| 1. |
|
|
| 2. |
- Acemoglu, Daron, et al.
(författare)
-
Harmonic influence in largescale networks
- 2014. - 3
-
Ingår i: ACM SIGMETRICS Performance Evaluation Review. - : Association for Computing Machinery (ACM). - 0163-5999. - 9781450327893 ; 42, s. 24-24
-
Konferensbidrag (refereegranskat)
|
|
| 3. |
- Acemoglu, Daron, et al.
(författare)
-
Opinion fluctuations and disagreement in social networks
- 2013
-
Ingår i: Mathematics of Operations Research. - : Institute for Operations Research and the Management Sciences (INFORMS). - 0364-765X .- 1526-5471. ; 38:1, s. 1-27
-
Tidskriftsartikel (refereegranskat)abstract
- We study a tractable opinion dynamics model that generates long-run disagreements and persistent opinion fluctuations. Our model involves an inhomogeneous stochastic gossip process of continuous opinion dynamics in a society consisting of two types of agents: (1) regular agents who update their beliefs according to information that they receive from their social neighbors and (2) stubborn agents who never update their opinions and might represent leaders, political parties, or media sources attempting to influence the beliefs in the rest of the society. When the society contains stubborn agents with different opinions, the belief dynamics never lead to a consensus (among the regular agents). Instead, beliefs in the society fail to converge almost surely, the belief profile keeps on fluctuating in an ergodic fashion, and it converges in law to a nondegenerate random vector. The structure of the graph describing the social network and the location of the stubborn agents within it shape the opinion dynamics. The expected belief vector is proved to evolve according to an ordinary differential equation coinciding with the Kolmogorov backward equation of a continuous-time Markov chain on the graph with absorbing states corresponding to the stubborn agents, and hence to converge to a harmonic vector, with every regular agent's value being the weighted average of its neighbors' values, and boundary conditions corresponding to the stubborn agents' beliefs. Expected cross products of the agents' beliefs allow for a similar characterization in terms of coupled Markov chains on the graph describing the social network. We prove that, in large-scale societies, which are highly fluid, meaning that the product of the mixing time of the Markov chain on the graph describing the social network and the relative size of the linkages to stubborn agents vanishes as the population size grows large, a condition of homogeneous influence emerges, whereby the stationary beliefs' marginal distributions of most of the regular agents have approximately equal first and second moments.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Alutto, Martina, et al.
(författare)
-
On SIR epidemic models with feedback-controlled interactions and network effects
- 2021
-
Ingår i: ; , s. 5562-5567
-
Konferensbidrag (refereegranskat)abstract
- We study extensions of the classical SIR model of epidemic spread. First, we consider a single population modified SIR epidemics model in which the contact rate is allowed to be an arbitrary function of the fraction of susceptible and infected individuals. This allows one to model either the reaction of individuals to the information about the spread of the disease or the result of government restriction measures, imposed to limit social interactions and contain contagion. We study the effect of both smooth dependancies and discontinuities of the contact rate. In the first case, we prove the existence of a threshold phenomenon that generalizes the well-known dichotomy associated to the reproduction rate parameter in the classical SIR model. Then, we analyze discontinuous feedback terms using tools from sliding mode control. Finally, we consider network SIR models involving different subpopulations that interact on a contact graph and present some preliminary simulations of modified versions of the classic SIR network.
|
|
| 7. |
- Arditti, Laura, et al.
(författare)
-
Equilibria and learning dynamics in mixed network coordination/anti-coordination games
- 2021
-
Ingår i: ; , s. 4982-4987
-
Konferensbidrag (refereegranskat)abstract
- Whilst network coordination games and network anti-coordination games have received a considerable amount of attention in the literature, network games with coexisting coordinating and anti-coordinating players are known to exhibit more complex behaviors. In fact, depending on the network structure, such games may even fail to have pure-strategy Nash equilibria. An example is represented by the well-known matching pennies (discoordination) game.In this work, we first provide graph-theoretic conditions for the existence of pure-strategy Nash equilibria in mixed network coordination/anti-coordination games of arbitrary size. For the case where such conditions are met, we then study the asymptotic behavior of best-response dynamics and provide sufficient conditions for finite-time convergence to the set of Nash equilibria. Our results build on an extension and refinement of the notion of network cohesiveness and on the formulation of the new concept of network indecomposibility.
|
|
| 8. |
- Arditti, Laura, et al.
(författare)
-
Robust Coordination of Linear Threshold Dynamics on Directed Weighted Networks
-
Ingår i: IEEE Transactions on Automatic Control. - 0018-9286.
-
Tidskriftsartikel (refereegranskat)abstract
- We study dynamics in a network of interacting agents updating their binary states according to a time-varying threshold rule. Specifically, agents revise their state asynchronously by comparing the weighted average of the current states of their neighbors in the interaction network with possibly heterogeneous time-varying threshold values. Such thresholds are determined by an exogenous signal representing an external influence field modeling the different agents' biases towards one state with respect to the other one. We prove necessary and sufficient conditions for global stability of consensus equilibria, robustly with respect to the (constant or time-varying) external field. Our results apply to general weighted directed interaction networks and build on super-modularity properties of certain network coordination games whose best response dynamics coincide with the linear threshold dynamics. In particular, we introduce a novel notion of robust improvement paths for such games and characterize necessary and sufficient conditions for their existence.
|
|
| 9. |
- Ba, Qin, et al.
(författare)
-
Distributed optimal equilibrium selection for traffic flow over networks
- 2016
-
Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 9781479978861 ; 2016, s. 6942-6947
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we present two distributed algorithms to compute an equilibrium, that is optimal with respect to strictly convex and separable cost functions, for controlled traffic flow dynamics over networks under constant exogenous inflows. The dynamics is modeled in continuous time by the Cell Transmission Model and a non-FIFO Dynamic Network Loading Model, with traffic control. The two algorithms are adaptations of the alternating direct method of multipliers (ADMM) and the accelerated dual descent (ADD) method from network flow optimization literature. When the demand and supply inequality constraints in the uncontrolled dynamics are relaxed to be independent over links, the resulting feasible set is convex if the demand and supply functions are concave, thereby imparting convexity to the optimal equilibrium selection problem. Each point in the feasible set is an equilibrium for the original dynamics under appropriately designed control. For the ADMM method, explicit expressions for the primal update show that no auxiliary variables are necessary. Convergence analysis for the primal variables is also provided. The standard ADD method is extended to also incorporate non-negativity constraints on the density and flow variables, and demand and supply inequality constraints. Illustrative simulation results are also presented.
|
|
| 10. |
|
|
