Impatience for Weakly Paretian Orders: Existence and Genericity

We study order theoretic and topological implications for impatience of weakly Paretian, representable orders on infinite utility streams. As a departure from the traditional literature, we do not make any continuity assumptions in proving the existence of impatient points. Impatience is robust in the sense that there are uncountably many impatient points. A general statement about genericity of impatience cannot be made for representable, weakly Paretian orders. This is shown by means of an example. If we assume a stronger sensitivity condition, then genericity obtains

Decision-making under risk: when is utility maximization equivalent to risk minimization?

Motivated by the analysis of a general optimal portfolio selection problem, which encompasses as special cases an optimal consumption and an optimal debt-arrangement problem, we are concerned with the questions of how a personality trait like risk-perception can be formalized and whether the two objectives of utility-maximization and risk-minimization can be both achieved simultaneously. We address these questions by developing an axiomatic foundation of preferences for which utility-maximization is equivalent to minimizing a utility-based shortfall risk measure. Our axiomatization hinges on a novel axiom in decision theory, namely the risk-perception axiom.Comment: Accepted for publication in Theory and Decisio

Ordering infinite utility streams: Efficiency, continuity, and no impatience

[EN]We study two related versions of the no-impatience postulate in the context of transitive and reflexive relations on infinite utility streams which are not necessarily complete. Both are excluded by the traditional (weak) anonymity axiom. We show explicit social welfare relations satisfying Strong Pareto and the weaker version of no-impatience that are compatible with continuity in all the traditional topologies in this field. However the stronger version of no-impatience is violated by all lower semicontinuous (in the sup or Campbell topologies) social welfare relations satisfying the Weak Pareto axiom

Price dispersion across online platforms: Evidence from hotel room prices in London (UK)

This paper studies the widespread price dispersion of homogeneous products across different online platforms, even when consumers can easily access price information from comparison websites. We collect data for the 200 most popular hotels in London (UK) and document that prices vary widely across booking sites while making reservations for a hotel room. Additionally, we find that prices listed across different platforms tend to converge as the booking date gets closer to the date of stay. However, the price dispersion persists until the date of stay, implying that the "law of one price" does not hold. We present a simple theoretical model to explain this and show that in the presence of aggregate demand uncertainty and capacity constraints, price dispersion could exist even when products are homogeneous, consumers are homogeneous, all agents have perfect information about the market structure, and consumers face no search costs to acquire information about the products. Our theoretical intuition and robust empirical evidence provide additional insights into price dispersion across online platforms in different institutional settings. Our study complements the existing literature that relies on consumer search costs to explain the price dispersion phenomenon.Comment: Accepted for publication in Applied Economic

Temperature induced phase transformation in Co

Temperature dependent phase transformation behavior in cobalt from hexagonal close-packed (hcp) to face centered cubic (fcc) has been found to be contradictory to that reported earlier. It is found that hcp phase stabilizes at both low and high temperature ($$\sim$$873 K) while fcc phase is stabilized at $$\sim$$500 K. At 298 K, hcp Co has been found to be predominant ($$\sim$$70%) where hcp magnetic phase is $$\sim$$60%. At 973 K, hcp phase is again predominant ($$\sim$$73%), but it is mainly the non-magnetic phase ($$\sim$$67%). Contrary to present results, it was found earlier that fcc phase was stabilized at high temperature and hcp to fcc transformation occured at $$\sim$$700 K. Present results from perturbed angular correlation measurements, therefore, requires a new theoretical interpretation for Co phase transformation. From present measurements, hyperfine magnetic fields in Co at room temperature for the hcp and fcc phases have been found to be 18.7(6) and 12.8(3) T, much lower than earlier reported results. The hyperfine magnetic fields at $$^{181}$$Ta impurity atom have been calculated by density functional theory (DFT) employing the full potential (linearized) augmented plane wave method (FP-LAPW). Present calculated results for both hcp and fcc phases corroborate our experimental results

Algorithms for weighted coloring problems

In this thesis, we studied a generalization of vertex coloring problem (VCP). A classical VCP is an assignment of colors to the vertices of a given graph such that no two adjacent vertices receive the same color. The objective is to find a coloring with the minimum number of colors. In the first part of the thesis, we studied the weighted version of the problem, where vertices have non-negative weights. In a weighted vertex coloring problem (WVCP) the cost of each color depends on the weights of the vertices assigned to that color and equals the maximum of these weights. Furthermore, in WVCP, the adjacent vertices are assigned different colors, and the objective is to minimize the total cost of all the colors used. We studied WVCP and proposed an O(n^2 log n) time algorithm for binary trees. Additionally, we studied WVCP in cactus paths. We proposed sub-quadratic and quadratic time algorithms for cactus paths. We studied a min-max regret version of the robust optimization where the weight of each vertex v is in the interval [w v , w v ]. The objective of is to find a coloring that has the minimum regret value. We proposed a linear time algorithm for robust coloring on bipartite graphs with uniform upper bound and arbitrary lower bound weights on the vertices. We also gave an integer linear programming (ILP) for the robust weighted vertex coloring problem (RWVCP). We solved a relaxation of the ILP formulation using column generation. We also gave an algorithm based on the branch and price method. Lastly, we performed experiments to study the quality of our algorithms.School of graduate studies, University of Lethbridge, PIMS, NSER