scholarly journals The Value of Incumbency When Platforms Face Heterogeneous Customers

2020 ◽  
Vol 12 (4) ◽  
pp. 229-269
Author(s):  
Gary Biglaiser ◽  
Jacques Crémer
Keyword(s):  
Dynamic Model ◽  
Network Externalities ◽  
Market Outcomes ◽  
Dynamic Framework ◽  
Static Models ◽  
Heterogeneous Consumers

We study competition for the market in a dynamic model with network externalities, focusing on the efficiency of market outcomes. We propose a representation of the strategic advantages of incumbency and embed it in a dynamic framework with heterogeneous consumers. Then, we completely identify the conditions under which inefficient equilibria with several platforms emerge at equilibrium; explore the reasons why these inefficient equilibria arise; and compute the value of incumbency and analyze why static models generally exaggerate it. (JEL D43, D62, L13, L86)

Afterthoughts in Greek: Gender mismatches under a dynamic framework

2016 ◽  
Vol 53 (2) ◽  
pp. 279-325 ◽  
Author(s):  
STERGIOS CHATZIKYRIAKIDIS
Keyword(s):  
Dynamic Model ◽  
Main Claim ◽  
Dynamic Framework ◽  
Core Components ◽  
Reconstruction Effects ◽  
General Perspective

This paper deals with the syntax of afterthoughts in Greek under a parsing-oriented perspective. The main claim is that afterthoughts can receive a straightforward explanation once we make the assumption that afterthoughts can be seen as answers to implicit questions. A formal syntactic account based on this assumption is put forth, and its ability to deal with gender mismatches exhibited in Greek afterthoughts is shown. Afterthoughts are further discussed in a more general perspective, arguing that once we turn into a dynamic model where context re-use and update are taken to be core components of syntax, a number of issues regarding afterthoughts like connectivity effects, locality constraints, freedom of positioning and reconstruction effects can receive a straightforward explanation.

Adaptation to the International Pollutant Control in Dynamic Framework

2013 ◽  
Vol 739 ◽  
pp. 361-364
Author(s):  
Xian Jiao Lv ◽  
Xiao Yan Zou
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Nash Equilibrium ◽  
Dynamic Model ◽  
Optimal Trajectory ◽  
Static Model ◽  
Control Problems ◽  
Global Optimality ◽  
Dynamic Framework

Most analysis of global warming are seldom analyses the countries adaptability to the climate change but may have an impact on the strategy of tackling global worming. Even if considered the influence, just works with the simple static model and not the dynamic model to analyze. This study is considering adaptation that is crucial for the analysis of the pollutant control problems in the dynamic framework. We show that the optimal trajectory and stock in the global optimality and Nash equilibrium respectively.

scholarly journals Is modelling complexity always needed? Insights from modelling PrEP introduction in South Africa

2020 ◽  
Vol 42 (4) ◽  
pp. e551-e560 ◽  
Author(s):  
Hannah Grant ◽  
Anna M Foss ◽  
Charlotte Watts ◽  
Graham F Medley ◽  
Zindoga Mukandavire
Keyword(s):  
South Africa ◽  
Condom Use ◽  
Dynamic Model ◽  
Hiv Risk ◽  
Dynamic Models ◽  
Static Model ◽  
Hiv Intervention ◽  
Time Horizons ◽  
Static Models ◽  
The Impact

Abstract Background Mathematical models can be powerful policymaking tools. Simple, static models are user-friendly for policymakers. More complex, dynamic models account for time-dependent changes but are complicated to understand and produce. Under which conditions are static models adequate? We compare static and dynamic model predictions of whether behavioural disinhibition could undermine the impact of HIV pre-exposure prophylaxis (PrEP) provision to female sex workers in South Africa. Methods A static model of HIV risk was developed and adapted into a dynamic model. Both models were used to estimate the possible reduction in condom use, following PrEP introduction, without increasing HIV risk. The results were compared over a 20-year time horizon, in two contexts: at epidemic equilibrium and during an increasing epidemic. Results Over time horizons of up to 5 years, the models are consistent. Over longer timeframes, the static model overstates the tolerated reduction in condom use where initial condom use is reasonably high ($\ge$50%) and/or PrEP effectiveness is low ($\le$45%), especially during an increasing epidemic. Conclusions Static models can provide useful deductions to guide policymaking around the introduction of a new HIV intervention over short–medium time horizons of up to 5 years. Over longer timeframes, static models may not sufficiently emphasise situations of programmatic importance, especially where underlying epidemics are still increasing.

Combustor-inlet interactions in a low-order dynamic model of ramjet engines

2020 ◽  
Vol 124 (1282) ◽  
pp. 2001-2018
Author(s):  
K. Liu ◽  
T. Cui
Keyword(s):  
Nonlinear Dynamics ◽  
Dynamic Model ◽  
Nonlinear Effects ◽  
Physical Parameters ◽  
Nonlinear Phenomena ◽  
Stable States ◽  
Dynamic Framework ◽  
Ramjet Engine ◽  
Multiple Stable States ◽  
Ramjet Engines

ABSTRACTThe coexistence of multiple stable states is indicative of self-organising processes occurring in the course of the combustor-inlet interactions in a ramjet engine and give rise to the appearance of various nonlinear phenomena. This paper provides a dynamic model that can describe the multiple stable states and the corresponding nonlinear effects to further investigate the dynamic interactions between combustor and inlet in a ramjet engine. Our study shows the whole engine can display distinct dynamic behaviours ranging from irreversibility to hysteresis and to various mode transitions, depending on different physical parameters. With the model, we also illustrate the role of the instability of the normal shock wave in impacting the whole engine’s nonlinear dynamics. Additionally, we extend the previous studies of the classification of combustor-inlet interactions from a static framework to a dynamic framework, which helps to clarify the transient processes of the nonlinear interactions. This work offers a quantitative illustration of the combustor-inlet interactions in a ramjet engine by revealing its nonlinear dynamics and associated characteristics, therefore advancing our understanding of the nonlinear phenomena that exhibit in ramjet engines.

Optimal Timing of Policy Announcements in Dynamic Election Campaigns*

2020 ◽  
Vol 135 (3) ◽  
pp. 1725-1797
Author(s):  
Yuichiro Kamada ◽  
Takuo Sugaya
Keyword(s):  
Dynamic Model ◽  
Optimal Timing ◽  
Election Campaign ◽  
Election Campaigns ◽  
Policy Space ◽  
Policy Positions ◽  
Static Models ◽  
Long Time

Abstract We construct a dynamic model of election campaigns. In the model, opportunities for candidates to refine/clarify their policy positions are limited and arrive stochastically along the course of the campaign until the predetermined election date. We show that this simple friction leads to rich and subtle campaign dynamics. We first demonstrate these effects in a series of canonical static models of elections that we extend to dynamic settings, including models with valence and a multidimensional policy space. We then present general principles that underlie the results from those models. In particular, we establish that candidates spend a long time using ambiguous language during the election campaign in equilibrium.

Modelling a Single-Wheel Testbed for Planetary Rover Applications

2010 ◽  
Author(s):  
Rishad A. Irani ◽  
Robert J. Bauer ◽  
Andrew Warkentin
Keyword(s):  
Dynamic Model ◽  
Sandy Soil ◽  
Dynamic Effect ◽  
Soil Deformation ◽  
Planetary Rover ◽  
New Model ◽  
Static Models ◽  
Force Data

This paper presents a dynamic model for a smooth wheel travelling through loose sandy soil. Many models that are used for such wheel-soil interactions are typically static or quasi-static models. The new model builds upon these widely-used models by adding the dynamic effect of the soil deformation. The new model is validated using experiments that were carried on a new single wheel testbed which was constructed at Dalhousie University. During experiments with a smooth wheel it was noticed that the track of the wheel had repeatable ridges. Moreover, it was noticed that the corresponding torque and force data also had oscillations in it with the periods of the harmonic coinciding with the ridges in the sand left by the track of the wheel.

Effects of public employment services on labor transitions: an analysis for the Spanish case

2014 ◽  
Vol 35 (7) ◽  
pp. 996-1015 ◽  
Author(s):  
Patricia Suárez ◽  
Begoña Cueto ◽  
Matías Mayor
Keyword(s):  
Dropout Prevention ◽  
Unobserved Heterogeneity ◽  
Multinomial Logit Model ◽  
International Standards ◽  
Public Employment ◽  
Market Outcomes ◽  
Employment Services ◽  
Content Type ◽  
Positive Effects ◽  
Dynamic Framework

Purpose – The purpose of this paper is to evaluate the influence of public employment services (PES) on transitions from unemployment. Design/methodology/approach – The likelihood of exit from unemployment is explained by a multinomial logit model which takes into account the target state of the transition (unemployment, employment or inactivity). In order to analyze the unobserved heterogeneity, the model has been estimated using a Generalized Linear Latent and Mixed Models. Findings – The analysis suggests that the contribution of PES to improving labor market outcomes is low in the case of transitions to employment. Nevertheless, PES play an important role in workforce dropout prevention. Practical implications – The results suggest that redesign and modernization are needed to improve PES performance. More intensive job counselling should be provided so that PES get beyond workforce dropout prevention and start having clear positive effects on placement. Target groups should be defined more clearly so as to ensure sustainable transitions for individuals at risk of exclusion. PES should focus on the most disadvantaged jobseekers and those who need more help to get jobs. Originality/value – First, the results highlight the role PES play in reducing inactivity rates. Second, this is the first study in Spain that uses Labor Force Survey (LFS) data to evaluate PES in a dynamic framework. The LFS is the only data source which allows us to relate people registered unemployed to people considered unemployed by international standards.

Models of English in the World

2014 ◽  
Author(s):  
Edgar W. Schneider
Keyword(s):  
Foreign Language ◽  
Dynamic Model ◽  
World Englishes ◽  
Family Tree ◽  
Conceptual Frameworks ◽  
Hub And Spoke ◽  
Deterministic Theory ◽  
The World ◽  
Static Models

This chapter systematically surveys conceptual frameworks (models) that have been suggested to identify similarities between World Englishes and to classify them accordingly. The earliest suggestions along these lines were static models, which either worked out historically based relationships between national varieties, having branched off in a family-tree-like manner, or classified countries based on whether English is used as a native, second or foreign language in them. Other early categorizations emphasized the global, national or regional outreach of varieties (in “hub-and-spoke” models) or variety types based on sociolinguistic settings in communities and their resulting linguistic properties. In contrast, recent models emphasize the evolutionary or even cyclic character of varieties; these include Trudgill’s deterministic theory and, very widely accepted nowadays, Schneider’s Dynamic Model, which is broadly outlined, including a brief discussion of some applications of and reactions to it.

To Trade, or not to Trade, that is the Question: New Roles for Incomplete Contracts in Dynamic Settings

2020 ◽  
Author(s):  
Yeon-Koo Che ◽  
József Sákovics
Keyword(s):  
Dynamic Model ◽  
Incomplete Contracts ◽  
Lessons Learned ◽  
Static Models ◽  
Cooperative Investment ◽  
Joint Ownership ◽  
Complementary Assets

Abstract We reexamine the role of incomplete contracts in a dynamic model of renegotiation that endogenizes the timing of investments and trade. The interaction between bargaining and investment significantly alters the lessons learned from static models. When the opportunity to trade is expected to be long lasting, contracts that exacerbate the parties’ absolute vulnerability to hold-up—especially following under-investment—are desirable. For example, joint ownership of complementary assets can be optimal, an exclusivity agreement can protect the investments of its recipient, and trade contracts can facilitate purely cooperative investment.

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