Unilateral and Multilateral Sanctions: A Network Approach

November 2017

Sumit Joshi and Ahmed Saber Mahmud 

IIEP Working Paper 2017-28 

Abstract: The extensive literature on efficacy of sanctions has been mainly focused on a dyadic interaction between sender and target. In contrast, this paper examines sanctions when the sender and target are embedded in a network of linkages to other agents and each agent’s utility is a function of the size of the agent’s component. Efficacy of sanctions is then a function of two factors: the network structure binding the sender and target, and the concavity/convexity of utility in the component size. We consider both unilateral sanctions and multilateral sanctions. We demonstrate how the network architecture, together with the specification of utility, qualifies and sometimes reverses the main tenets of the dyadic approach. We add to the recent work on identifying network architectures that sustain cooperation via the threat of exclusion by showing that the utility specification matters. Thus the same network can be efficacious for sanctions if utility is convex in component size but not if it is concave.

JEL: C72, D74, D85

Keywords: Unilateral sanctions, Multilateral sanction,  Sender, Target, Networks, Spanning trees, Cutsets

Network Formation with Multigraphs and Strategic Complementarities

November 2017

Sumit Joshi, Ahmed Saber Mahmud and Sudipta Sarangi

IIEP Working Paper 2017-27

Abstract: Economic agents are typically connected to others in multiple network relationships, and the architecture of one network could be shaped by connections in other networks. This paper examines the formation of one network when connections in a second network are inherited under two scenarios: (i) the inherited network is asymmetric allowing for a wide range of graphs called nested split graphs, and (ii) the inherited network is a symmetric type of network belonging to a subclass of regular graphs. Both the inherited and endogenously formed networks are interdependent because the respective actions in each are (weak) strategic complements. This property is su¢ cient to show that those who inherit high centrality will continue to have high centrality. Additionally, the network formed by the agents induces a coarser partition than the inherited network, suggesting the possibility of being able to improve network centrality, but only in a limited manner. Thus, our analysis explains preferential attachment and why inequality is often entrenched in society, how asymmetries in one network may be magnified or diminished in another, and what determines the identity of players occupying the various vertices of asymmetric equilibrium networks.

JEL: C72, D85

Keywords: Network formation, multigraphs, strategic complementarities, Katz-Bonacich centrality, nested split graphs.

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