Quantization for Low-Rank Matrix Recovery

We study Sigma-Delta quantization methods coupled with appropriate reconstruction algorithms for digitizing randomly sampled low-rank matrices. We show that the reconstruction error associated with our methods decays polynomially with the oversampling factor, and we leverage our results to obtain root-exponential accuracy by optimizing over the choice of quantization scheme. Additionally, we show that a random encoding scheme, applied to the quantized measurements, yields a near-optimal exponential bit-rate. As an added benefit, our schemes are robust both to noise and to deviations from the low-rank assumption. In short, we provide a full generalization of analogous results, obtained in the classical setup of bandlimited function acquisition, and more recently, in the finite frame and compressed sensing setups to the case of low-rank matrices sampled with sub-Gaussian linear operators. Finally, we believe our techniques for generalizing results from the compressed sensing setup to the analogous low-rank matrix setup is applicable to other quantization schemes

Singing all the Way to the Bank: The Case for Economic Development through Music in Cape Verde

There has been an increasing awareness within the developed world that the cultural industries may play an important role in economic development. The fact that most of the commercial cultural industries have relatively low distribution costs, and that the gains from the mass production of a ‘hit’ recording can be substantial, have alerted policy makers to the possibility of a more dispersed location pattern; one that possibly need not concentrate at the core. Moreover, there is acknowledgement that all countries have a potential cultural heritage elements of which might be translated into cultural industries products; in fact, in a market place where novelty is king, new ideas and novel formulations are likely to be at the leading edge. Put simply, the cultural industries have been shown to be net positive contributors to economic growth; the cultural industries are not necessarily rooted in one place, production can move to the talent and visa versa; both can still have access to a market. Nations and regions that are able to make a contribution to cultural industries production may reap considerable local benefits. Cape Verde's prosperity resides in the intellectual capacity of its people; and Cape Verde’s history has many examples of how challenge and adversity can be transformed into hope and opportunity. Cesaria Evora put Cape Verde on the map for many people to listen to and enjoy: this has been welcomed news. The even better news is that Cape Verde has a seemingly never-ending source of talented singers and performers waiting to be discovered and promoted on the international scene, just like Brazil with its young soccer players. This paper will try to show how the development of a vibrant and active music industry in Cape Verde can provide this country with a medium for long term economic growth and development. It uses a few case studies to illustrate this point: Senegal, Austin, and Jamaica. Finally, it provides a way forward for what should be the key elements of a strategy that Cape Verdeans should develop to brand and build a globally competitive Cape Verdean Music industry.Cape Verde, Economic Development, Music

Is Lebanon’s Debt Sustainable? A Closer Look at Lebanon’s Debt Dynamics

1. Lebanon has one of the highest public debt stocks (relative to GDP) in the world, currently at over 185 percent of 2003 GDP. Economic policy continues to be dominated by chronic imbalances in government finances which have seen the budget deficit average over 17 percent of GDP over the past five years. 2. Recent data suggests that there are tentative signs of a certain reversal in direction of the overall debt-to-GDP ratio in Lebanon. The most recent IMF projections notes that lower financing costs and higher revenue and spending restraint have improved debt dynamics. However, in the absence of additional fiscal adjustment, and in an environment of rising interest rates, debt dynamics would again become unstable in the medium-to-long term. 3. Progress with many of the fiscal measures the government agreed to undertake in the context of Paris II has been poor, partly as a result of political bickering and the easing of the immediate pressure on the budget, sapping the reform programme of its urgency. Recent political developments ( the de facto sacking of Prime Minister Hariri after a bitter power struggle with President Lahoud and the passing of a critical resolution at the UN Security Council condemning the handling of the issue) only add to the uncertainty that the reform train will pick up steam anytime soon . 4. IMF previous medium-term projections of debt-to-GDP ratios for Lebanon in the Article IV context have been systematically over-optimistic and off-target. Projections done in 1994, 1996, 1997, 1999, and 2001 projected a conversion point in the debt-to-GDP curve within 2 to 3 years of the projection date. None of these conversion points materialized. The aim of this paper is to offer an alternative medium- term projection of the debt ratio, while trying to refine the judgment on variables and assumptions that enter into the projection. More specifically, more emphasis will be given to political and social factors that often through Lebanon’s history hindered or dwarfed any reform momentum. Consistent with a Debt Sustainability Analysis framework, a set of assumptions on public debt, primary balance, revenue and expenditure structure and trend, gross financing, and interest rate and growth dynamics will be formulated. The analysis will be complemented with a look at a reduced set of vulnerability indicators for public sector debt sustainability.Debt sustainability, Lebanon, Political economy

A Deterministic Analysis of Decimation for Sigma-Delta Quantization of Bandlimited Functions

We study Sigma-Delta ($\Sigma\Delta$) quantization of oversampled bandlimited functions. We prove that digitally integrating blocks of bits and then down-sampling, a process known as decimation, can efficiently encode the associated $\Sigma\Delta$ bit-stream. It allows a large reduction in the bit-rate while still permitting good approximation of the underlying bandlimited function via an appropriate reconstruction kernel. Specifically, in the case of stable $r$th order $\Sigma\Delta$ schemes we show that the reconstruction error decays exponentially in the bit-rate. For example, this result applies to the 1-bit, greedy, first-order $\Sigma\Delta$ scheme

Banking Sector Integration and Competition in CEMAC

This paper considers the extent of retail banking integration in the Communauté Economique et Monétaire d'Afrique Centrale (CEMAC) and the level of bank competition at the regional level. Using a mix of quantitative and qualitative indicators, the paper finds some evidence of price convergence in average interest rate spreads. However, this observed fact is not supported by an increase in cross-border flows in retail loans and deposits, and price convergence may merely reflect excess liquidity in the region. Other data also indicate that bank competition within the CEMAC as a region is limited, complementing the findings on integration. Addressing shortfalls in legal and regulatory frameworks, infrastructure, and markets would facilitate integration.Central African Economic and Monetary Community; Banks; Competition; Bank soundness; Financial soundness indicators; Monetary unions; Economic cooperation; CEMAC