Spanning embeddings of arrangeable graphs with sublinear bandwidth

The Bandwidth Theorem of B\"ottcher, Schacht and Taraz [Mathematische Annalen 343 (1), 175-205] gives minimum degree conditions for the containment of spanning graphs H with small bandwidth and bounded maximum degree. We generalise this result to a-arrangeable graphs H with \Delta(H)<sqrt(n)/log(n), where n is the number of vertices of H. Our result implies that sufficiently large n-vertex graphs G with minimum degree at least (3/4+\gamma)n contain almost all planar graphs on n vertices as subgraphs. Using techniques developed by Allen, Brightwell and Skokan [Combinatorica, to appear] we can also apply our methods to show that almost all planar graphs H have Ramsey number at most 12|H|. We obtain corresponding results for graphs embeddable on different orientable surfaces.Comment: 20 page

Perfect graphs of fixed density: counting and homogenous sets

For c in [0,1] let P_n(c) denote the set of n-vertex perfect graphs with density c and C_n(c) the set of n-vertex graphs without induced C_5 and with density c. We show that log|P_n(c)|/binom{n}{2}=log|C_n(c)|/binom{n}{2}=h(c)+o(1) with h(c)=1/2 if 1/4<c<3/4 and h(c)=H(|2c-1|)/2 otherwise, where H is the binary entropy function. Further, we use this result to deduce that almost all graphs in C_n(c) have homogenous sets of linear size. This answers a question raised by Loebl, Reed, Scott, Thomason, and Thomass\'e [Almost all H-free graphs have the Erd\H{o}s-Hajnal property] in the case of forbidden induced C_5.Comment: 19 page

How Code Words Work

This paper aims at giving a novel theory of code words. I start with an explanation of what code words are by introducing four primary features of them. Then, I turn to three major theories of code words: those offered by Stanley, Khoo, and Saul. I show how each of these theories falls short of giving a thorough account of all features of code words. Finally, drawing on these lessons, I will formulate a new theory which suggests that code words are polysemous

Public Works Programmes and Agricultural Risk: Evidence from India

The agricultural sectors in many low-and middle-income countries remain highly vulnerable to weather risk, a vulnerability that will only intensify under climate change. The globally trending public works programmes have the potential to impact weather-related agricultural risk. I explore the impact of India\u27s National Rural Employment Guarantee Act (NREGA) on weather-related agricultural risk. My empirical strategy explores the staggered roll-out of NREGA and random weather fluctuations. Using a nationwide panel of data, I find that NREGA makes crop yields more sensitive to low rainfall shocks. I posit that these results are consistent with a labour market channel, by which NREGA increases nonfarm labour supply in low rainfall years, and an income channel, by which NREGA leads to riskier agricultural practices. These results highlight the importance of understanding how social protection programmes shape agricultural risk

Can Farmers Adapt to Higher Temperatures? Evidence from India

Projections suggest that the damages from climate change will be substantial for developing countries. Understanding the ability of households in these countries to adapt to climate change is critical in order to determine the magnitude of the potential damages. In this paper, I investigate the ability of farmers in India to adapt to higher temperatures. I use a methodology that exploits short-term weather fluctuations as well as spatial variation in long-run climate. Specifically, I estimate how damaging high temperatures are for districts that experience high temperatures more or less frequently. I find that the losses from high temperatures are lower in heat-prone districts, a result that is consistent with adaptation. However, while adaptation appears to be modestly effective for moderate levels of heat, my results suggest that adaptation to extreme heat is much more difficult. Extremely high temperatures do grave damage to crops, even in places that experience these temperature extremes regularly. The persistence of negative impacts of high temperatures, even in areas that experience high temperatures frequently, underscores the need for development policies that emphasize risk mitigation and explicitly account for climate-change-related risks