Guaranteed Discovery of Control-Endogenous Latent States with Multi-Step Inverse Models

In many sequential decision-making tasks, the agent is not able to model the full complexity of the world, which consists of multitudes of relevant and irrelevant information. For example, a person walking along a city street who tries to model all aspects of the world would quickly be overwhelmed by a multitude of shops, cars, and people moving in and out of view, each following their own complex and inscrutable dynamics. Is it possible to turn the agent's firehose of sensory information into a minimal latent state that is both necessary and sufficient for an agent to successfully act in the world? We formulate this question concretely, and propose the Agent Control-Endogenous State Discovery algorithm (AC-State), which has theoretical guarantees and is practically demonstrated to discover the minimal control-endogenous latent state which contains all of the information necessary for controlling the agent, while fully discarding all irrelevant information. This algorithm consists of a multi-step inverse model (predicting actions from distant observations) with an information bottleneck. AC-State enables localization, exploration, and navigation without reward or demonstrations. We demonstrate the discovery of the control-endogenous latent state in three domains: localizing a robot arm with distractions (e.g., changing lighting conditions and background), exploring a maze alongside other agents, and navigating in the Matterport house simulator.Comment: Project Website: https://controllable-latent-state.github.io

Redirecting research efforts on the diversification-performance linkage: The search for synergy

We review the literature on the diversification-performance (D-P) relationship to a) propose that the time is ripe for a renewed attack on understanding the relationship between diversification and firm performance, and b) outline a new approach to attacking the question. Our paper makes four main contributions. First, through a review of the literature we establish the inherent complexities in the D-P relationship and the methodological challenges confronted by the literature in reaching its current conclusion of a non-linear relationship between diversification and performance. Second, we argue that to better guide managers the literature needs to develop along a complementary path – whereas past research has often focused on answering the big question of does diversification affect firm performance, this second path would focus more on identifying the precise micro-mechanisms through which diversification adds or subtracts value. Third, we outline a new approach to the investigation of this topic, based on (a) identifying the precise underlying mechanisms through which diversification affects performance; (b) identifying performance outcomes that are “proximate” to the mechanism that the researcher is studying, and (c) identifying an appropriate research design that can enable a causal claim. Finally, we outline a set of directions for future research

Natural history of endocrine failure in tropical chronic pancreatitis: a longitudinal follow-up study

Background and Aims: Diabetes in tropical chronic pancreatitis (TCP), also known as fibrocalculous pancreatic diabetes (FCPD), is frequently seen at diagnosis. The aim of the present study was to determine the natural history of endocrine failure in TCP subjects without diabetes at baseline. Methods: Of 73 TCP subjects without diabetes according to World Health Organization (WHO) criteria at baseline who were seen at an out-patient center, 54 (74.0%) underwent periodic oral glucose tolerance tests on follow up. Another 54 sex-matched, non-diabetic subjects without chronic pancreatitis served as controls. Baseline demographic and clinical characteristics were noted. Results: After a median follow up of 5.0 years in TCP subjects and 7.0 years in controls, 27 of 54 TCP subjects (50%) developed diabetes compared with 14 of 54 controls (25.9%). Of the TCP subjects, those who developed diabetes on follow up were older (31 ± 12 vs 23 ± 11 years; P = 0.013), had a higher body mass index (21.7 ± 4.4 vs 18.2 ± 3.5 kg/m2; P = 0.004), higher 2 h post-load plasma glucose (8.8 ± 1.9 vs 6.7 ± 1.4 mmol/L; P < 0.001) and lower fecal chymotrypsin (2.1 ± 1.2 vs 4.3 ± 2.5 U/g; P < 0.001) at baseline compared with those who did not develop diabetes. The median time for the development of diabetes after diagnosis of TCP was 9.6 years (compared with 14.4 years among controls). Only 2 of 13 TCP subjects (15.4%) who had undergone surgical interventions during the normal glucose tolerance phase developed diabetes during follow up. Conclusions: In TCP, there is progressive deterioration of endocrine pancreatic function, with development of diabetes in 50% of patients upon follow up, suggesting that FCPD is merely a later stage in the course of TCP. Early surgery may prevent the development of diabetes in TCP subjects