Classification of poset-block spaces admitting MacWilliams-type identity

In this work we prove that a poset-block space admits a MacWilliams-type identity if and only if the poset is hierarchical and at any level of the poset, all the blocks have the same dimension. When the poset-block admits the MacWilliams-type identity we explicit the relation between the weight enumerators of a code and its dual.Comment: 8 pages, 1 figure. Submitted to IEEE Transactions on Information Theor

Bounds for complexity of syndrome decoding for poset metrics

In this work we show how to decompose a linear code relatively to any given poset metric. We prove that the complexity of syndrome decoding is determined by a maximal (primary) such decomposition and then show that a refinement of a partial order leads to a refinement of the primary decomposition. Using this and considering already known results about hierarchical posets, we can establish upper and lower bounds for the complexity of syndrome decoding relatively to a poset metric.Comment: Submitted to ITW 201

Exposure to Real Estate in Bank Portfolios

We implement a three-step procedure to assess the extent of exposure to real estate in commercial banks. First, we investigate the determinants of delinquency on real estate loans. We find the changes in interest rates and income to be the major determinants of aggregate delinquency rate. In the second step, we adopt a stress testing approach to calculate the potential impact on banks’ position of any adverse changes in these determinants. These calculations suggest that a 1.3 percentage point increase in mortgage interest rate leads to a 20% decrease in a typical bank’s distance to default. Finally, we look at the cross-sectional differences to identify the most vulnerable banks. Banks with rapid loan growth along with high cost-income ratio appear to be the most likely to experience a deterioration in their soundness.

Coding and Decoding Schemes for MSE and Image Transmission

In this work we explore possibilities for coding and decoding tailor-made for mean squared error evaluation of error in contexts such as image transmission. To do so, we introduce a loss function that expresses the overall performance of a coding and decoding scheme for discrete channels and that exchanges the usual goal of minimizing the error probability to that of minimizing the expected loss. In this environment we explore the possibilities of using ordered decoders to create a message-wise unequal error protection (UEP), where the most valuable information is protected by placing in its proximity information words that differ by a small valued error. We give explicit examples, using scale-of-gray images, including small-scale performance analysis and visual simulations for the BSMC.Comment: Submitted to IEEE Transactions on Information Theor

"White men can't jump," but would you bet on it?

We identify an otherwise efficient market in which racial stereotypes affect market outcomes. In this market, there are well-defined prices, well-defined outcomes, a finite time horizon, and readily available information. The market appears to efficiently process the available information, with the exception of the race of the participants. We examine data on point spreads for NBA games over the 15 seasons from 1993-94 to 2007-08. We find evidence that the racial composition of the team is related to the size of the spread and their performance against the spread. Specifically, we find that a more black team tends to face a larger point spread and that these teams perform worse against the spread. It is possible that this effect is driven by the bookmakers setting a biased point spread or driven by excessive betting on the more black team. Using a different data set containing the movement of the spread, we do not find a relationship between the movement of the spread and the racial composition of the team. As a result, we favor the explanation that the bookmakers set a biased point spread.Stereotypes; Point spread; Market efficiency

Liquidity and Dividend Policy

We document the association between a firm's payout policy and its stock's liquidity. In particular, we show that dividend-paying firms have a more liquid market for their stock and measures of a stock's liquidity is positively linked to its probability of being a dividend payer. Furthermore, this link between dividends and liquidity is stronger when shareholders are more powerful. This is consistent with a mechanism in which payout decisions act as a commitment not to invest: by distributing cash, the firm reduces its potential for internal equity financing, raising its cost of capital and leading to less investment. Such a mechanism may lead to less volatile stock prices and potentially to a decrease in the adverse selection costs faced by liquidity-constrained shareholders, increasing stock price liquidity. When shareholders have more power, liquidity would be more strongly linked with dividends as managers would be more likely to pay dividends to meet shareholders�preference for liquidity.Liquidity; Dividend Payers; Adverse Selection Costs; Corporate Governance; Shareholder Power; Informed Trading