Controlling edge dynamics in complex networks

The interaction of distinct units in physical, social, biological and technological systems naturally gives rise to complex network structures. Networks have constantly been in the focus of research for the last decade, with considerable advances in the description of their structural and dynamical properties. However, much less effort has been devoted to studying the controllability of the dynamics taking place on them. Here we introduce and evaluate a dynamical process defined on the edges of a network, and demonstrate that the controllability properties of this process significantly differ from simple nodal dynamics. Evaluation of real-world networks indicates that most of them are more controllable than their randomized counterparts. We also find that transcriptional regulatory networks are particularly easy to control. Analytic calculations show that networks with scale-free degree distributions have better controllability properties than uncorrelated networks, and positively correlated in- and out-degrees enhance the controllability of the proposed dynamics.Comment: Preprint. 24 pages, 4 figures, 2 tables. Source code available at http://github.com/ntamas/netctr

Hierarchical self-organization of non-cooperating individuals

Hierarchy is one of the most conspicuous features of numerous natural, technological and social systems. The underlying structures are typically complex and their most relevant organizational principle is the ordering of the ties among the units they are made of according to a network displaying hierarchical features. In spite of the abundant presence of hierarchy no quantitative theoretical interpretation of the origins of a multi-level, knowledge-based social network exists. Here we introduce an approach which is capable of reproducing the emergence of a multi-levelled network structure based on the plausible assumption that the individuals (representing the nodes of the network) can make the right estimate about the state of their changing environment to a varying degree. Our model accounts for a fundamental feature of knowledge-based organizations: the less capable individuals tend to follow those who are better at solving the problems they all face. We find that relatively simple rules lead to hierarchical self-organization and the specific structures we obtain possess the two, perhaps most important features of complex systems: a simultaneous presence of adaptability and stability. In addition, the performance (success score) of the emerging networks is significantly higher than the average expected score of the individuals without letting them copy the decisions of the others. The results of our calculations are in agreement with a related experiment and can be useful from the point of designing the optimal conditions for constructing a given complex social structure as well as understanding the hierarchical organization of such biological structures of major importance as the regulatory pathways or the dynamics of neural networks.Comment: Supplementary videos are to be found at http://hal.elte.hu/~nepusz/research/supplementary/hierarchy

Probability current in zero-spin relativistic quantum mechanics

We show that the antisymmetric spinor tensor representation of spin-0 relativistic quantum mechanics provides a conserved current with positive definite timelike component, interpretable as probability density. The construction runs in complete analogy to the spin-1/2 case, and provides an analogously natural one-particle Hilbert space description for spin 0. Except for the free particle, the obtained formulation proves to be inequivalent to the one based on the Klein--Gordon equation. The second quantized version may lead to new field theoretical interaction terms for zero-spin particles.Comment: 9 pages, no figures; material presented at the Zim\'anyi School, December 7-11, 2015, Budapest, Hungar

Taxonomic results of the Bryotrop expedition to Zaïre and Rwanda : 28., Lejeuneaceae ; a ramicolous collection

The treatment of non epiphyllous Lejeuneaceae taxa was published in the first part of the Central African BRYOTROP results (Pócs 1993b). Anyhow, a nice material collected on tiny twigs (partly from fallen canopy branches) from the W edge of Nyungwe Forest Reserve, in a wet type of montane rainforest at 2000 m altitude, remained unidentified

Geometric pluripotential theory on K\"ahler manifolds

Finite energy pluripotential theory accommodates the variational theory of equations of complex Monge-Amp\`ere type arising in K\"ahler geometry. Recently it has been discovered that many of the potential spaces involved have a rich metric geometry, effectively turning the variational problems in question into problems of infinite dimensional convex optimization, yielding existence results for solutions of the underlying complex Monge-Amp\`ere equations. The purpose of this survey is to describe these developments from basic principles

Symmetric Shannon capacity is the independence number minus 1

A symmetric variant of Shannon capacity is defined and computed.Comment: 4 pages, submitted to Electronic Journal of Combinatoric

Infrastructure networks and the competitiveness of the economy

This paper aims to examine how technical infrastructure networks may contribute to improving the competitiveness of the Hungarian economy. Consequently, our main question will be to establish how certain networks or sectors can promote competitiveness of the entire economy rather than how they could be more competitive in their own field. In the macroeconomic or regional sense competitiveness is interpreted as the entirety of safeguards and preconditions that provide a long term basis for success in a competitive market environment. The review of the economic, social, institutional and facility preconditions of competitiveness has highlighted that practically every component must be backed by a good system of relations: both strong, balanced internal relations promoting co-operation and external relations to assure outward linkages. Despite the above correlation, it would be a fallacy to assume that infrastructure networks as linking elements in general are factors per se improving competitiveness. In accordance with the level of development of the economy, the key forms of activity and the realistically attainable objectives, different linkages and service needs become key for the development of the economy in different stages

Global crises: Is the Keynesian recipe relevant if applied under a global governance?

Keynesian policy was quite successful in the post-war decades in Western Europe, but by the late 1960s lost its efficiency due to changes in conditions rather than its mistaken logic. The lesson from the first global crisis erupting in early 1970s and also from the subsequent several crises since then is that the increasing crisis propensity of the world economy is rooted in its inherent disequilibria stemming from deep inequalities, asymmetrical interdependencies and disintegrated socio-economic structures. In view of the failure of the prevailing methods of crisis management, particularly those undifferentiated, antisocial austerity measures corresponding to a neo-liberal monetarist concept which neglects this lesson, many economists prefer the Keynesian recipe. However, since global crises need global solution, and the spread of conspicuous consumption modify the demand constraint, its application must be adjusted to reality, and requires some global governance which may pave the way for a global oeco-social market economy