Learning competitive equilibrium in laboratory exchange economies

A laboratory market for two goods is instituted to examine the hypothesis that individuals will eventually coordinate on the induced competitive equilibrium. The mechanism for exchange strongly restricts the space of agent actions, facilitating the identification of decision rules. Evidence for learning competitive equilibrium is mixed due to strong heterogeneity in decision making. Some subjects forego immediately available gains when they expect the market to move in a more favorable direction, a condition necessary for coordinating on the competitive outcome. However, a majority do not, and many are content to satisfice, though the means to do better was reasonably transparent

Extreme Walrasian Dynamics: The Gale Example in the Lab

We study the classic Gale (1963) economy using laboratory markets. Tatonnement theory predicts prices will diverge from an equitable interior equilibrium towards infinity or zero depending only on initial prices. The inequitable equilibria determined by these dynamics give all gains from exchange to one side of the market. Our results show surprisingly strong support for these predictions. In most sessions one side of the market eventually outgains the other by more than twenty times, leaving the disadvantaged side to trade for mere pennies. We also find preliminary evidence that these dynamics are sticky, resisting exogenous interventions designed to reverse their trajectories

Aggregation and convergence in experimental general equilibrium economies constructed from naturally occurring preferences

Prior laboratory experiments have studied general equilibrium economies constructed from "induced preferences" for artificial goods. We introduce new methods that allow us to study economies constructed instead from subjects' actual, "homegrown" preferences. Our subjects reveal their preferences by choosing portfolios of Arrow securities from budget lines through fixed endowments for a series of prices. We then construct several different economies by sorting subjects according to their revealed preferences. The constructed economies exhibit a wide range of predicted outcomes, where predictions are competitive general equilibria given the revealed preferences. Perhaps surprisingly, in every one of our markets the predicted excess demand is well-behaved, and avoids the pathologies highlighted in the Sonnenschein-Mantel-Debreu theorem. (The main reason seems to be heterogeneity in revealed preferences.) Actual trade in the constructed economies using a tatonnement market institution closely tracks predictions in most markets. The exceptions occur in economies with severe wealth effects that generate excess demands that are flat relative to measured preference volatility

GDPR Impact on Computational Intelligence Research

The General Data Protection Regulation (GDPR) will become a legal requirement for all organizations in Europe from 25th May 2018 which collect and process data. One of the major changes detailed in Article 22 of the GDPR includes the rights of an individual not to be subject to automated decisionmaking, which includes profiling, unless explicit consent is given. Individuals who are subject to such decision-making have the right to ask for an explanation on how the decision is reached and organizations must utilize appropriate mathematics and statistical procedures. All data collected, including research projects require a privacy by design approach as well as the data controller to complete a Data Protection Impact Assessment in addition to gaining ethical approval. This paper discusses the impact of the GDPR on research projects which contain elements of computational intelligence undertaken within a University or with an Academic Partner

Learning Competitive Equilibrium

The epsilon-intelligent competitive equilibrium algorithm is a decentralized alternative to Walras' tatonnement procedure for markets to arrive at competitive equilibrium. We build on the Gode-Spear-Sunder zero-intelligent algorithm in which random generation of bids and offers from agents' welfare-enhancing opportunity sets generates Pareto optimal allocations in a pure exchange economy. We permit agents to know if they are subsidizing others at such allocations, and to veto such allocations, restricting the subsequent iterations of the algorithm only to those trades that are both Pareto-improving and provide strictly greater wealth, and ultimately utility, for such agents. In this simple institution actions of minimally intelligent agents based on local information can lead the market to approximate competitive equilibrium in a larger set of economies than the tatonnement process would allow. This helps address one of the major shortcomings of the Arrow-Debreu-McKenzie model with respect to the instability of tatonnement in an open set of economies. It also addresses the behavioral critique of mathematically derived equilibria for the inability of cognitively-limited humans to maximize. The proof of convergence of the algorithm presented here also provides a way of showing the existence of competitive equilibrium for monotonic, convex exchange economies with heterogeneous agents and many goods without application of a fixed-point theorem.

Exchange and Specialisation as a Discovery Process

In this article we study the performance of an economy that can support specialisation if the participants develop and follow some system of exchange. We define a closed economy in which the participants must discover the ability to exchange, implement it, and ascertain what they are comparatively advantaged in producing. Many of our participants demonstrate the ability to find comparative advantage, capture gains from trade and effectively choose production that is consistent with the choices of others. We explore various treatments to provide insight into the conditions that foster the growth of specialisation and exchange within this weak institutional framework

Follow-up observations of PTFO 8-8695: a 3 MYR old T Tauri star hosting a Jupiter-mass planetary candidate

We present Spitzer 4.5 μm light curve observations, Keck NIRSPEC radial velocity observations, and LCOGT optical light curve observations of PTFO 8-8695, which may host a Jupiter-sized planet in a very short orbital period (0.45 days). Previous work by van Eyken et al. and Barnes et al. predicts that the stellar rotation axis and the planetary orbital plane should precess with a period of 300-600 days. As a consequence, the observed transits should change shape and depth, disappear, and reappear with the precession. Our observations indicate the long-term presence of the transit events ( years), and that the transits indeed do change depth, disappear and reappear. The Spitzer observations and the NIRSPEC radial velocity observations (with contemporaneous LCOGT optical light curve data) are consistent with the predicted transit times and depths for the precession model and demonstrate the disappearance of the transits. An LCOGT optical light curve shows that the transits do reappear approximately 1 year later. The observed transits occur at the times predicted by a straight-forward propagation of the transit ephemeris. The precession model correctly predicts the depth and time of the Spitzer transit and the lack of a transit at the time of the NIRSPEC radial velocity observations. However, the precession model predicts the return of the transits approximately 1 month later than observed by LCOGT. Overall, the data are suggestive that the planetary interpretation of the observed transit events may indeed be correct, but the precession model and data are currently insufficient to confirm firmly the planetary status of PTFO 8-8695b

The Role of Retinoic Acid in Tolerance and Immunity

Vitamin A elicits a broad array of immune responses through its metabolite, retinoic acid (RA). Recent evidence indicates that loss of RA leads to impaired immunity, whereas excess RA can potentially promote inflammatory disorders. In this review, we discuss recent advances showcasing the crucial contributions of RA to both immunological tolerance and the elicitation of adaptive immune responses. Further, we provide a comprehensive overview of the cell types and factors that control the production of RA and discuss how host perturbations may affect the ability of this metabolite to control tolerance and immunity or to instigate pathology

SNAPSHOT USA 2019 : a coordinated national camera trap survey of the United States

This article is protected by copyright. All rights reserved.With the accelerating pace of global change, it is imperative that we obtain rapid inventories of the status and distribution of wildlife for ecological inferences and conservation planning. To address this challenge, we launched the SNAPSHOT USA project, a collaborative survey of terrestrial wildlife populations using camera traps across the United States. For our first annual survey, we compiled data across all 50 states during a 14-week period (17 August - 24 November of 2019). We sampled wildlife at 1509 camera trap sites from 110 camera trap arrays covering 12 different ecoregions across four development zones. This effort resulted in 166,036 unique detections of 83 species of mammals and 17 species of birds. All images were processed through the Smithsonian's eMammal camera trap data repository and included an expert review phase to ensure taxonomic accuracy of data, resulting in each picture being reviewed at least twice. The results represent a timely and standardized camera trap survey of the USA. All of the 2019 survey data are made available herein. We are currently repeating surveys in fall 2020, opening up the opportunity to other institutions and cooperators to expand coverage of all the urban-wild gradients and ecophysiographic regions of the country. Future data will be available as the database is updated at eMammal.si.edu/snapshot-usa, as well as future data paper submissions. These data will be useful for local and macroecological research including the examination of community assembly, effects of environmental and anthropogenic landscape variables, effects of fragmentation and extinction debt dynamics, as well as species-specific population dynamics and conservation action plans. There are no copyright restrictions; please cite this paper when using the data for publication.Publisher PDFPeer reviewe