Future Targets and Multiple Equilibria

Multiple Pareto-rankable equilibria may obtain in an overlapping generations model where consumers save to reach a fixed target. Existence and uniqueness conditions are discussed. The model displays excess consumption sensitivity to current income and perfect old-age insurance.Multiple equilibria, saving, overlapping generations, excess sensitivity.

TARGET SAVING IN AN OVERLAPPING GENERATIONS MODEL

We examine a model in which the utility function has been engineered so that it is optimal for consumers to aim for a fixed target level of retirement resources. In this case consumption displays excess sensitivity to current income as well as perfect old age insurance. In an overlapping generations model, this leads naturally to multiple and unstable equilibria. Under static expectations, it also leads to a well-defined dynamics, including possible historical traps, implosions involving ever-diminishing capital stock and ever-increasing interest rates, and the feasibility of optimal one-time interventions.Targets, history, excess sensitivity, static expectations, Rational Expectations, uniqueness

Target Saving In An Overlapping Generations Model

We examine a model in which the utility function has been engineered so that it is optimal for consumers to aim for a fixed target level of retirement resources. In this case consumption displays excess sensitivity to current income as well as perfect old age insurance. In an overlapping generations model, this leads naturally to multiple and unstable equilibria. Under static expectations, it also leads to a well-defined dynamics, including possible historical traps, implosions involving ever-diminishing capital stock and ever-increasing interest rates, and the feasibility of optimal one-time interventions.Targets, history, excess sensitivity, static expectations, rational expectations, uniqueness.

Trade, Growth and Increasing Returns to Infrastructure : The Role of the Sophisticated Monopolist

We model an economy with two final goods, manufactures produced under IRS and food. The scale economies in manufacturing are external (therefore compatible with perfect competition) and traceable to internal economies in the provision of an infrastructural service (the third sector of the economy). We examine the equilibria of this economy under both autarky and free trade. We thus revisit a theme with a voluminous literature, beginning with R. C. O. Matthews(1950) vintage classic and including, among others, Panagariya (1991), Krugman (1991), and Venables (1996). Much of this as well as our own work concerns multiple equilibria : it overlaps the development literature on poverty traps from Rosenstein Rodan (1943) to Murphy, Schleifer and Vishny (1989). We differ from this body of work in a major, and some minor, respects. We trace the source of increasing returns to infrastructure, and our focus is on the role of the infrastructure providers beliefs in determining the equilibrium and the fate of the economy. Internal economies in infrastructure provision ensure that it is non-competitive . We consider a pure monopoly. The infrastructure provider is of course aware of the impact of his decisions on the price of his services, but he may or may not appreciate their impact, on demand for labor (in a market where he competes with all other industrial and agricultural producers) and wages and induced effects on demand for infrastructure itself. He may in short be a nave or a sophisticated decision-maker. We model the nave infrastructure provider after Venables (1996). Venables portrays a producer of intermediates who derives the demand curve for his product on the assumption that his customers have already contracted for their purchases of other inputs, specifically labor. Similar beliefs on the part of our infrastructure provider generate an equilibrium that is unique in the closed economy. In the small open economy, on the other hand, equilibria, where they exist , will generally be multiple : at any world price, there will generally exist one at a low level with unexhausted scale economies and another at a high level where these have been exhausted.Increasing returns to scale, cognitive hierarchy, multiple equilibria, uniqueness, Cournot oligopoly

Utility functions, future consumption targets and subsistence thresholds

If the consumer’s risk aversion behavior varies intertemporally and if the risk aversion coefficient on future consumption becomes very large, the consumer tends to aim at a fixed future consumption target. A by-product is a reinterpretation of subsistence theories of consumption.

Trade, Growth and Increasing Returns to Infrastructure : The Role of the Sophisticated Monopolist

We consider a model of international trade with increasing returns in a non-traded input into industry, infrastructure, and show that the nature of equilibrium depends crucially on whether the infrastructure provider acts in a nave manner akin to a Level 1 agent in a cognitive hierarchy (C-H) model or in a more sophisticated manner. Infrastructure requires a fixed investment and is produced under decreasing marginal costs, and we model two possible market forms, monopoly and Cournot oligopoly with free entry both capable of generating pecuniary externalities in the manufacturing sector . Unlike most other work exploring the theme of increasing returns, we derive a unique closed economy equilibrium. In a small open economy, we show that with nave infrastructure provider(s), multiple equilibria obtain. In this event whether or not a small open economy becomes an industrial exporter depends crucially on the presence of unexhausted economies of scale, and it is possible to have equilibria where manufactures are exported in spite of the world price of manufactures being lower than the autarky price. With a more sophisticated infrastructure provider, however, even an open economy has a unique equilibrium, which for a wide range of parameter values also involves a greater degree of industrialization than any of the nave equilibria. For some parameter values, however, neither infrastructure nor manufacturing can develop and the economy remains totally agrarian.Increasing returns to scale, cognitive hierarchy, multiple equilibria, uniqueness, Cournot oligopoly

Trade, Growth and Increasing Returns to Infrastructure: The Role of the Sophisticated Monopolist

We consider a model of international trade with increasing returns in a non-traded input into industry, “infrastructure”, and show that the nature of equilibrium depends crucially on whether the infrastructure provider acts in a “naïve” manner – akin to a Level 1 agent in a cognitive hierarchy (C-H) model – or in a more sophisticated manner. Infrastructure requires a fixed investment and is produced under decreasing marginal costs, and we model two possible market forms, monopoly and Cournot oligopoly with free entry – both capable of generating pecuniary externalities in the manufacturing sector . Unlike most other work exploring the theme of increasing returns, we derive a unique closed economy equilibrium. In a small open economy, we show that with “naïve” infrastructure provider(s), multiple equilibria obtain. In this event whether or not a small open economy becomes an industrial exporter depends crucially on the presence of unexhausted economies of scale, and it is possible to have equilibria where manufactures are exported in spite of the world price of manufactures being lower than the autarky price. With a more sophisticated infrastructure provider, however, even an open economy has a unique equilibrium, which for a wide range of parameter values also involves a greater degree of industrialization than any of the “naïve” equilibria. For some parameter values, however, neither infrastructure nor manufacturing can develop and the economy remains totally agrarian.Increasing returns to scale, cognitive hierarchy, multiple equilibria, uniqueness, Cournot oligopoly.

Near-Optimal Distributed Approximation of Minimum-Weight Connected Dominating Set

This paper presents a near-optimal distributed approximation algorithm for the minimum-weight connected dominating set (MCDS) problem. The presented algorithm finds an $O(\log n)$ approximation in $\tilde{O}(D+\sqrt{n})$ rounds, where $D$ is the network diameter and $n$ is the number of nodes. MCDS is a classical NP-hard problem and the achieved approximation factor $O(\log n)$ is known to be optimal up to a constant factor, unless P=NP. Furthermore, the $\tilde{O}(D+\sqrt{n})$ round complexity is known to be optimal modulo logarithmic factors (for any approximation), following [Das Sarma et al.---STOC'11].Comment: An extended abstract version of this result appears in the proceedings of 41st International Colloquium on Automata, Languages, and Programming (ICALP 2014

The role of triplet excitons in enhancing polymer solar cell efficiency: a photo-induced absorption study

Inclusion of heavy metal atoms in a polymer backbone allows transitions between the singlet and triplet manifolds. Interfacial dissociation of triplet excitons constitutes a viable mechanism for enhancing photovoltaic (PV) efficiencies in polymer heterojunction-based solar cells. The PV efficiency from polymer solar cells utilizing a ladder-type poly (para-phenylene) polymer (PhLPPP) with trace quantity of Pd atoms and a fullerene derivative (PCBM) is much higher than its counterpart (MeLPPP) with no Pd atom. Evidence is presented for the formation of a weak ground-state charge-transfer complex (CTC) in the blended films of the polymer and PCBM, using photo-induced absorption (PIA) spectroscopy. The CTC state in MeLPPP:PCBM has a singlet character to it, resulting in a radiative recombination. In contrast, the CTC states in PhLPPP:PCBM are more localized with a triplet character. An absorption peak at 1.65 eV is observed in PhLPPP:PCBM blend in the PIA, which may be converted to weakly-bound polaron-pairs, contributing to the enhancement of PV efficiency.Comment: 19 pages, 11 figure