We survey recent results on the mathematical stability of Bitcoin protocol. Profitability and probability of a double spend are estimated in closed form with classical special functions. The stability of Bitcoin mining rules is analyzed and several theorems are proved using martingale and combinatorics techniques. In particular, the empirical observation of the stability of the Bitcoin protocol is proved. This survey article on the mathematics of Bitcoin is published by the Newsletter of the European Mathematical Society, vol.115, 2020, p.31-37. Continuation of arXiv:1601.05254 (EMS Newsletter, 100, 2016 p.32).
An open distributed system can be secured by requiring participants to present proof of work and rewarding them for participation. The Bitcoin digital currency introduced this mechanism, which is adopted by almost all contemporary digital currencies and related services. A natural process leads participants of such systems to form pools, where members aggregate their power and share the rewards. Experience with Bitcoin shows that the largest pools are often open, allowing anyone to join. It has long been known that a member can sabotage an open pool by seemingly joining it but never sharing its proofs of work. The pool shares its revenue with the attacker, and so each of its participants earns less. We define and analyze a game where pools use some of their participants to infiltrate other pools and perform such an attack. With any number of pools, no-pool-attacks is not a Nash equilibrium. We study the special cases where either two pools or any number of identical pools play the game and the rest of the participants are uninvolved. In both of these cases there exists an equilibrium that constitutes a âtragedy of the commonsâ where the participating pools attack one another and earn less than they would have if none had attacked. For two pools, the decision whether or not to attack is the minerâs dilemma, an instance of the iterative prisonerâs dilemma. The game is played daily by the active Bitcoin pools, which apparently choose not to attack. If this balance breaks, the revenue of open pools might diminish, making them unattractive to participants.
The main subject of this thesis is a paradigm of instability and stabilization in coalition forming among countries as rational actors, presented through a Statistical Physics inspired model.This is an interdisciplinary work involving the fields of applied mathematics and sociophysics, as well as the political applications in the real cases from past and present. Applied to political,economic and social problems, the models can be used to analyze a wide variety of real cases -- international alliances, economic or business alliances, coalitions of political parties, socialnetworks, and organizational structures.In the first part of this thesis we present and analyze the coalition forming and the instability among rational actors coupled with pairwise static historical propensity bonds that have evolvedindependently. Such organization leads to discordant associations into coalitions and the instability as a consequence of decentralized maximization of the individual benefits gained fromjoining or leaving the coalitions. We define Natural Model of coalition forming and address the questions of instability and stabilization among actors possessing different levels of rationality. The framework presented here allows to analytically calculate the optimal and non-optimal stable configurations of actors' coalitions. We then investigate the coalition forming and the stabilization under the influence of externally-set opposing global alliances, which are represented in Global Alliance Model. The stabilization is produced through new cooperations based on the effect of polarization of several distinct interests shared by actors, which generates interest-based propensities and enables a planned coalition forming. We then investigate the effect of dissolution of a global alliancewhich, together with the competing alliance, has previously generated stable coalitions.A special section of the thesis is devoted to investigation and illustration of coalition forming in real historical cases. This part presents the analysis of unstable coalitions in Europe - cycling in the England-Spain-France conflicting triangle and creation of the Italian state, as well as of the remarkable historical cases of the Soviet global alliance collapse, of the recent internal conflict in Syria, and of the "paradoxical stability" in the Eurozone.In the second part of this thesis, we present a simulation of the coalition forming models. The simulation allows to follow graphically the coalition forming processes. We present the methodology used in the simulation, as well as its application in the illustration of coalition forming in the prototypes of real case systems. Given exact propensity values, which is fairly consideredto be the most difficult part of coalition forming modeling, the simulation tool can be used to predict optimal and non-optimal spontaneous stabilizations and globally motivated stabilities inreal cases.An independent part of the thesis is devoted to the subject of viability correction in dynamic network of actors. The model is a finite set of autonomous actors with states that evolveindependently and connected into a network via their connection operators, which evolve independently as well. The network is defined to be viable if a joint evolution satisfies the centralized scarcity constraints set by the environment. In order to restore the viability of these decentralized dynamics, we apply to the method of correction by viability multipliers used in Viability Theory, where the multipliers play the role of decentralizing prices. Standing apart from the main course of the thesis, the subject of viability correction in dynamic network of actors suggests an interesting theoretic dynamical generalization of coalition stabilization in our models inspired from Statistical Physics.
The minmax regret problem for combinatorial optimization under uncertainty\ncan be viewed as a zero-sum game played between an optimizing player and an\nadversary, where the optimizing player selects a solution and the adversary\nselects costs with the intention of maximizing the regret of the player. The\nexisting minmax regret model considers only deterministic solutions/strategies,\nand minmax regret versions of most polynomial solvable problems are NP-hard. In\nthis paper, we consider a randomized model where the optimizing player selects\na probability distribution (corresponding to a mixed strategy) over solutions\nand the adversary selects costs with knowledge of the player's distribution,\nbut not its realization. We show that under this randomized model, the minmax\nregret version of any polynomial solvable combinatorial problem becomes\npolynomial solvable. This holds true for both the interval and discrete\nscenario representations of uncertainty. Using the randomized model, we show\nnew proofs of existing approximation algorithms for the deterministic model\nbased on primal-dual approaches. Finally, we prove that minmax regret problems\nare NP-hard under general convex uncertainty.\n
We analyze how network effects affect competition in the nascent cryptocurrency market. We do so by examining the changes over time in exchange rate data among cryptocurrencies. Specifically, we look at two aspects: (1) competition among different currencies, and (2) competition among exchanges where those currencies are traded. Our data suggest that the winner-take-all effect is dominant early in the market. During this period, when Bitcoin becomes more valuable against the U.S. dollar, it also becomes more valuable against other cryptocurrencies. This trend is reversed in the later period. The data in the later period are consistent with the use of cryptocurrencies as financial assets (popularized by Bitcoin), and not consistent with "winner-take-all" dynamics.
Marcelo Arenas, Juan L. Reutter, Etienne Toussaint, MartĂn Ugarte ¡ 6 authors
In the consensus protocols used in most cryptocurrencies, participants called miners must find valid blocks of transactions and append them to a shared tree-like data structure. Ideally, the rules of the protocol should ensure that miners maximize their gains if they follow a default strategy, which consists on appending blocks only to the longest branch of the tree, called the blockchain. Our goal is to understand under which circumstances are miners encouraged to follow the default strategy. Unfortunately, most of the existing models work with simplified payoff functions, without considering the possibility that rewards decrease over time because of the game rules (like in Bitcoin), nor integrating the fact that a miner naturally prefers to be paid earlier than later (the economic concept of discount). In order to integrate these factors, we consider a more general model where issues such as economic discount and decreasing rewards can be set as parameters of an infinite stochastic game. In this model, we study the limit situation in which a miner does not receive a full reward for a block if it stops being in the blockchain. We show that if rewards are not decreasing, then miners do not have incentives to create new branches, no matter how high their computational power is. On the other hand, when working with decreasing rewards similar to those in Bitcoin, we show that miners have an incentive to create such branches. Nevertheless, this incentive only occurs when a miner controls a proportion of the computational power which is close to half of the computational power of the entire network.
Due to the explosive development of global network structure, electronic commerce is increasingly playing an important role in many organizations and individual consumerâs daily life. It offers opportunities to significantly improve the way for businesses interactions between both customers and suppliers. More and more large scale and decentralized ecommerce mechanisms have emerged in industrial and commercial domains in a wide range. In particular, among all these applications, online auctions, which are flexible pricing mechanisms over internet, make the physical limitations of traditional auctions disappear. They gain their extra popularity in the daily life and attract globally dispersed users due to having the characteristics that âbargainingâ and ânegotiationâ besides all of the convenience. Thus, online auctions become one of the most widely studied and employed negotiation mechanisms today. Traditionally, in most current online auction applications, the traders are generally humans who operate all the behaviors to make transactions. These behaviors may involve observing the auctions, analyzing the auction information, and bidding the suitable price for the items. However, facing the increasingly demanding requirements and complexity of online trading, this kind of manual operation does not reveal the full potential of this new mode of commerce. Thus, in order to relieve the users and be more effective, exploring possible types and automating the behaviors in the online auction attract high interest. Now, in many studies, the agent-oriented auction mechanism, with its emphasis on autonomous actions and flexible interactions, arises as an effective and robust model for the dynamic and sensitive commerce environment. In such systems, the agent acts flexibly on behalf of its owner and is capable of local decision-making based on the environment information and pre-knowledge about the system. Among many different types of online auction, two of the most popular and studied types are Multiple Round English Auctions (MREA), which is single side auction, and Continuous Double Auction (CDA), which is double side auction. These auctions are newly emerged in e-commerce era based on the traditional auction types. They allow multiple agents to participate and one agent can deal with several auctions continuously or simultaneously, which are effective auction types to save time and relieve the users. Towards to these types, because there is no centralized system-wide control, the major challenge for automatic bidding strategies is to improve the degree of automation and optimize the agentâs bidding behavior in order to maximize the ownerâs profit. Most of the related researches have been conducted by using heuristic methods and fixed mathematical functions to compute the final optimal bidding price for the items or to compute how much should bid at each time step. Nevertheless, because auction environments are complicated and highly dynamic due to have many factors affecting each other, these approaches are not flexible enough for the dynamic environment, and there is no dominant strategy. Against this background, this thesis is concerned with developing the intelligence of autonomous agentâs bidding strategy in order to make the agent to be more efficient and competitive for agent-based online auction mechanisms, especially in MREA and CDA. In order to be more flexible and better exploit the market information, Genetic Network Programming (GNP) is firstly employed to the agentâs bidding strategy since its applicability and efficiency have been clarified in complex and dynamic problems in many other fields. GNP is one of the evolutionary optimization techniques developed as an extension of Genetic Algorithm (GA) and Genetic Programming (GP), which uses compact directed graph structures as solutions. Basically speaking, in the proposed method, the GNP population represents the group of potential bidding strategies, and each individual uses the as-if/then decision-making functions to judge the auction information and guides the agent to take the suitable actions under different situations. Thus, it could be flexible and capable to adaptive to various auction situations. During the evolution, the GNP structure will be systematically organized, and finally, the individual which can obtain the highest profit is selected as the optimal bidding strategy at the end of training phase. In chapter 2, we introduced the conception of MREA and CDA in detail, which are the study environments in this thesis. The related researches are also introduced. In chapter 3, focusing on MREA, the bidding strategy for the auction agents in MREA is proposed using GNP. The performance of GNP-based agents is evaluated and studied in two situations: MREA is no time limit (NTL), and MREA is time limit (TL). Furthermore, according to the amount of the money each agent has, each situation is divided into 2 cases: general case and poorest case. All the participating agents in the simulations use GNP strategy. This chapter aims to study and analyze the capability and effectiveness of GNP for guiding bidding actions through the phenomenon of the simulations. The simulation results reveal that the agents using GNP strategy can understand various environments well through experiences and become smarter through evolution. In chapter 4, as an extension of the bidding strategy in chapter 3, in order to improving the agentâs intelligence and sensitivity, an enhanced bidding strategy for MREA is developed using GNP. Firstly, the GNP structure is modified to be able to judge more kinds of information and more situations at a time. Secondly, the strategy is improved to be able to consider the bidderâs attitude towards to each good, which makes the strategy to be more personalized for each bidder and could make the bidder more satisfied with the auction result and profit. The proposed strategy is compared with the previous GNP strategy and the other conventional strategies in the simulations. The simulation results demonstrated that the proposed method can outperform the previous one and is more competitive than the agents based on mathematical functions. In chapter 5, focusing on CDA, GNP with rectify nodes (GNP-RN) has been applied for CDA bidding strategy combined with proposed heuristic rules, which are derived based on the common believes for assisting agentâs bidding behavior. GNP-RN is developed aiming to guide the agent to be competitive under different CDA environments, and maximize the agentâs profit without losing chances for trading. Rectify Node (RN) is a newly proposed kind of nodes, which is used for bringing more flexible and various options for bidding action choices. 4 groups of simulations are designed to compare GNP-RN with conventional GNP and other strategies in CDA. In each simulation, the kinds of opponent agents are different in order to fully analyze the agentsâ performance. The simulation results show that the proposed method can outperform all the other strategies and achieve high success rate as well as high profit even when the situation is highly competitive. In chapter 6, as an extension of GNP-RN, GNP with adjusting parameters (GNP-AP) for developing bidding strategy in large-scale CDAs is proposed and studied. In large-scale CDAs, much more history information can be obtained than small-scale CDAs. In order to enhance the sensitivity for large-scale CDAs and the capability of judging abundant information, the parameters used by GNP-AP decision-making functions are adjusted during the evolution instead of being fixed in GNP-RN. Moreover, the structure of GNP-AP is designed to be more comprehensive that the number of branches of some kinds of nodes is increased to adapt to the complicated environment situations. The simulation results show that GNP-AP can obtain a good guidance for the large-scale CDAs and could be very efficient for the markets. In chapter 7, after giving the objectives and motivation of each research in this thesis, some conclusions about the proposed algorithms are described based on the simulation results.
Abstract. We study the probability that two or more agents can attain common knowledge of nontrivial events when the size of the state space grows large. We adopt the standard epistemic model where the knowledge of an agent is represented by a partition of the state space. Each agent is endowed with a partition generated by a random scheme consistent with his cognitive capacity. Assuming that agents â partitions are independently distributed, we prove that the asymptotic probability of nontrivial common knowledge undergoes a phase transition. Regardless of the number of agents, when their cognitive capacity is sufficiently large, the probability goes to one; and when it is small, it goes to zero. Our proofs rely on a graph-theoretic characterization of common knowledge that has independent interest.
We study repeated games in which players have imperfect execution skill and one playerâs true skill is not common knowledge. In these settings the possibility arises of a player âhustlingâ, or pretending to have lower execution skill than they actually have. Focusing on repeated zero-sum games, we provide a hustle-proof strategy; this strategy maximizes a playerâs payoff, regardless of the true skill level of the other player. 1
Shlomi Dolev, Panagiota N. Panagopoulou, MikaÍl Rabie, Elad M. Schiller ¡ 5 authors
Players in a game are assumed to be totally rational and absolutely smart. However, in reality all players may act in non-rational ways and may fail to understand and find their best actions. In particular, participants in social interactions, such as lotteries and auctions, cannot be expected to always find by themselves the "best-reply" to any situation. Indeed, agents may consult with others about the possible outcome of their actions. It is then up to the counselee to assure the rationality of the consultant's advice. We present a distributed computer system infrastructure, named rationality authority, that allows safe consultation among (possibly biased) parties. The parties' advices are adapted only after verifying their feasibility and optimality by standard formal proof checkers. The rationality authority design considers computational constraints, as well as privacy and security issues, such as verification methods that do not reveal private preferences. Some of the techniques resembles zero-knowledge proofs. A non-cooperative game is presented by the game inventor along with its (possibly intractable) equilibrium. The game inventor advises playing by this equilibrium and offers a checkable proof for the equilibrium feasibility and optimality. Standard verification procedures, provided by trusted (according to their reputation) verification procedures, are used to verify the proof. Thus, the proposed rationality authority infrastructure facilitates the applications of game theory in several important real-life scenarios by the use of computing systems.
Ali Kakhbod, Joseph C. Koo, Demosthenis Teneketzis
We present a decentralized message exchange process (tatonnement process) for determining the level at which a certain public good will be provided to a set of individuals who finance the cost of attaining that level. The message exchange process we propose requires minimal coordination overhead and converges to the optimal solution of the corresponding centralized problem.
Epidemic theory has wide range of applications in computer networks, from spreading of malware to the information dissemination algorithms. Our society depends more strongly than ever on such computer networks. Many of these networks rely to a large extent on decentralization and self-organization. While decentralization removes obvious vulnerabilities related to single points of failure, it leads to a higher complexity of the system. A more complex type of vulnerability appears in such systems. For instance, computer viruses are imminent threats to all computer networks. We intend to study the interaction between malware spreading and strategies that are designed to cope with them. The main goals of this thesis are: 1. to analyze influence of network topology on infection spread 2. to determine how topology can be used for network protection 3. to formulate and study optimization of malware protection problem with respect to topology 4. to investigate non-cooperative game of security We used analytical tools from various fields to answer these questions. First of all, we have developed homogeneous and heterogeneous N-intertwined, susceptible - infected - susceptible (SIS) model for virus spread. This model is used to determine the influence of topology on the spreading process. For the N-intertwined model, we show that the largest eigenvalue of the adjacency matrix of the graph rigorously defines the epidemic threshold. The results of the model also predict the upper and lower bounds on epidemics as a function of nodal degree. The epidemic threshold is found to be a consequence of the mean field approximation. However, slow convergence to the steady-state justifies the application of the threshold concept. We used the exact 2N-state Markov chain model to explore the phase transition phenomenon for two contrasting cases, namely the line graph and the complete graph. The N-intertwined model assumes that the infection spreading over a link is a Poisson process. By introducing infection delay, we studied the influence of deviation from Poisson process assumption on epidemic threshold for the special case of a complete bi-partite graph. Due to the special structure of bi-partite graphs we were also able to derive approximate formula for the extinction probability in the first phase of the infection. In the case of SIS epidemic models, the effects of infection depend on the protection of individual nodes. We studied optimization of protection scheme for different networks. We use the results from heterogeneous N-intertwined model to determine the global optimum at the threshold. Above the threshold, the problem is a sum of ratios fractional programming problem, which is NP-complete. Therefore, we only determine the upper bound on the optimum. Contrary to the common sense, reducing the probability of infection for higher degree nodes pushes the network out of the global optimum. For the case of complete bi-partite graphs, we derive optimal threshold if only 2 fixed protection rates are available. Computer networks are generally distributed systems and protection cannot be globally optimized. The Internet is an extreme example: there is no global control center, and obtaining complete information on its global state is an illusion. To approach the issue of security over decentralized network, we derived a novel framework for network security under the presence of autonomous decision makers. The problem under the consideration is the N players non-cooperative game. We have established the existence of a Nash equilibrium point (NEP). The willingness of nodes to invest in protection depends on the price of protection. We showed that, when the price of protection is relatively high for all the nodes, the only equilibrium point is that of a completely unprotected network; while if this price is sufficiently low for a single node, it will always invest in protecting itself. We determine bounds on the Price of Anarchy (PoA), that describes how far the NEP is from the global optimum. We have also proposed two methods for steering the network equilibrium, namely by influencing the relative prices and by imposing an upper bound on infection probabilities. A quarantine is another possible measure against the epidemic. A quarantine on a set of network nodes separates them from the rest of the network by removing links. The concept of threshold and the N-intertwined model provides a tool to analyze how quarantine improves the network protection. We studied several different networks from artificially generated to real-world examples using the modularity algorithm. The real-world networks tend to show a better epidemic threshold after clustering than artificially generated graphs. The real-world networks have typically two or three big clusters and several smaller ones, while Barabasi-Albert (BA) and Erdos-Renyi (ER) graphs have several smaller clusters comparable in size. However, the number of removed links in a graph using modularity algorithm is unjustifiably high, suggesting that complete quarantine is not a viable solution for real-world networks.
Stuart M. Allen, Gualtiero B. Colombo, Roger M. Whitaker
We address the problem of cooperation in decentralized systems, specifically looking at interactions between independent pairs of peers where mutual exchange of resources (e.g., updating or sharing content) is required. In the absence of any enforcement mechanism or protocol, there is no incentive for one party to directly reciprocate during a transaction with another. Consequently, for such decentralized systems to function, protocols for self-organization need to explicitly promote cooperation in a manner where adherence to the protocol is incentivized. In this article we introduce a new generic model to achieve this. The model is based on peers repeatedly interacting to build up and maintain a dynamic social network of others that they can trust based on similarity of cooperation. This mechanism effectively incentivizes unselfish behavior, where peers with higher levels of cooperation gain higher payoff. We examine the model's behavior and robustness in detail. This includes the effect of peers self-adapting their cooperation level in response to maximizing their payoff, representing a Nash-equilibrium of the system. The study shows that the formation of a social network based on reflexive cooperation levels can be a highly effective and robust incentive mechanism for autonomous decentralized systems.
We consider a continuous-time version of fictitious play (FP), in which interacting players evolve their strategies in reaction to their opponents' actions without knowledge of their opponents' utilities. It is known that FP need not converge, but that convergence is possible in certain special cases including zero-sum games, identical interest games, and two-player/two-move games. We provide a unified proof of convergence in all of these cases by showing that a Lyapunov function previously introduced for zero-sum games also can establish stability in the other special cases. We go on to consider a two-player game in which only one player has two-moves and use properties of planar dynamical systems to establish convergence.
We consider the problem of dynamic pricing in a bandwidth market, where users arrive into a network according to a known stochastic traffic model, and request resource according to their class-specific demand functions. The aim of the bandwidth owner (vendor) is to maximize its revenue. We first consider the single-vendor case and provide three different pricing schemes for this setting. Using simulation results we show that model-based schemes outperform an appropriately tuned model-free scheme. We then extend the problem formulation to a Markov game by considering two vendors in the market. We give heuristic pricing schemes for this problem that attempt to find a Nash equilibrium in a restricted policy space, and provide simulation results. We then present an opportunistic pricing scheme that exploits knowledge of the pricing scheme being used by its opponent and empirically show that this scheme indeed benefits from such knowledge. The success of this opportunistic scheme emphasizes the need for sophisticated strategies for Markov games with large state spaces. Motivated by this need, we present a key approximation theorem for zero-sum, discounted Markov games, and use it to prove statespace-sizeâindependent performance bounds on two sampling techniques. Specifically, we extend the policy-rollout technique for Markov decision processes to Markov games, and establish that under certain conditions, the policy generated by this algorithm outperforms the base policy in the sup norm. We also provide an alternate proof of near-optimality of the sparse-sampling algorithm developed by Kearns et al. We provide simulation results to empirically evaluate the new policy-rollout technique.
B. Balamurugan, T. Poongodi, M. R. Manu, S. Karthikeyan ¡ 5 authors
The moving image archive of the US Agency for International Development (USAID) includes a copy of the film The Double Day (1975), cataloged in the series Moving Images Relating to International Development Programs and Activities, 1979â1991, a collection of more than eight hundred titles âcreated to provide information on assistance programs supported by the Agency for International Development (AID).â1 Yet, The Double Day does not, in fact, directly depict or engage with any specific development or aid initiative. Instead, the filmâdirected by US-based Brazilian filmmaker Helena Solberg as part of the International Womenâs Film Project collective and described as âthe first Latin American feminist documentaryââexamines the gendered dynamics of paid and unpaid labor through the testimonies of women from Argentina, Bolivia, Venezuela, and Mexico.2 Its presence in the USAID archive is likely a consequence of its funding history, having received support from the Inter-American Foundation, a USAID-affiliated entity; the development agencies of Denmark, Norway, and Sweden; the United Nations Development Program; and US philanthropist Calvin Cafritz.3These transnational funding structures not only enabled the filmâs production but also determined its archival destination, which renders legible its place within the history of international development.4 The Double Dayâs institutional trajectory reflects the shifting configurations of aid, gender, and media during a historic moment when women were being repositioned at the center of what Arturo Escobar has described as developmentâs âregimes of visuality.â5 Especially relevant to The Double Dayâs production and exhibition was the international institutional framework of Women in Development (WID). Emerging in the early 1970s and culminating in United Nationsâ proclamation of 1975 as International Womenâs Year, WID emphasized womenâs participation in the global economy as both an index and mechanism of development. Indeed, The Double Day premiered at the World Conference of the International Womenâs Year, held in Mexico City.6 Within this context, the film forms part of a broader trajectory of media use by international organizations that intensified during the 1970sâas best exemplified by Media Habitat, a collection of 236 documentary films commissioned by the United Nations to represent urban and rural development initiatives for the 1976 Habitat Conference on Human Settlements in Vancouver. As a policy-shaping initiative, Media Habitat primarily featured films from the Global South intended not only to illustrate but also to help codify standardized audiovisual markers of âunderdevelopmentâ that determined access to the emerging global economic order and to international aid.7Framed in relation to these international institutions and their operations, The Double Day could similarly be considered âdevelopment mediaââexemplifying the type of nonfiction media produced and distributed outside of the commercial film circuits whose aspects and subcategories have been variously described in scholarship as nontheatrical, useful, sponsored, institutional, industrial, educational, or nonprofessional/amateur.8 Scholars working in this area have emphasized the institutional contexts of such mediaâs production and exhibition infrastructures as shaping its instrumentalized effects. From a feminist perspective, such an approach is crucial to grappling with the broader question of how âgender impacts [these worksâ] shape, content, and trajectories.â9 Yet we also argue that, taken in isolation, the institutional and infrastructural contexts are insufficient to account for the complex relationship between media and development, potentially not only limiting our understanding of the reach and impact of development but also distorting our interpretive conclusions. For example, to categorize The Double Day as âdevelopment mediaâ is to overlook the filmâs place within Solbergâs directorial oeuvre, as well as within the histories of both transnational womenâs filmmaking and radical Latin American documentary cinema to which it simultaneously belongs. Such exclusive framing is especially limiting given that women globally were disproportionately engaged in nonfiction production throughout the twentieth centuryâsometimes by political choice but more often due to structural exclusions from fiction filmmaking. Even in nonfiction historiography, however, institutional media has remained particularly marginal, reinforcing hierarchies that separate such works from the aesthetic and authorial frameworks through which film history has been constructed.10 This marginalization not only tends to erase womenâs contributions but also presumes a âweakâ or derivative authorship, rendering these films unworthy of the interpretive attention needed to apprehend their aesthetic and political complexity.11 The same dynamic is likely to structure assumptions about âdevelopment mediaâ as well.Categorizing The Double Day exclusively within this category would further prompt us to assume top-down institutional analyses that have been characteristic of both institutional media methodologies and the scholarship on development at large. This, in turn, would risk obscuring this filmâs radical Marxist approach to womenâs labor as well as its concrete contribution to activism and its attendant grassroot structures. In Mexico City, The Double Day became a catalyst for feminist solidarity in practice when one of the filmâs protagonists, Bolivian activist and trade unionist Domitila Barrios de Chungara, was invited to participate in the Tribune of Non-Governmental Organizations held alongside the official UN conference.12 There, Barrios de Chungara challenged Western feminist priorities by reframing the debate around labor, class, and imperialism, helping to articulate a shared Third World feminist agenda that significantly departed from the developmentalist vision of the United Nations and USAID.13 Seen through the lens of activist media, The Double Day helped forge transnational solidarity networks by enabling information exchange across the diverse voices that shaped its makingâfrom the women featured in the film to the activists who circulated itârevealing a considerably more dynamic interplay between institutional and grassroots or contingent media practices.Moreover, the filmâs Latin American contextâreflected in Solbergâs formation in Brazil as the only woman in Cinema Novo, its focus on women from across the region, and its premiere and key reception in Mexico Cityârequires grappling with the regional specificities of the very notion of development in its multiple iterations.14 Far from being an epistemological and political framework imposed solely by the Global North, both the practices of development and the theoretical foundations of developmentalism (understood as a broad and polysemic set of discourses) were shaped through the active participation of Latin American economists.15 Within this iteration, underdevelopment, as a constitutive notion of developmentalism, became central to a distinctly critical strand, which by the late 1960s became known as the dependency theory.16 This same approach is reflected in some of the best-known Latin American radical film manifestos of the time, arising precisely from the same milieus to which Solberg belonged.17These various considerations of the filmâs history illustrate the methodological challenges confronting feminist scholars seeking to assess the impact of development on media projects, theories, and practices. To disregard the developmentalist context of such works by emphasizing their political aesthetics and affects risks reproducing a romanticized narrative of heroic resistance (albeit from a feminist perspective). Yet to engage exclusively with their institutional and material infrastructures risks naturalizing developmentalismâs political and epistemological foundations at the expense of the goals and beliefs of the many women who participated in these projects. The contradictions and ambivalences that animate such histories call for feminist frameworks capable of holding both institutional complicity and radical possibility in view.This challenge resonates with ongoing debates about the politics of the archive and what Allyson Field has termed âthe practice of informed speculation.â18 As she reminds us, feminist, queer, and decolonial methodologies have long taught us to âpress at the limitsâ of the archive to âinoculate our scholarship against our evidenceâs afflictions.â19 The concern that the evidence we draw on in our analysis reproduces the very structures and blind spots of the dominant ideology and therefore shapes and delimits our interpretation becomes particularly urgent when engaging the developmentalist media corpus. Informed speculation offers an alternative by inviting the experimental, creative, and speculative rewriting of history, mobilizing the archive âin a project that runs counter to the original purpose, or the imperative to preserve, or the conditions that led to erasure.â20 Yet, as Field cautions, such speculative gestures must remain grounded in a deep and âintimate familiarity with the archiveâ that we are working with and against. Building on this imperative, we suggest that the developmentalist archive, in particular, demands expansion and critical reconsideration in ways that unsettle the very disciplinary frameworks through which it has been studied as well as the larger institutional contexts for such knowledge production.Our focus on The Double Day in the opening of this introduction thus foregrounds the entanglements of institutional and grassroots forces, local and international contexts, structural and interpersonal relations, and creative and economic factors that have shaped not only this film but the broader ecosystem of development media projectsâand their preservationâover time. Addressing such a constellation involves transgressing methodologically entrenched divisions between political economy and aesthetics, between material infrastructures and affective regimes; reckoning with divergent periodizations across film history and world economics; and situating these within the local specificities of womenâs movements and international institutional programs. It also demands attentiveness to the coexistence of multiple, and sometimes competing, understandings of developmentâeach historically, geographically, and ideologically situated.We imagine this special issue as an opening toward a critical dialogue, not only about how such an approach might be enacted in practice but also about the far-reaching ways development paradigms have shaped both our objects of study and the contours of the field itself. The decision to center institutionally sponsored films across all the essays in this issue is deliberate and enables us to highlight institutional critique as a vital methodological imperative within our analytical framework. Created within the frameworks of international organizations, state agencies, or NGOs, these filmsâ histories make legible the institutional logics that underwrite their production. Yet our critique does not stop at these specific entities. Rather, we argue for a broader interrogation of the political conditions and institutional infrastructures that shape media and knowledge production more generally. This includes contemporary corporations embedded in the digital platform economy, from streaming services to the rapid expansion of AI. Equally critical is a reflexive examination of academia itself, where departments of economics, political science, and centers for development have played a formative role in producing and legitimizing developmentalist theories and policy frameworks. While the humanities and arts have at times offered critical alternatives, they have also frequently mirrored and reinforced many of the same developmentalist assumptions. A feminist analysis of the nexus between development and media must therefore unsettle not only dominant archives but also the institutional and disciplinary foundations of our own scholarly practices.As scholars, we share the complex position of navigating the same tensions between institutional complicity and emancipatory aspiration as many of the media-makers whose work we study. Mirroring our subjects is also the transnational, collective mode of this special issueâs own production as it emerges from an ongoing informal working group we have sustained over several years. While relying on institutional and disciplinary affordancesâsuch as university funding for conferences or access to academic publishing platformsâwe have been working toward creating a community that exceeds, and often resists, the prevailing logics of our academic institutions. Our aim has been to create a space for shared inquiry and mutual support that pushes back against disciplinary siloing and technocratic neoliberal assessment modes of both labor and knowledge productionâand this certainly extends to our experience collaborating with the journal editors throughout the publication process. Our goal has been to examine both the persistence and variability of developmentalism, understood as what Gustavo Esteva calls a âpowerful but fragile semantic constellation,â as a conceptual formation that has historically inspired, legitimized, and mobilized media projects across Asia, Africa, and Latin America.21 And gendered biopolitics, from population control to gender mainstreaming, have remained integral to development policies and media practices, recurring across formats from institutional newsreels to film festivals.We share the conviction that, far beyond the history of nonfiction institutional media, development (as both a broad ideological project and a network of material and institutional practices) and developmentalism (as a set of discourses and theoretical models associated with development) have exerted a far-reaching influence on film and media cultures at large. As such, they must be treated as a major force in shaping global film and media systems and also the many ongoing assumptions behind their critical discourses. The discipline of communication studies was founded on modernization theory governed by Cold War goals of dissemination of Western liberal democracy around the world, while âan area studies framework allowed compartmentalizing Western and non-Western outcomes of technologies that were always claimed to be universal.â22 Despite critique from postcolonial and critical race studies, many of these frameworks have remained foundational for media theory.23 In historical scholarship, as we increasingly move beyond âmodernityâ as a dominant conceptual anchor, engaging with practices and discourses of development opens more precise analytical pathways. These film and mediaâs entanglements with the logics of and economic and the associated with as well as their conceptual underdevelopment, and impact in as diverse as and of media aesthetic and paradigms in film and film and funding are developmentalist assumptions to the they to underwrite the narrative and logics of and global media from the structure of the film to the cultures of argue that a examination of the historical entanglements between film and developmentalist aesthetics, modes of as well as infrastructures and critical the and that our contemporary media is a of the historical contours of development as a field of inquiry embedded within a of some of the methodologies by the featured in this special a of this complex history, to the larger at in media, development, and gender all its development a it as an of be with practices as divergent as and in In as we work on this the of the of the USAID the ideological that have the history of international the and of this on the global its a from development as a global practice and as an institutional and which over the has as a with its own media Yet or does not erase the historical impact of these the contradictions they have reflected and over the as the of development several crucial to the economic theories of development initiatives to and through the of the development an international policy framework at from the Global to the of the Global the by the political role of and the of the International the on was challenged by dependency theory and at development as global structural the neoliberal of the the Programs by the and World imposed and as conditions for and forms of assistance became known as the major markers for international development development has moving beyond economic to such as the Human Development and the Development and from international organizations such as the United Nations to a broader network of These frameworks increasingly of and liberal of and with what in many ways to various while the of the to developmentâs epistemological more scholarship has toward a of its and material the field has to a of and critical by and scholars, which development as a dynamic of conceptual and political to these the studies in this special issue call for sustained analysis in place of In we draw from a of and that in of of gender and to this special issue engage that and from Mexico to contemporary specific local historical of global distinctly feminist methodologies as well as attention to studies that this issue a in the global history of development on and documentary work in Mexico how early women infrastructures as of while US films an early of state and transnational on a outside the Global as the of developmentalist both the and markers of development media, its to the and Latin central grounded in archival also womenâs in transnational and the methodological of archives on study of the series to a a digital media not by but by women not as but as subjects and within circuits of neoliberal and the aesthetics and of how developmentâs has models of to contemporary neoliberal paradigms of and analysis how digital and gender and practices, discourses on and their of these essays the of some of the historical of developmentalist as the question of the role of the state within such on a notion of economic as a and the dominant of development that the state as the for and through infrastructural projects. This understanding of development was shared across both of the as well as in the Third The United and the increasingly mobilized international in the of the modes of international at the postcolonial of policy and ideological These programs were at the expansion of their and of while with the and decolonial of The conceptual between modernization and development that the Cold in of and hierarchies of that long and As an of postcolonial their role as of international aid concern about the of Western development projects. In alternative across the Global South that to structural between and through policies of and In many they were further the global structures. In Latin for example, this approach was through organizations such as the United Nations for Latin and the both developmentalist projects and their have taken many forms historically, and they have and they have been to a of projects, and postcolonial and development has been and in ways and with frequently political While many of these alternative frameworks the embedded in dominant Western they often technocratic and assumptions. gender and gender as for the of to be shaped by This becomes particularly in the media that of development where women frequently a crucial associated with and women were as both the subjects and of their participation in the and labor often as the index of In this study of from the 1970s how women were as of this as these about womenâs urban and recurring and of a within the own of and critique that official examination of archives and enables a feminist interrogation of their mobilizing a of the in the of contribution to this issue similarly the of a dynamic within as well as across ideological the of womenâs and the media of the and as active in labor and as integral to the technocratic women became of as their labor remained a of and analysis and archival with attention to the specific of and It also transnational that as a and affective a nexus of and practices through which gender, media, and developmentalism one film not as a but as part of the of alongside and work a broader concern of this special media as a of developmentalist projects. The debates the World and which international such as the United Nations and a critical historical for such primarily by postcolonial and of the for the of media and communication infrastructures in as to counter Western The a between and economic how systems of media and reinforced global hierarchies of and in an agenda that supported and alternative media infrastructures across postcolonial contexts, the framework gender as an analytical This âgender in the 1970s by of the Women in Development in relation to The Double its political critique of with its broader to center women in development policy through and This was also in of media, which was shaped by its international reach and audiovisual production and and and Yet, as WID institutional it also to the and of the womenâs development programs often by in These were by a of studies, and on and the to of womenâs presence and through the of their economic and In this on the filmmaker this history directly by the and of for women by the WID framework during the with and agencies the of and against Women in at the of the neoliberal turn, when institutional media often the only to access and support to projects. The an by this dynamic as of the from the Global South are to engage with the developmentalist assumptions funding models that their similarly the as a in developmentalist media history by the of and centers on the Film a between of and the attention toward the and labor by and work was foundational the of and the of audiovisual aid, as both a of development projects and a critical for their the in this issue argue for a with media, gender, and developmentalism as an field of that is and shaped by feminist and methodologies and that challenge the entanglements between academic knowledge production and and technocratic development And while methodological these dynamics at the structural the of feminist in media and cinema by this the very a