Network configuration as a measure of power in global production networks

Power is one of the key components in understanding and analyzing global production and is central to the analytical frameworks of both GVCs and GPNs. By focusing on firms’ power within GPNs, we are able to draw a novel analytical link between the governance structures of GVCs and network configuration presented in recent versions of GPNs. Using global input- output data, we show that the network structure of global production helps determine the distribution of power among firms in different economic sectors and, consequently, it influences the governance structures of supply networks. More specifically, we find a very high correlation between the distribution of profits and a sector’s position in global production, captured by its (total strength) centrality. Based on this, we are able to provide a quantitative measure of power within global production and its governance structures

Efficient Computation of Sequence Mappability

Sequence mappability is an important task in genome re-sequencing. In the $(k,m)$-mappability problem, for a given sequence $T$ of length $n$, our goal is to compute a table whose $i$th entry is the number of indices $j \ne i$ such that length-$m$ substrings of $T$ starting at positions $i$ and $j$ have at most $k$ mismatches. Previous works on this problem focused on heuristic approaches to compute a rough approximation of the result or on the case of $k=1$. We present several efficient algorithms for the general case of the problem. Our main result is an algorithm that works in $\mathcal{O}(n \min\{m^k,\log^{k+1} n\})$ time and $\mathcal{O}(n)$ space for $k=\mathcal{O}(1)$. It requires a carefu l adaptation of the technique of Cole et al.~[STOC 2004] to avoid multiple counting of pairs of substrings. We also show $\mathcal{O}(n^2)$-time algorithms to compute all results for a fixed $m$ and all $k=0,\ldots,m$ or a fixed $k$ and all $m=k,\ldots,n-1$. Finally we show that the $(k,m)$-mappability problem cannot be solved in strongly subquadratic time for $k,m = \Theta(\log n)$ unless the Strong Exponential Time Hypothesis fails.Comment: Accepted to SPIRE 201

Too-big-to-fail banking in Europe : an enduring challenge

Is banking in the European Union still too-big-to-fail (TBTF)? We address this question by providing a critical overview of post- crisis banking regulation and examining whether financial markets continue to expect European governments to bailout TBTF banks. To the latter end we use a novel set of primary data, gathered from fieldwork in Europe, analyse credit ratings of TBTF banks, and compare them with the ratings of other European banks. Our results suggest that the expectation of government support for European banks is still present. Most notably, TBTF banks command a long-term credit rating about three notches higher than what would be the case in the absence of the expectation of government support. Other European banks enjoy significant rating uplifts too, albeit smaller in size

Optimal Computation of Overabundant Words

The observed frequency of the longest proper prefix, the longest proper suffix, and the longest infix of a word w in a given sequence x can be used for classifying w as avoided or overabundant. The definitions used for the expectation and deviation of w in this statistical model were described and biologically justified by Brendel et al. (J Biomol Struct Dyn 1986). We have very recently introduced a time-optimal algorithm for computing all avoided words of a given sequence over an integer alphabet (Algorithms Mol Biol 2017). In this article, we extend this study by presenting an O(n)-time and O(n)-space algorithm for computing all overabundant words in a sequence x of length n over an integer alphabet. Our main result is based on a new non-trivial combinatorial property of the suffix tree T of x: the number of distinct factors of x whose longest infix is the label of an explicit node of T is no more than 3n-4. We further show that the presented algorithm is time-optimal by proving that O(n) is a tight upper bound for the number of overabundant words. Finally, we present experimental results, using both synthetic and real data, which justify the effectiveness and efficiency of our approach in practical terms

Linear-Time Algorithm for Long LCF with k Mismatches

In the Longest Common Factor with k Mismatches (LCF_k) problem, we are given two strings X and Y of total length n, and we are asked to find a pair of maximal-length factors, one of X and the other of Y, such that their Hamming distance is at most k. Thankachan et al. [Thankachan et al. 2016] show that this problem can be solved in O(n log^k n) time and O(n) space for constant k. We consider the LCF_k(l) problem in which we assume that the sought factors have length at least l. We use difference covers to reduce the LCF_k(l) problem with l=Omega(log^{2k+2}n) to a task involving m=O(n/log^{k+1}n) synchronized factors. The latter can be solved in O(m log^{k+1}m) time, which results in a linear-time algorithm for LCF_k(l) with l=Omega(log^{2k+2}n). In general, our solution to the LCF_k(l) problem for arbitrary l takes O(n + n log^{k+1} n/sqrt{l}) time

Modernity and Contemporaneity

Modernity and Contemporaneity is the 3rd volume in the Hellenic-Serbian Philosophical Dialogue Series, a project that was initiated as an emphatic token of the will and commitment to establish permanent and fruitful collaboration between two strongly bonded Departments of Philosophy, this of the National and Kapodistrian University of Athens, and that of the University of Novi Sad respectively. This collaboration was founded from the very beginning upon friendship, mutual respect and strong engagement, as well us upon our firm resolution to establish a solid continuity in the editing project. The publication of this volume allows us to entertain feelings of contentment and confidence that this objective of the project has been accomplished.Publishe

Efficient computation of sequence mappability

Sequence mappability is an important task in genome resequencing. In the (k, m)-mappability problem, for a given sequence T of length n, the goal is to compute a table whose ith entry is the number of indices j≠ i such that the length-m substrings of T starting at positions i and j have at most k mismatches. Previous works on this problem focused on heuristics computing a rough approximation of the result or on the case of k= 1. We present several efficient algorithms for the general case of the problem. Our main result is an algorithm that, for k= O(1) , works in O(n) space and, with high probability, in O(n· min { mk, log kn}) time. Our algorithm requires a careful adaptation of the k-errata trees of Cole et al. [STOC 2004] to avoid multiple counting of pairs of substrings. Our technique can also be applied to solve the all-pairs Hamming distance problem introduced by Crochemore et al. [WABI 2017]. We further develop O(n2) -time algorithms to compute all (k, m)-mappability tables for a fixed m and all k∈ { 0 , … , m} or a fixed k and all m∈ { k, … , n}. Finally, we show that, for k, m= Θ (log n) , the (k, m)-mappability problem cannot be solved in strongly subquadratic time unless the Strong Exponential Time Hypothesis fails. This is an improved and extended version of a paper presented at SPIRE 2018

Essays on the network structure of global production

This PhD Thesis focuses on the notion of positionality of economic agents. Specifically, it explores how the position of capital and labour in the interconnected production processes of the world economy allows for an alternative conceptualization of their power relations. Positionality, in general, reflects the structural advantages of actors due to their position in social and natural systems and it has been conceptually developed and analysed by different disciplines, like sociology, economic geography and network theory. Within the context of the literatures of Global Commodity Chains (GCC), Global Value Chains (GVC) and Global Production Networks (GPN), positionality expresses the topological characteristics of economic actors, within the abstract space that their interrelations generate, in terms of their geographical and functional specificities. The research questions of this Thesis concentrate on the explanatory power of positionality with respect to economic actors in the world economy. In other words, the present research explores how the governance structures of GCC and GVC, and the firm strategies of GPN, are reflected upon the topological and positional dimension of power, through the investigation of three hypotheses: a) the statistical properties of the topology of the abstract space shaped by buyer-supplier relations, reflect the typologies of governance structures found in the literature; b) the spatial-functional position of production processes in the global interdependent and interconnected economy is associated with inter-firm power; c) the bargaining power of labour is related to the importance of the work roles it performs in global production. The methodology employed in this Thesis is multidisciplinary, combining insights from both the ‘chain’ and ‘network’ frameworks found in economic geography and international political economy, as well as complex and network theory, and input-output analysis. The research path followed proposes a significant contribution to the literature of economic geography, international political economy, and industrial relations, highlighting the interdisciplinary link of positionality with respect to power relations. This research is the first attempt to quantitatively map and empirically measure the properties of governance structures in the world economy, reviving the interest in the quantitative aspects of the questions posed by economic geography and geographical political economy. Moreover, highlighting the importance of positionality in the analysis of power relations, a new research path is open for the literatures on international trade and the effects of globalisation, to strengthen their wide array of theoretical approaches and empirical econometric techniques