Exploration and Exploitation of Victorian Science in Darwin's Reading Notebooks

Search in an environment with an uncertain distribution of resources involves a trade-off between exploitation of past discoveries and further exploration. This extends to information foraging, where a knowledge-seeker shifts between reading in depth and studying new domains. To study this decision-making process, we examine the reading choices made by one of the most celebrated scientists of the modern era: Charles Darwin. From the full-text of books listed in his chronologically-organized reading journals, we generate topic models to quantify his local (text-to-text) and global (text-to-past) reading decisions using Kullback-Liebler Divergence, a cognitively-validated, information-theoretic measure of relative surprise. Rather than a pattern of surprise-minimization, corresponding to a pure exploitation strategy, Darwin's behavior shifts from early exploitation to later exploration, seeking unusually high levels of cognitive surprise relative to previous eras. These shifts, detected by an unsupervised Bayesian model, correlate with major intellectual epochs of his career as identified both by qualitative scholarship and Darwin's own self-commentary. Our methods allow us to compare his consumption of texts with their publication order. We find Darwin's consumption more exploratory than the culture's production, suggesting that underneath gradual societal changes are the explorations of individual synthesis and discovery. Our quantitative methods advance the study of cognitive search through a framework for testing interactions between individual and collective behavior and between short- and long-term consumption choices. This novel application of topic modeling to characterize individual reading complements widespread studies of collective scientific behavior.Comment: Cognition pre-print, published February 2017; 22 pages, plus 17 pages supporting information, 7 pages reference

Identifying the Information Gain of a Quantum Measurement

We show that quantum-to-classical channels, i.e., quantum measurements, can be asymptotically simulated by an amount of classical communication equal to the quantum mutual information of the measurement, if sufficient shared randomness is available. This result generalizes Winter's measurement compression theorem for fixed independent and identically distributed inputs [Winter, CMP 244 (157), 2004] to arbitrary inputs, and more importantly, it identifies the quantum mutual information of a measurement as the information gained by performing it, independent of the input state on which it is performed. Our result is a generalization of the classical reverse Shannon theorem to quantum-to-classical channels. In this sense, it can be seen as a quantum reverse Shannon theorem for quantum-to-classical channels, but with the entanglement assistance and quantum communication replaced by shared randomness and classical communication, respectively. The proof is based on a novel one-shot state merging protocol for "classically coherent states" as well as the post-selection technique for quantum channels, and it uses techniques developed for the quantum reverse Shannon theorem [Berta et al., CMP 306 (579), 2011].Comment: v2: new result about non-feedback measurement simulation, 45 pages, 4 figure

Quantum Probability from Subjective Likelihood: improving on Deutsch's proof of the probability rule

I present a proof of the quantum probability rule from decision-theoretic assumptions, in the context of the Everett interpretation. The basic ideas behind the proof are those presented in Deutsch's recent proof of the probability rule, but the proof is simpler and proceeds from weaker decision-theoretic assumptions. This makes it easier to discuss the conceptual ideas involved in the proof, and to show that they are defensible.Comment: 23 pages. This is a modified version of my 2003 paper, which incorporates a completely rewritten and substantially improved proof of Equivalence as well as a few other more minor change

After the Bubble: The Survival and Ownership of Internet Marketplaces for Farmers and Agribusiness

This paper presents a theory of how industry structure and beliefs about Internet marketplace use have driven choice and ownership of marketplaces. The theory's predictions suggest that surviving Internet marketplaces will be those with strong historical linkages in an industry and those owned by or affiliated with major commodity buyers. Comparisons of these predictions with actual outcomes provide validation of the theory. Where predictions differ from results, observations are made as to the nature of the deviations.agricultural markets, electronic commerce, Internet markets, network externalities, technology adoption, Agribusiness,

A MODEL OF AGRICULTURAL INSURANCE IN EVALUATING ASYMMETRIC INFORMATION PROBLEMS

The main motivation for this paper is the recognition of the fact that asymmetric information is the form of moral hazard and adverse selection results in sizeable efficiency losses. These costs are passed back to producers in the form of excessively high premium rates and also passed back to the government via the crop insurance subsidy program. A secondary motivation stems from a recent debate in the literature regarding the specific effects of moral hazard on agricultural input use. Conventional wisdom suggests that moral hazard will induce producers to reduce input usage. A competing hypothesis has emerged which suggests that moral hazard may induce producers to increase their usage or risk increasing inputs. The main objective of this paper was to develop a model of agricultural insurance to understand why asymmetric information problems might exist and to compute and evaluate the relative program costs of agricultural insurance that can be attributed to moral hazard and adverse selection. These objectives are achieved by developing a theoretical model of agricultural insurance, and by conducting numerical simulations of the model. Simulation results indicated that insured farmers use less agricultural inputs than uninsured farmers in an attempt to maximize expected indemnities. Moral hazard was fould to be a significant problem only at higher coverage levels. Expected returns (in term of expected indemnities) to agricultural insurance were found to vary substantially between productivity (i.e., risk) types, and farmers were shown to recognize and respond to these differences. These results suggest that crop insurance is confronted with an adverse selection problem. Simulation results further indicated that program costs to a myopic insurer attributed to moral hazard and adverse selection could be substantial.Risk and Uncertainty,

Sequential Two-Player Games with Ambiguity

If players' beliefs are strictly non-additive, the Dempster-Shafer updating rule can be used to define beliefs off the equilibrium path. We define an equilibrium concept in sequential two-person games where players update their beliefs with the Dempster-Shafer updating rule. We show that in the limit as uncertainty tends to zero, our equilibrium approximates Bayesian Nash equilibrium by imposing context-dependent constraints on beliefs under uncertainty.