From Bilateral Trade to Centralized Markets: A Search Model for Commodity Exchanges in Africa

“From Bilateral Trade to Centralized Markets: A Search Model for Commodity Exchanges in Africa,” with Pellegrina, H. S., (2021).

Several African countries have recently centralized their agricultural markets by launching a commodity exchange. What will be the impact of such a move? Who will be the winners and the losers? We develop a simple search model to study the impact of introducing a commodity exchange in a village economy where traders and farmers exchange on a bilateral basis. We study the efficiency gains from moving from the status quo to a trading regime where farmers have the option of selling their produce to a commodity exchange. We describe how the gains from trade are distributed between farmers, traders and the commodity exchange itself. We show that a dual economy where farmers sell both to the bilateral and the commodity exchange can exist in equilibrium, and that forcing all farmers to sell into the commodity exchange can make some farmers worse off.

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World Bank Economic Review, Vol. 31, No. 3

Nyarko, Y. (co-editor). The World Bank Economic Review. Number 3, Volume 31, (2017) Oxford University Press.

What Is Considered Development Economics? Commonalities and Differences in University Courses around the Developing World - David McKenzie and Anna Luisa Paffhausen

Does Financial Education Impact Financial Literacy and Financial Behavior, and If So, When? -Tim Kaiser and Lukas Menkhoff

A First Step up the Energy Ladder? Low Cost Solar Kits and Household’s Welfare in Rural Rwanda -Michael Grimm, Anicet Munyehirwe, Jörg Peters, and Maximiliane Sievert

The Cost of Fear: The Welfare Effect of the Risk of Violence in Northern Uganda - Marc Rockmore

Identifying Gazelles: Expert Panels vs. Surveys as a Means to Identify Firms with Rapid Growth Potential -Marcel Fafchamps and Christopher Woodruff

On Minimizing the Risk of Bias in Randomized Controlled Trials in Economics - Alex Eble, Peter Boone, and Diana Elbourne

Donor Competition for Aid Impact, and Aid Fragmentation - Kurt Annen and Luc Moers

The Impacts of India’s Food Security Policies on South Asian Wheat and Rice Markets - Nelson Benjamin Villoria and Elliot Wamboka Mghenyi

Effect of Lengthening the School Day on Mother’s Labor Supply -Dante Contreras and Paulina Sepúlveda

Can Agricultural Interventions Improve Child Nutrition? Evidence from Tanzania - Anna Folke Larsen and Helene Bie Lilleør

The Impact of Positive and Negative Income Changes on the Height and Weight of Young Children - Thomas Buser, Hessel Oosterbeek, Erik Plug, Juan Ponce, and José Rosero

The Effect of a Transfer Program for the Elderly in Mexico City on Co-Residing Children’s School Enrollment - Emilio Gutierrez, Laura Juarez, and Adrian Rubli

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Price Information, Inter-Village Networks, and “Bargaining Spillovers”: Experimental Evidence from Ghana

“Price Information, Inter-Village Networks, and 'Bargaining Spillovers': Experimental Evidence from Ghana,” with Hildebrandt, N., Romagnoli, G., and Soldani, E., (2020).

Through a randomized experiment and detailed data on communications among farmers, we identify the impact of text-messages-based commodity price information on rural farmers’ revenues. The intervention affected prices received by farmers in two ways: (1) a long-lasting increase (9%) for treated farmers, and (2) substantial indirect benefits for certain control group farmers, which cannot be explained by classical informational spillovers. We discuss a novel mechanism of bargaining spillovers which can explain such positive externalities, even in the absence of information sharing between the treatment and control groups. Our results highlight the importance of accounting for longer-run spillovers and the potential of ICT interventions in emerging markets.

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Wages of Chagrin

Wages of chagrin. (2016, April 07). The Economist. Retrieved from https://www.economist.com/finance-and-economics/2016/04/07/wages-of-chagrin

This article from The Economist discusses:

Naidu, S., Nyarko, Y., & Wang, S. Y. (2016). Monopsony Power in Migrant Labor Markets: Evidence from the United Arab Emirates. Journal of Political Economy, 124(6), 1735-1792.

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Africa Tourism Monitor

Nyarko, Y. (edited by). (2013, 2014, 2015, 2016, 2018). Africa Tourism Monitor. Published by the African Development Bank.

The African Development Bank Group (AfDB) is delighted to present the 5th edition of Africa Tourism Monitor, which highlights travel and tourism as one of the fastest-growing and most interconnected sectors in the global economy.

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The State of Tourism in Africa

Nyarko, Y. (co-producer). (2011). The State of Tourism in Africa. Joint with the World Bank and the Africa Travel Association.

This second issue of The State of Tourism in Africa continues to tell the story of how tourism not only drives economic growth and development, but also contributes to economic recovery.

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Satellite Image Analytics, Land Change and Food Security

Chakraborty, S., Jabbar, Z., Subramanian, L., and Nyarko, Y., (2016). Satellite Image Analytics, Land Change and Food Security. ACM SIGKDD Workshop on Data Science for Food, Energy and Water (DSFEW), Co-located with KDD 2016, San Francisco, USA.

In this paper, we present the design of a satellite image analytics engine that we use to perform a detailed analysis of changes in agricultural land patterns over a 13-year time period (2000-2012) in West Bengal, India, traditionally considered one of the most fertile areas in the world.

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GreenApps: A Platform for Cellular Edge Applications

Ahmad, T., Reed-Sanchez, E., Zarinni, F., Afutu, A., Adjaho, K., Nyarko, Y., & Subramanian, L. (2018, June). GreenApps: A Platform For Cellular Edge Applications. In Proceedings of the 1st ACM SIGCAS Conference on Computing and Sustainable Societies, (p. 45). ACM.

This paper presents the design, implementation and deployment of GreenApps, a ground-up platform that enables off-grid, near off-line and highly available cellular applications in rural contexts. The GreenApps platform has been deployed in two rural regions in Kumawu, Ghana and Pearl Lagoon, Nicaragua and supports different community-centric applications.

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Computing the Rate of Disappearance of Cropland Using Satellite Images

Chakraborty, S., Dalton, S., Nyarko, Y., and Subramanian, L., (2012). Computing the Rate of Disappearance of Cropland Using Satellite Images. In Proceedings of the 3rd International Conference on Computational Sustainability, Denmark.

Apart from human-led development, changing climate is also leading towards a change in the land pattern. In both scenarios, a solution to the problem can be a monitoring tool, which can identify the change in land pattern over the years. In this paper, we present a tool that can monitor this change through satellite images.

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Managed Labor Migration in Afghanistan: A Brief Review of the Academic Migration Literature

Chartouni, C., & Nyarko, Y. (2018). Managed Labor Migration in Afghanistan: A Brief Review of the Academic Migration Literature. Washington, DC: World Bank. 

This paper presents key findings on the international experience with migration, focusing on the implications for a developing nation that is a country of origin. The paper identifies several areas of impacts: (1) increases in wages of individual migrants; (2) remittances; (3) impacts on skills and skill formation – those leaving acquire skills to enhance ability to migrate, and those returning often do so with acquired skills and work experience. 

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Preparing for Ebola Virus Disease in West African Countries Not Yet Affected: Perspectives from Ghanaian Health Professionals

Nyarko, Y., Goldfrank, L., Ogedegbe, G., Soghoian, S., & Aikins, A. D. G. (2015). Preparing for Ebola Virus Disease in West African Countries Not Yet Affected: Perspectives from Ghanaian Health Professionals. Globalization and Health, 11(1), 7.

The current Ebola Virus Disease (EVD) epidemic has ravaged the social fabric of three West African countries and affected people worldwide.

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Mobility, Human Capital, Remittances, and Economic Transformation

Nyarko, Y. “Mobility, Human Capital, Remittances, and Economic Transformation.” The Oxford Handbook of Africa and Economics: Volume 2: Policies and Practices., edited by Justin Lin et al., Oxford University Press, 480-493, 2015.

Migration and its related remittances is now an important feature of many economies, both the source countries and many destination countries.

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Actors of Change in Africa: Human Capital and Markets

Nyarko, Y. “Actors of Change in Africa: Human Capital and Markets.” Africa at a Fork in the Road: Taking Off or Disappointment Once Again?, edited by Ernesto Zedillo et al., Yale Center for the Study of Globalization, 355–363, 2015.

In this paper I will be presenting two ideas that I think are critical to economic development. The two ideas are markets and human capital.

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The Economic Development Benefits of Human Mobility to Source Countries

Nyarko, Y. (2013). The Economic Development Benefits of Human Mobility to Source Countries. Labor Mobility, an Enabler for Sustainable Development. Emirates Center for Strategic Studies and Research (ECSSR) Conference, 49-67.

Labor mobility is particularly significant in the case of the GCC; the region is host to around 15 million expatriate workers who generate US $80 billion in annual remittances each year and support and estimate 150 million dependents in their various home countries.

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Experiences in Designing a Mobile GIS Mapping Tool for Rural Farmers in Ghana

Chakraborty, S., Tong, T., Chen, J., Aman, A., Mufti, T., Nyarko, Y., & Subramanian, L. (2013). Experiences in Designing a Mobile GIS Mapping Tool for Rural Farmers in Ghana. Proceedings of the 4th Annual Symposium on Computing for Development, ACM, p. 28.

The task of balancing problems associated with population growth and food production has often been impaired by a lack of accurate information on food supply availability in any given region or time.

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The Brain Drain in Africa

Nyarko, Y. “The Brain Drain in Africa.” Oxford Companion to Economics in Africa, edited by Ernesto Aryeetey et al., Oxford University Press, 2012.

Increased attention has recently been paid to the phenomenon of the brain drain of skilled (and often unskilled) Africans from their home countries to countries in the West. In part this is because of the relatively large percentages of skilled Africans going abroad…

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The Returns to the Brain Drain and Brain Circulation in Sub-Saharan Africa: Some computations using data from Ghana

Nyarko, Y. (2011). The Returns to the Brain Drain and Brain Circulation in Sub-Saharan Africa: Some computations using data from Ghana (No. w16813). National Bureau of Economic Research.

We look at the decision of the government or “central planner” in the allocation of scarce governmental resources for tertiary education, as well as that for the individual. We provide estimates of the net present values, or cost and benefits.

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Social Safety Nets: The Role of Education, Remittances and Migration

Nyarko, Y., & Gyimah-Brempong, K. (2011). Social Safety Nets: The Role of Education, Remittances and Migration. European Report on Development.

We study the role of education as a social protection mechanism. We compare the effectiveness of direct cash handouts in comparison to education over the long-term in reducing the vulnerability to poverty.

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Review of African Household Survey Data on Social Safety-Nets and the Role of Education, Remittances and Migration

Nyarko, Y., Gyimah-Brempong, K., & Peter-Hellwig, K. (2010). Review of African Household Survey Data on Social Safety-Nets and the Role of Education, Remittances and Migration. European Report on Development.

The question of the social protection of the poor and social safety-nets in Africa has recently received attention from the European Union, United Nations agencies, as well as in many academic papers and conferences.

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The United Arab Emirates: Some Lessons in Economic Development, Working Paper

Nyarko, Y. (2010). The United Arab Emirates: Some Lessons in Economic Development, Working Paper (No. 2010/11). World Institute for Development Economics Research. Republished in Achieving Development Success: Strategies and Lessons from the Developing World, edited by Augustin K. Fosu, Oxford University Press, 2013.

Oil was discovered in the United Arab Emirates (UAE) just 50 years ago. During that time, UAE has ben able to transform itself into a rapidly modernizing country, which is fast becoming a major economic hub and a key player on the international economic landscape.

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EU Policies and African Human Capital Development

Nyarko, Y. (2010). EU Policies and African Human Capital Development. European Report on Development.

Brain Circulation between the European Union (EU) and Sub-Saharan Africa is a crucial ingredient in Human Capitol formation in the latter. A major constraint to African development is the very low base of skilled and highly educated workers and professionals.

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Is the Brain Drain Good for Africa?

Nyarko, Y., & Easterly, W. “Is the Brain Drain Good for Africa?” Skilled Immigration Today: Prospects, Problems, and Policies., edited by Bhagwati et al., Oxford University Press, 2009.

We build upon recent literature to do several exercises to assess benefits and costs of the brain drain to Africa. Contrary to a lot of the worries expressed in the media and in aid agencies, the brain drain is probably a net benefit to the source countries…

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The New Growth Theory

Nyarko, Y. “The New Growth Theory.” Fundamental Economics- Volume I (EOLSS), edited by Majumdar et al., UNESCO, 2002.

This paper very briefly summarizes some of the new growth theory in economics. The emphasis will be on the role of knowledge in the growth process.

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Comparing Learning Models with Ideal Micro & Experimental Data Sets

Nyarko, Y., & Schotter, A. (2000). Comparing Learning Models with Ideal Micro & Experimental Data Sets. New York University.

This paper compares three learning models. The models compared are the Reinforcement Learning Model of Erev and Roth, the EWA model of Camerer and Ho and a Belief Learning model in which beliefs are elicited from subjects using a proper scoring rule…

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Learning, Quantal Response Equilibrium and Equilibrium in Beliefs

Nyarko, Y. (1998). Learning, Quantal Response Equilibrium and Equilibrium in Beliefs, Working Paper (No. 01-03, revised 2001). C.V. Starr Center for Applied Economics, New York University.

This paper makes two points. First, the modeling used in the rational (Bayesian) learning literature can be generalized to handle the repeated shocks to preferences inherent and implicit in models of quantal response equilibria (QRE).

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Bayesian Learning and Convergence to Nash Equilibria without Common Priors

Nyarko, Y. (1998). Bayesian Learning and Convergence to Nash Equilibria without Common Priors. Economic Theory, 11(3), 643-655.

Consider an infinitely repeated game where each player is characterized by a ‘type’ which may be unknown to the other plays in the game. Suppose further that each player’s belief about others is independent of that player’s type…

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Convergence in Economic Models with Bayesian Hierarchies of Beliefs

Nyarko, Y. (1997). Convergence in Economic Models with Bayesian Hierarchies of Beliefs. Journal of Economic Theory, 74(2), 266-296.

I study a model where hierarchies of beliefs (the beliefs about the beliefs of other agents, etc.) are important. I provide conditions under which optimal actions of agents will converge to the Nash equilibrium of the model characterized by the true, previously unknown ``fundamentals.''

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Stepping-stone mobility

Jovanovic, B., & Nyarko, Y. (1997). Stepping-stone mobility. Carnegie-Rochester Conference Series on Public Policy, 46, 289-325.

People at the top of an occupational ladder earn more partly because they have spent time on lower rungs, where they have learned something. But what precisely do they learn?

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Optimal Growth with Unobservable Resources and Learning

Nyarko, Y., & Olson, L. J. (1996). Optimal Growth with Unobservable Resources and Learning. Journal of Economic Behavior & Organization, 29(3), 465-491.

This paper examines the problem of choosing optimal resource consumption from an imperfectly observable aggregate capital, wealth, or resource stock with the decision-maker learns about over time.

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The Bayesian Foundations of Learning by Doing

Jovanovic, B., & Nyarko, Y. (1996). The Bayesian Foundations of Learning by Doing. Econometrica, 64(6), 1299-1310.

This paper explores a one-agent Bayesian model of learning by doing and technological choice. To produce output, the agent can choose among various technologies…

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Research and Productivity

Jovanovic, B., & Nyarko, Y. “Research and Productivity.” Creation and Transfer of Knowledge, edited by Navaretti et al., Springer, Berlin, Heidelberg, 1995.

We model research as a signal on an unknown parameter of a technology. We distinguish applied from basic research and show that firms in the same industry can optimally choose different research portfolios, and that basic research van seem to have a higher rate of return than applied research, even though it really doesn’t - essentially, firms on a “fast track” upgrading policy opt for basic research but fast and slow-track upgrading policies can coexist in a long-run equilibrium.

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A Bayesian Learning Model Fitted to a Variety of Empirical Learning Curves

Jovanovic, B., & Nyarko, Y. (1995). A Bayesian Learning Model Fitted to a Variety of Empirical Learning Curves. Brookings Papers on Economic Activity. Microeconomics, (1), 247-305.

Where does technological progress come from and what determines its rate of advance? In answering these questions, it is useful to decompose technological progress into the invention of new techniques and products and the improvement of existing ones.

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Savage-Bayesian Models of Economics

Kiefer, N., & Nyarko, Y. “Savage-Bayesian Models of Economics.” Essays in learning and rationality in economics and games, Basil Blackwell, 40-62, 1995.

The “state of the art” in learning models in economics is highly unsettled. On the one hand, we have the optimizing models in which learning occurs as a byproduct…

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The Transfer of Human Capital

Jovanovic, B., & Nyarko, Y. (1995). The Transfer of Human Capital. Journal of Economic Dynamics and Control, 19(5-7), 1033-1064.

Most of our productive knowledge was handed down to us by previous generations. The transfer of knowledge from the old to the young is therefore a cornerstone of productivity growth.

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Bounded Rationality and Learning

Nyarko, Y., Woodford, M., & Yannelis, N. C. (1994). Bounded Rationality and Learning. Economic Theory, 4(6), 811-820.

Many have objected to the use of the Nash equilibrium (or more generally, Bayesian Nash equilibrium) concept in game theory, and similarly to the use of the rational expectations concept in the theory of competitive markets…

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On the Convergence of Bayesian Posterior Processes in Linear Economic Models: Counting Equations and Unknowns

Nyarko, Y. (1991). On the Convergence of Bayesian Posterior Processes in Linear Economic Models, Counting Equations and Unknowns. Journal of Economic Dynamics and Control, 15(4), 687-713.

I propose a technique, counting ‘equations’ and ‘unknowns’, for determining when the posterior distributions of the parameters of a linear regression process converge to their true values.

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Stochastic Dynamic Models with Stock-Dependent Rewards

Nyarko, Y., & Olson, L. J. (1991). Stochastic Dynamic Models with Stock-Dependent Rewards. Journal of Economic Theory, 55(1), 161-168.

We examine the behavior of optimal consumption and investment policies in aggregate stochastic growth models when utility depends on both consumption and the stock level…

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Learning in Mis-Specified Models and the Possibility of Cycles

Nyarko, Y. (1991). Learning in Mis-Specified Models and the Possibility of Cycles. Journal of Economic Theory, 55(2), 416-427.

I study the problem of a monopolist maximizing a sum of discounted profits facing a linear demand curve whose slope and intercept are unknown. I show that if the monopolist has a mis-specified model…

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On the Existence of Optimal Processes in Non-Stationary Environments

Mitra, T., & Nyarko, Y. (1991). On the Existence of Optimal Processes in Non-Stationary Environments. Journal of Economics, 53(3), 245-270.

We consider an aggregative model of intertemporal allocation under uncertainty, in which the utility and production functions are allowed to be time dependent, the random shocks occurring in each period are entirely arbitrary…

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Dynamic Optimization under Uncertainty: Non-Convex Feasible Set

Majumdar, M., Mitra, T., & Nyarko, Y. “Dynamic Optimization under Uncertainty: Non-Convex Feasible Set.” Joan Robinson and Modern Economic Theory, edited by George Feiwel, Macmillan Press, 545-590, 1989.

The object of the book is refinement, not reconstruction; it is study in ‘pure theory.’ The motive back of its presentation is twofold…

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Optimal Bayesian Control of a Nonlinear Regression Process with Unknown Parameters

Kiefer, N., & Nyarko, Y. “Optimal Bayesian Control of a Nonlinear Regression Process with Unknown Parameters.” Modeling and Control of Systems, Lecture Notes in Control and Information Sciences, edited by Austin Blaquiére, Springer, Berlin, Heidelberg, 355-362, 1989.

Economic Agents operating in uncertain, stochastic environments can face a tradeoff between current period expected reward and accumulation of information of uncertain value.

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Optimal Control of an Unknown Linear Process with Learning

Kiefer, N., & Nyarko, Y. (1989). Optimal Control of an Unknown Linear Process with Learning. International Economic Review, 30(3), 571-586.

Optimal control of a linear process with unknown parameters is considered when the horizon is infinite and rewards are discounted. Active learning strategies are considered…

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On Characterizing Optimality of Stochastic Competitive Processes

Nyarko, Y. (1988). On Characterizing Optimality of Stochastic Competitive Processes. Journal of Economic Theory, 45(2), 316-329. Reprinted in Decentralization in Infinite Horizon Economies, edited by Mukul Majumdar, Westview Press, 100-113, 1992.

A condition is provided to replace the transversality condition in characterizing the optimality of competitive processes…

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Control of a Linear Regression Process with Unknown Parameters

Kiefer, N., & Nyarko, Y. “Control of a Linear Regression Process with Unknown Parameters.” Dynamic Econometric Modelling, edited by Barnett et al., Cambridge University Press, 105-120, 1988.

Applications of forms of control theory to economic policy making have been studied by Theil (1958), Chow (1975, 1981), and Prescott (1972). Many of the applications are approximations to the optimal policy…

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