37 research outputs found
Computing Shapley Values for Mean Width in 3-D
The Shapley value is a common tool in game theory to evaluate the importance
of a player in a cooperative setting. In a geometric context, it provides a way
to measure the contribution of a geometric object in a set towards some
function on the set. Recently, Cabello and Chan (SoCG 2019) presented
algorithms for computing Shapley values for a number of functions for point
sets in the plane. More formally, a coalition game consists of a set of players
and a characteristic function with . Let be a uniformly random permutation of , and be
the set of players in that appear before player in the permutation
. The Shapley value of the game is defined to be . More intuitively,
the Shapley value represents the impact of player 's appearance over all
insertion orders. We present an algorithm to compute Shapley values in 3-D,
where we treat points as players and use the mean width of the convex hull as
the characteristic function. Our algorithm runs in time and
space. Our approach is based on a new data structure for a variant of
the dynamic convolution problem , where we want to answer
dynamically. Our data structure supports updating at position ,
incrementing and decrementing and rotating by . We present a data
structure that supports operations in time and
space. Moreover, the same approach can be used to compute the Shapley values
for the mean volume of the convex hull projection onto a uniformly random -subspace in time and space for a point set in
-dimensional space ()
Les effets de la culture sur les performances économiques et la dégradation des prairies
Cette Ă©tude est fondĂ©e sur des informations recueillies au cours dâenquĂȘtes sur des TibĂ©tains et des Mongols qui vivent dans une mĂȘme rĂ©gion (la rĂ©gion du lac Qinghai dans le Nord-Ouest de la Chine), pratiquent la mĂȘme religion et prĂ©sentent un mode de vie similaire. Il sâagira dâexaminer comment les diffĂ©rences culturelles entre ces deux groupes ethniques affectent leur intĂ©gration au marchĂ©, leur mode dâĂ©levage du bĂ©tail et le niveau de dĂ©gradation des pĂąturages. Nous constatons des diffĂ©rences culturelles fondamentales entre les groupes, lâimpact de lâattitude religieuse sur le rapport au marchĂ© apparaissant comme la force dominante qui explique le degrĂ© relativement Ă©levĂ© de dĂ©gradation des prairies parmi les mĂ©nages mongols
Effects of Culture on Economic Performance and Grassland Degradation
This study uses micro-level data gathered for Tibetans and Mongolians living in the same region (Qinghai Lake area in Northwest China) and having similar religion (Buddhism) and livelihoods (livestock raising) to examine how cultural differences between these two ethnic groups affect their integration into markets, their means of livestock production, and the extent of degradation of the grassland. We find significant cultural differences between the two ethnic groups, and conclude that the impact of religious attitudes on the market orientation of herder households is the dominating force explaining a relatively high degree of grassland degradation among Mongolian households
Les effets de la culture sur les performances économiques et la dégradation des prairies
Cette Ă©tude est fondĂ©e sur des informations recueillies au cours dâenquĂȘtes sur des TibĂ©tains et des Mongols qui vivent dans une mĂȘme rĂ©gion (la rĂ©gion du lac Qinghai dans le Nord-Ouest de la Chine), pratiquent la mĂȘme religion et prĂ©sentent un mode de vie similaire. Il sâagira dâexaminer comment les diffĂ©rences culturelles entre ces deux groupes ethniques affectent leur intĂ©gration au marchĂ©, leur mode dâĂ©levage du bĂ©tail et le niveau de dĂ©gradation des pĂąturages. Nous constatons des diffĂ©rences culturelles fondamentales entre les groupes, lâimpact de lâattitude religieuse sur le rapport au marchĂ© apparaissant comme la force dominante qui explique le degrĂ© relativement Ă©levĂ© de dĂ©gradation des prairies parmi les mĂ©nages mongols
Intelligent Omni-Surfaces for Full-Dimensional Wireless Communications: Principle, Technology, and Implementation
The recent development of metasurfaces has motivated their potential use for
improving the performance of wireless communication networks by manipulating
the propagation environment through nearly-passive sub-wavelength scattering
elements arranged on a surface. However, most studies of this technology focus
on reflective metasurfaces, i.e., the surface reflects the incident signals
towards receivers located on the same side of the transmitter, which restricts
the coverage to one side of the surface. In this article, we introduce the
concept of intelligent omni-surface (IOS), which is able to serve mobile users
on both sides of the surface to achieve full-dimensional communications by
jointly engineering its reflective and refractive properties. The working
principle of the IOS is introduced and a novel hybrid beamforming scheme is
proposed for IOS-based wireless communications. Moreover, we present a
prototype of IOS-based wireless communications and report experimental results.
Furthermore, potential applications of the IOS to wireless communications
together with relevant research challenges are discussed
Impact of land fragmentation on rice producer's technical efficiency in Southeast China
PRIFPRI4; Theme 3; Subtheme 3.2; Managing natural resources; Agriculture and Rural DevelopmentDSG
Impact of land fragmentation on rice producer's technical efficiency in Southeast China [In Chinese]
PRIFPRI3; ISI; Theme 3; Subtheme 3.2; Managing natural resources; Agriculture and Rural DevelopmentDSG
Impact of Land Institutional Factors on Farm Management and Soil Quality
Soil quality has important implications for sustainable agricultural development and food self-sufficiency in many developing countries. A decrease in soil nutrient stocks, one of the components of soil quality, necessitates more inputs and greater management skills in order to compensate for the reduction in nutrients availability. This is why the interaction of agricultural development and soil quality management attracts widespread attention from researchers. Applying plot level data on input/output, and a selected number of soil quality indicators and farm household level information, from the three villages, this paper examines the impact of land fragmentation and land tenure on soil management, the dynamic component of soil quality, crop husbandry and rice yield at plot level. A 2SLS econometric approach is applied to simultaneously estimate the interlinked relationships between these variables. From these results we conclude that land fragmentation does play a role in farm management practices and decisions. The land tenure status of a plot does not affect crop husbandry decisions on labor and herbicide use. Farmers on rented-in plots do, however, use more chemical fertilizers (phosphorus and potassium). This implies that farmers care more about short-term yields than about the built-up of long-term soil productivity. In order to sustain long-term soil productivity, measures should be taken to ensure that the prices for renting land reflect such soil investments