Emergence of size-structured dominance hierarchies through size-dependent feedback

Size-based dominance hierarchies influence fitness, group size and population dynamics and link dominance structure to evolutionary and ecological outcomes. While larger individuals often gain dominance, social status may influence growth and size in return, resulting in feedbacks among status, growth and size. Here, we present two models evaluating how these feedbacks influence the emergence of size structure in a dominance hierarchy. In the first, size influences competition for food and investment in suppressing growth of groupmates. Stable size differences emerged when suppression was greatest for similarly sized individuals and size had little effect on competition for food. The model predicted size divergence when size strongly affected competition for food. In the second model, we used a dynamic game to solve for optimal investment in growth suppression as a function of size structure. Investment in growth suppression was favoured only when dominants and subordinates were similar in size, generating size ratios different than those expected by chance. Variation in the feedbacks among growth, size and status can explain variation in emergent size structure of dominance hierarchies and its consequences for conflict within groups. This article is part of the theme issue ‘The centennial of the pecking order: current state and future prospects for the study of dominance hierarchies’.

Optimal Asset Allocation Subject to Withdrawal Risk and Solvency Constraints

This paper investigates the optimal asset allocation of a financial institution whose customers are free to withdraw their capital-guaranteed financial contracts at any time. In accounting for the asset-liability mismatch risk of the institution, we present a general utility optimization problem in a discrete-time setting and provide a dynamic programming principle for the optimal investment strategies. Furthermore, we consider an explicit context, including liquidity risk, interest rate, and credit intensity fluctuations, and show by numerical results that the optimal strategy improves both the solvency and asset returns of the institution compared to a standard institutional investor’s asset allocation.

Pricing strategy and product quality design with platform-investment

<p style='text-indent:20px;'>With the development of business, more consumers are quality sensitive and improving the product quality becomes particularly important. We mainly discuss two investment strategies: retailer-investment and platform-investment. Compared with non-investment case, only if consumer sensitivity is not too high, it is profitable for the retailer to select retailer-investment. When both retailer-investment and platform-investment are viable, the choice of investment mechanism depends on the profit-sharing ratio. Particularly, if the ratio is within a certain range, the optimal investment strategy is platform-investment, achieving a triple-win outcome. Besides, to effectively alleviate the contradiction between the retailer's moral hazard problem and the sustainable value-added effect of platform-investment, we further research the contract term. These results give us some meaningful management inspirations in investment mechanism.</p>

THE REALITY OF THE EVALUATION OF EDUCATIONAL PERFORMANCE IN THE LIGHT OF THE COMPETENCY-BASED APPROACH

Scientific research endeavors to provide theoretical approaches to various fields and fields, It has been valued by field applications in experimental and descriptive studies on samples planned in several environments, In the pursuit of effective learning through an optimal investment of the learner's environment and its pillars, and by extending the activities of the school outside, from hypothetical problems to real problems of the reality of the learner life. The philosophy of the competency-based approach and its procedures were based on constructive steps to achieve the above, However, she stood on a deep challenge depicted in the assessment, When all the activities are based on the learner's use of his experiences to respond to all the situations he is confronted with, It is therefore a continuous process of evaluation. before that; This research presents a theoretical approach to evaluation in general, with a focus on evaluation in the pedagogy of the competency-based approach, Highlight its foundations, its theoretical background and its practical difficulties, while promoting research with an office approach between the theoretical aspect stipulated in the process and the real environment in which it takes place.

Research on Optimal Investment Reinsurance of Insurance Companies under Delayed Risk Model

The reinsurance and investment portfolio of insurance companies has always been a hot issue in insurance business. In insurance practice, it is inevitable for insurance companies to invest their own funds in order to expand their capital scale and enhance market competitiveness so as to obtain greater returns. At the same time, in order for insurance companies to disperse insurance risks and to avoid too concentrated claims or catastrophes caused by failure to perform compensation responsibilities, the purchase of reinsurance business has also become an important way. Stochastic control theory is widely used in reinsurance and investment issues. Based on the reinsurance system architecture, this paper establishes a reinsurance delay risk investment model, which reduces the amount of claims to be borne by buying proportional reinsurance to avoid bankruptcy caused by the excessive amount of claims. By using the delayed venture capital model to describe the earnings of insurance companies, the optimal investment and reinsurance strategy are solved under the optimization criterion of minimizing the probability of bankruptcy. By analyzing the model parameter data, the influence of each parameter on optimal investment strategy and optimal reinsurance strategy is discussed.

Investing in water supply resilience considering uncertainty and management flexibility

This paper demonstrates how to make investment decisions that optimally improve water supply resilience, taking into consideration both future uncertainty and management flexibility. The demonstration is done by evaluating investment strategies for a 38 Ml/d water treatment plant serving an urban area with approximately 75 000 inhabitants, where there is uncertainty with respect to future population growth, industrial production, external demand and the amount of rainfall due to climate change. It is shown that the quantification and comparison of the possible reductions in service and intervention costs over comparably long periods enables the optimal investment decisions – that is, the ones with the optimal trade-offs between stakeholders. Additionally, it can be seen that the used methodology enables the consistent and transparent consideration of (a) the concerns of multiple stakeholders, (b) the future deep uncertainty associated with key concerns and (c) the flexibility of infrastructure managers to make decisions in the future using new information. The methodology also ensures that managers have clear plans of action and considerable insight into the extent of required future financing.

Robust equilibrium investment and reinsurance strategy with bounded memory and common shock dependence

In this paper, we consider the robust investment and reinsurance problem with bounded memory and risk co-shocks under a jump-diffusion risk model. The insurer is assumed to be ambiguity-averse and make the optimal decision under the mean-variance criterion. The insurance market is described by two-dimensional dependent claims while the risky asset is depicted by the jump-diffusion model. By introducing the performance in the past, we derive the wealth process depicted by a stochastic delay differential equation (SDDE). Applying the stochastic control theory under the game-theoretic framework, together with stochastic control theory with delay, the robust equilibrium investment-reinsurance strategy and the corresponding robust equilibrium value function are derived. Furthermore, some numerical examples are provided to illustrate the effect of market parameters on the optimal investment and reinsurance strategy.