On Approximating the Sum-Rate for Multiple-Unicasts

We study upper bounds on the sum-rate of multiple-unicasts. We approximate the Generalized Network Sharing Bound (GNS cut) of the multiple-unicasts network coding problem with $k$ independent sources. Our approximation algorithm runs in polynomial time and yields an upper bound on the joint source entropy rate, which is within an $O(\log^2 k)$ factor from the GNS cut. It further yields a vector-linear network code that achieves joint source entropy rate within an $O(\log^2 k)$ factor from the GNS cut, but \emph{not} with independent sources: the code induces a correlation pattern among the sources. Our second contribution is establishing a separation result for vector-linear network codes: for any given field $\mathbb{F}$ there exist networks for which the optimum sum-rate supported by vector-linear codes over $\mathbb{F}$ for independent sources can be multiplicatively separated by a factor of $k^{1-\delta}$, for any constant ${\delta>0}$, from the optimum joint entropy rate supported by a code that allows correlation between sources. Finally, we establish a similar separation result for the asymmetric optimum vector-linear sum-rates achieved over two distinct fields $\mathbb{F}_{p}$ and $\mathbb{F}_{q}$ for independent sources, revealing that the choice of field can heavily impact the performance of a linear network code.Comment: 10 pages; Shorter version appeared at ISIT (International Symposium on Information Theory) 2015; some typos correcte

A Stranger in the Night: Canadian Assistance to Southeastern Europe (1990-2005)

Official Development Assistance to the Balkans in the 1990-2005 period seem to reflect two different and contradictory donor 'geopolitical visions'. Some countries (like Greece and France) tended to consider the Balkans as a homogenized 'aid space'. On the contrary other countries (like Japan) or international organizations (like the European Union) tended to divide the Balkans into two 'aid spaces': the Western and the Eastern Balkans. The second 'geopolitical vision' led to differentiated aid policies. The Balkans were considered as being consisted of two groups of recipients: Western Balkans that received humanitarian and short-term reconstruction aid and Eastern Balkans that received more 'developmental' aid. In the last fifteen years the Balkans were one of the priority regions in Canada's foreign policy. Canada's military involvement in the Kosovo war was the largest military of the country since the Korean War. Also Canada has deployed an average of 1500-2000 peacekeepers at any given time in the Balkans and accepted more than 30.000 refugees from the region. But above all Canada provided hundreds of millions of $ for the reconstruction of the region. The paper focuses on Canada's bilateral aid to the Balkans, examines Canada's aid motives and attempts to identify the main differences between Canada's aid efforts in the region and those of other OECD countries. Above all the paper analyses Canada's regional geopolitical vision and tries to determine how its adoption influenced aid policy decisions

The crisis in Greece: the semi-rentier state hypothesis

This article offers an alternative explanation of the ‘Greek crisis’ by using the rentier-state theory. Past explanations referred to domestic pitfalls of the Greek economic development or to external constraints such as the incomplete architecture of the Eurozone. Without rejecting these interpretations, we offer a complementary interpretation underlining the facility and large scale with which external funds have flowed into Greece. This pattern was reminiscent of cases of resource-rich countries of the developing world and have created a semi-rentier state. External resources have spread a ‘rentier mentality’ among state actors and a ‘get-rich-quick mentality’ among business entrepreneurs and interest groups. Political decisions were characterised by riskaverse attitudes, while private actors spent their energy in seeking political protection rather than in initiating new enterprises. Three factors that played a significant role in shaping the Greek crisis and continue to plague Greece are foreign loans, EU funds and tax evasion