Equilibrium Existence in Bipartite Social Games: A Generalization of Stable Matchings

We prove existence of equilibria in bipartite social games, where players choose both a strategy in a game and a partner with whom to play the game. Such social games generalize the well-known marriage problem where players choose partners but do not take actions subsequent to matching.Social Games

On the Formation of Interaction Networks in Social Coordination Games

There are many situations where two interacting individuals can benefit from coordinating their actions. We examine the endogenous choice of partners in such social coordination games and the implications for resulting play. We model the interaction pattern as a network where individuals periodically have the discretion to add or sever links to other players. A player chooses whether to add or sever a link based on the (prospective) partner's past behavior. With such endogenous interaction patterns we see multiple stochastically stable states of play, including some that involve play of equilibria in the coordination game that are neither efficient nor risk dominant.

Social Games: Matching and the Play of Finitely Repeated Games

We examine a new class of games, which we call social games, where players not only choose strategies but also choose with whom they play. A group of players who are dissatisfied with the play of their current partners can join together and play a new equilibrium. This imposes new refinements on equilibrium play, where play depends on the relative populations of players in different roles, among other things. We also examine finite repetitions of games where players may choose to rematch in any period. Some equilibria of fixed-player repeated games cannot be sustained as equilibria in a repeated social game. Conversely, the set of repeated matching (or social) equilibria also includes some plays that are not part of any subgame perfect equilibrium of the corresponding fixed-player repeated games. We explore existence under different equilibrium definitions, as well as the relationship to renegotiation-proof equilibrium. It is possible for repeated matching equilibria to be completely distinct from renegotiation-proof equilibria, and even to be Pareto inefficient.Social games, Matching, Games, Repeated games, Renegotiation

Social Games: Matching and the Play of Finitely Repeated Games

We examine a new class of games, which we call social games, where players not only choose strategies but also choose with whom they play. A group of players who are dissatisfied with the play of their current partners can join together and play a new equilibrium. This imposes new refinements on equilibrium play, where play depends on the relative populations of players in different roles, among other things. We also examine finite repetitions of games where players may choose to rematch in any period. Some equilibria of fixed-player repeated games cannot be sustained as equilibria in a repeated social game. Conversely, the set of repeated matching (or social) equilibria also includes some plays that are not part of any subgame perfect equilibrium of the corresponding fixed-player repeated games. We explore existence under different equilibrium definitions, as well as the relationship to renegotiation-proof equilibrium. It is possible for repeated matching equilibria to be completely distinct from renegotiation-proof equilibria, and even to be Pareto inefficient.Social Games, Matching, Games, Repeated Games, Renegotiation

The Sensorimotor Approach to Color Perception and the Necessity of Socio-cultural Considerations for Color Naming

In this paper I argue against Kevin O’Regan’s claim that the “biological reflectance function” and its notion of “simple” colors naturally lead to a biologically consistent standard for species wide color naming. Although the simplicity of these colors may allow for easier apprehension, the notion that color simplicity will naturally lead to a consistent standard for the naming of basic color hues across a species is inconsistent with the idea of objective colors in the way that he portrays it. While it fixes many of the traditional explanatory issues surrounding color perception, it opens up new explanatory issues surrounding color. In response to this I argue that more emphasis must be put on the place of socio/cultural judgements and habits in the sensorimotor approach to color perception. In contrast to O’Regans assertion that culture follows natural tendencies to name certain colors, I argue that color naming follows socio-cultural considerations for color naming regardless of objectivity of color experience

EVALUATION OF THE COUPLED MODEL INTERCOMPARISON PROJECT PHASE 6 (CMIP6) HISTORICAL SIMULATIONS OF THE ARCTIC SEA ICE: PROGRESS, LIMITATIONS AND THEIR CAUSES

A decline of the Arctic sea ice in response to a warming climate is assessed in the historical sea ice simulations from state-of-the-art global climate models participating in Phase 6 of the Coupled Model Intercomparison Project (CMIP6). Accurate simulations of sea ice are important for projections of its regional and global effects on the air-sea exchanges, weather, and climate. The timing and rate of simulated sea ice decline is compared with available observations for sea ice area and volume. Analysis indicates multi-model means and long-term trends for these common sea ice metrics are well represented, but the individual CMIP6 model ability to represent the observed accelerated rate in sea ice decline remains a challenge. Local and regional sea ice biases are identified through spatial analysis metrics, like sea ice thickness distribution pattern and sea ice edge analysis. Large model spatial errors imply limitations in or lack of representation of some key physical processes. The oceanic heat transport (OHT) and its forcing of the pan-Arctic sea ice decline are examined as possible model limitations. CMIP6 models show a strong correlation between increasing OHT and decreasing sea ice trends but likely underestimate the northward OHT over the polar cap (70°–90°N). Isolating specific model limitations and identifying possible processes affecting them will guide future model improvements critical to our understanding and projection of Arctic climate change.Commander, United States NavyApproved for public release. Distribution is unlimited

Emulating the fast-start swimming performance of the chain pickerel (Esox niger) using a mechanical fish design

Submitted in partial fulfillment of the requirements for the degree of Master of Science in Oceanographic Engineering at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2006Mean maximum start-up accelerations and velocities achieved by the fast-start specialist, northern pike, are reported at 120 ms-2 and 4 ms-1, respectively (Harper and Blake, 1990). In this thesis, a simple mechanical system was created to closely mimic the startle response that produces these extreme acceleration events. The system consisted of a thin metal beam covered by a urethane rubber fish body. The mechanical fish was held in curvature by a restraining line and released by a pneumatic cutting mechanism. The potential energy in the beam was transferred into the fluid, thereby accelerating the fish. The fish motion was recorded and the kinematics analyzed while using a number of different tail shapes and materials. Performance of the mechanical fish was determined by maximum acceleration, peak and averaged maximum velocity, and hydrodynamic efficiency. Maximum start-up acceleration was calculated at 48 ms-2. Peak and averaged maximum velocity was calculated at 0.96 ms-1 and 0.8 ms-1, respectively. The hydrodynamic efficiency of the fish, calculated by the transfer of energy, was 11%. Flow visualization of the mechanical fast-start wake was also analyzed. The visualization uncovered two specific vortex-shedding patterns; a single and a double-vortex pattern are described

On the Formation of Interaction Networks in Social Coordination Games

There are many situations where two interacting individuals can benefit from coordinating their actions. We examine the endogenous choice of partners in such social coordination games and the implications for resulting play. We model the interaction pattern as a network where individuals periodically have the discretion to add or sever links to other players. With such endogenous interaction patterns we see multiple stochastically stable states of play, including some that involve play of equilibria in the coordination game that are neither efficient nor risk dominant. Thus the endogenous network structure not only has implications for the interaction pattern that emerges, but it also has a significant impact on the play in the coordination game relative to what would arise if the same interaction network were exogenous

Social Games: Matching and the Play of Finitely Repeated Games

We examine a new class of games, which we call social games, where players not only choose strategies but also choose with whom they play. A group of players who are dissatisfied with the play of their current partners can join together and play a new equilibrium. This imposes new refinements on equilibrium play, where play depends on the relative populations of players in different roles, among other things. We also examine finite repetitions of games where players may choose to rematch in any period. Some equilibria of fixed-player repeated games cannot be sustained as equilibria in a repeated social game. Conversely, the set of repeated matching (or social) equilibria also includes some plays that are not part of any subgame perfect equilibrium of the corresponding fixed-player repeated games. We explore existence under different equilibrium definitions, as well as the relationship to renegotiation-proof equilibrium. It is possible for repeated matching equilibria to be completely distinct from renegotiationproof equilibria, and even to be Pareto inefficient

Space Suit Portable Life Support System (PLSS) 2.0 Unmanned Vacuum Environment Testing

For the first time in more than 30 years, an advanced space suit Portable Life Support System (PLSS) design was operated inside a vacuum chamber representative of the flight operating environment. The test article, PLSS 2.0, was the second system-level integrated prototype of the advanced PLSS design, following the PLSS 1.0 Breadboard that was developed and tested throughout 2011. Whereas PLSS 1.0 included five technology development components with the balance the system simulated using commercial-off-the-shelf items, PLSS 2.0 featured first generation or later prototypes for all components less instrumentation, tubing and fittings. Developed throughout 2012, PLSS 2.0 was the first attempt to package the system into a flight-like representative volume. PLSS 2.0 testing included an extensive functional evaluation known as Pre-Installation Acceptance (PIA) testing, Human-in-the-Loop testing in which the PLSS 2.0 prototype was integrated via umbilicals to a manned prototype space suit for 19 two-hour simulated EVAs, and unmanned vacuum environment testing. Unmanned vacuum environment testing took place from 1/9/15-7/9/15 with PLSS 2.0 located inside a vacuum chamber. Test sequences included performance mapping of several components, carbon dioxide removal evaluations at simulated intravehicular activity (IVA) conditions, a regulator pressure schedule assessment, and culminated with 25 simulated extravehicular activities (EVAs). During the unmanned vacuum environment test series, PLSS 2.0 accumulated 378 hours of integrated testing including 291 hours of operation in a vacuum environment and 199 hours of simulated EVA time. The PLSS prototype performed nominally throughout the test series, with two notable exceptions including a pump failure and a Spacesuit Water Membrane Evaporator (SWME) leak, for which post-test failure investigations were performed. In addition to generating an extensive database of PLSS 2.0 performance data, achievements included requirements and operational concepts verification, as well as demonstration of vehicular interfaces, consumables sizing and recharge, and water quality control