomes, we found that participation in regular off-farm activities did not affect crop income per capita but it increased livestock income per capita. The results can be useful to policy makers because it shows the existence of a symbiotic association between regular off-farm activities and livestock production. The results also confirm that creating opportunities for rural households to engage in off-farm activities generates supplemental revenues, and more importantly, reliable assets.
Keywords: matching technique, agricultural income, off-farm activities.

Insurance to deal with prolonged drought periods in rural Africa requires a practical method to estimate accurate premium values that minimize economic losses. We use non-parametric methods to determine the risk non-neutral insurer's premium for drought insurance on rain-fed crops. Premium values are estimated on the basis of percentage of the expected yield losses over the potential yields. Expected yield losses are estimated based on data on the levels of rainfall, potential evapotranspiration and water-holding capacity of the soil, and water requirement of the crop. Maize crop in West Kenya, and rice crop in the Central High Plains of Madagascar are taken as case studies. To check if farmer's choice of starting seasons affects the expected yields and the values of premium, we employ forecasted yields for two different sowing dates (October vs. November) for maize, and two different transplantation dates (November vs. December) for rice. The mean-variance (E-V), the First-Degree Stochastic Dominance (FSD), and the Second-Degree Stochastic Dominance (SSD) efficiency criteria are used to rank each pair of distributions. Results show that an insurer for maize production in Western Kenya would require a premium value between 43 and 55% of the potential yields to fully cover the loss caused by lack of rainfall. Under E-V and FSD, the two yield distributions cannot be ranked, but under SSD the yield distribution of the October-sown maize dominates that of November. For lowland rice in the Central High Plains of Madagascar, all three efficiency criteria indicate that the yield distribution of the December-transplanted rice dominates that of November and the premium values are less than 4 % of the potential yields.

"The potentially adverse effect of import surges on domestic markets and the agricultural sector, particularly in developing countries, have received enough attention to prompt the concepts of safeguards to protect against any "injurious" import surge. This book has two objectives. The first is to examine the theoretical and legal frameworks of an import surge, based on reviews of the definition and identification of an import surge, and its potential and likely effects. The second is to synthesize the findings of FAO country case studies, including implications for ways to deal with import surges, and especially to provide informed guidance to policy-makers to respond to the surge's consequences"--Publisher's description

AbstractThis analysis of food imports used an enhanced gravity model of trade, with food imports from approximately 136 countries from 2004 to 2014. Using improved panel data techniques, we show that total income, inflation in the food exporting country, corruption perception in the food exporting country, trade openness in the food exporting economy, GCC membership are important determinants of food imports by Qatar. In addition, we show that Qatari food imports mostly originate in countries with, on average, similar economic sizes. Finally, Qatar's factor endowment is dissimilar to those of most of its trading partners, a situation that potentially fosters international food trade in accordance with the Heckscher–Ohlin theory of trade.