Theorems of iteration g-contractive sequential composite mapping and periodic mapping in Banach or probabilistic Bannach space are proved, which allow some contraction ratios of the sequence of mapping might be larger...Theorems of iteration g-contractive sequential composite mapping and periodic mapping in Banach or probabilistic Bannach space are proved, which allow some contraction ratios of the sequence of mapping might be larger than or equal to 1, and are more general than the Banach contraction mapping theorem. Application to the proof of existence of solutions of cycling coupled nonlinear differential equations arising from prey-predator system and A&H stock prices are given.展开更多
Contract farming has been increasingly found to benefit smallholders in developing countries, yet much less is known about its role in the poultry industry where economies of scale could be more prominent. This study ...Contract farming has been increasingly found to benefit smallholders in developing countries, yet much less is known about its role in the poultry industry where economies of scale could be more prominent. This study aims to narrow this gap by analysing the choice of contract farming among Chinese broiler producers using a nationally representative survey. Simply cost-benefit analysis and multinomial logit regression modelling are jointly employed to explain contract farming decision making especially among small producers. In contrast to many recent studies, we find that small producers, though not passively excluded, usually opt out of contract farming due to limited profitability when large producers are coexistent. Such relationship is appropriately identified through a control function approach to correct for possible endogeneity. Therefore, contract farming may not help achieve higher welfare goals for small broiler producers who actually instead seek alternative market opportunities that better realise their comparative advantages.展开更多
文摘Theorems of iteration g-contractive sequential composite mapping and periodic mapping in Banach or probabilistic Bannach space are proved, which allow some contraction ratios of the sequence of mapping might be larger than or equal to 1, and are more general than the Banach contraction mapping theorem. Application to the proof of existence of solutions of cycling coupled nonlinear differential equations arising from prey-predator system and A&H stock prices are given.
基金supported by the earmarked fund for the Agricultural Science and Technology Innovation Program, Chinese Academy of Agricultural Sciences (ASTIPIAED-2017)the Modern Agro-industry Technology Research System, the Ministry of Agriculture of China (CARS-42-G24)
文摘Contract farming has been increasingly found to benefit smallholders in developing countries, yet much less is known about its role in the poultry industry where economies of scale could be more prominent. This study aims to narrow this gap by analysing the choice of contract farming among Chinese broiler producers using a nationally representative survey. Simply cost-benefit analysis and multinomial logit regression modelling are jointly employed to explain contract farming decision making especially among small producers. In contrast to many recent studies, we find that small producers, though not passively excluded, usually opt out of contract farming due to limited profitability when large producers are coexistent. Such relationship is appropriately identified through a control function approach to correct for possible endogeneity. Therefore, contract farming may not help achieve higher welfare goals for small broiler producers who actually instead seek alternative market opportunities that better realise their comparative advantages.
