Tangled Nature: A model of emergent structure and temporal mode among co-evolving agents

Understanding systems level behaviour of many interacting agents is challenging in various ways, here we'll focus on the how the interaction between components can lead to hierarchical structures with different types of dynamics, or causations, at different levels. We use the Tangled Nature model to discuss the co-evolutionary aspects connecting the microscopic level of the individual to the macroscopic systems level. At the microscopic level the individual agent may undergo evolutionary changes due to mutations of strategies. The micro-dynamics always run at a constant rate. Nevertheless, the system's level dynamics exhibit a completely different type of intermittent abrupt dynamics where major upheavals keep throwing the system between meta-stable configurations. These dramatic transitions are described by a log-Poisson time statistics. The long time effect is a collectively adapted of the ecological network. We discuss the ecological and macroevolutionary consequences of the adaptive dynamics and briefly describe work using the Tangled Nature framework to analyse problems in economics, sociology, innovation and sustainabilityComment: Invited contribution to Focus on Complexity in European Journal of Physics. 25 page, 1 figur

Chiral Bronsted Acid-Catalyzed Enantioselective alpha-Amidoalkylation Reactions: A Joint Experimental and Predictive Study,

Enamides with a free NH group have been evaluated as nucleophiles in chiral Bronsted acid-catalyzed enantioselective alpha-amidoalkylation reactions of bicyclic hydroxylactams for the generation of quaternary stereocenters. A quantitative structure-reactivity relationship (QSRR) method has been developed to find a useful tool to rationalize the enantioselectivity in this and related processes and to orient the catalyst choice. This correlative perturbation theory (PT)-QSRR approach has been used to predict the effect of the structure of the substrate, nucleophile, and catalyst, as well as the experimental conditions, on the enantioselectivity. In this way, trends to improve the experimental results could be found without engaging in a long-term empirical investigation.Ministerio de Economia y Competitividad (CTQ2013-41229-P), IKERBASQUE foundation, Gobierno Vasco (IT-623-13) and Universidad del Pais Vasco/Euskal Herriko Unibertsitatea UPV/EHU are gratefully acknowledged for their financial support. Technical and human support provided by Servicios Generales de Investigacion SGIker (UPV/EHU, MINECO, GV/EJ, ERDF and ESF) is also acknowledged

A network model of interpersonal alignment in dialog

In dyadic communication, both interlocutors adapt to each other linguistically, that is, they align interpersonally. In this article, we develop a framework for modeling interpersonal alignment in terms of the structural similarity of the interlocutors’ dialog lexica. This is done by means of so-called two-layer time-aligned network series, that is, a time-adjusted graph model. The graph model is partitioned into two layers, so that the interlocutors’ lexica are captured as subgraphs of an encompassing dialog graph. Each constituent network of the series is updated utterance-wise. Thus, both the inherent bipartition of dyadic conversations and their gradual development are modeled. The notion of alignment is then operationalized within a quantitative model of structure formation based on the mutual information of the subgraphs that represent the interlocutor’s dialog lexica. By adapting and further developing several models of complex network theory, we show that dialog lexica evolve as a novel class of graphs that have not been considered before in the area of complex (linguistic) networks. Additionally, we show that our framework allows for classifying dialogs according to their alignment status. To the best of our knowledge, this is the first approach to measuring alignment in communication that explores the similarities of graph-like cognitive representations. Keywords: alignment in communication; structural coupling; linguistic networks; graph distance measures; mutual information of graphs; quantitative network analysi

The Hosoya Entropy of a Graph

This paper demonstrates properties of Hosoya entropy, a quantitative measure of graph complexity based on a decomposition of the vertices linked to partial Hosoya polynomials. Connections between the information content of a graph and Hosoya entropy are established, and the special case of Hosoya entropy of trees is investigated

Toward Measuring Network Aesthetics Based on Symmetry

In this exploratory paper, we discuss quantitative graph-theoretical measures of network aesthetics. Related work in this area has typically focused on geometrical features (e.g., line crossings or edge bendiness) of drawings or visual representations of graphs which purportedly affect an observer’s perception. Here we take a very different approach, abandoning reliance on geometrical properties, and apply information-theoretic measures to abstract graphs and networks directly (rather than to their visual representaions) as a means of capturing classical appreciation of structural symmetry. Examples are used solely to motivate the approach to measurement, and to elucidate our symmetry-based mathematical theory of network aesthetics

Ecological Non-equilibrium and Biological Conservation

[Abstract] How to establish efficient conservation actions and policies for the long-term persistence of ecological systems remains a challenge. Conservation biology was born as a discipline of crisis, targeting the recovery of altered ecosystems under the paradigms of equilibrium and ecological stability. However, we argue that the concepts of ecological equilibrium and balance still hinder wildlife managers from optimizing proper decision-making and correctly prioritizing conservation actions. This is still the case, despite the prevailing paradigm has recently shifted to a more realistic view of non-equilibrium dynamics in ecosystems, even in the absence of anthropogenic impacts. The challenge for managers and policymakers is now even greater. First, because non-equilibrium is the basis for the Darwinian adaptive response of ecosystems, and hence maintaining variance, rather than decreasing it, should be the target of conservation. Secondly, ecosystems show non-linear responses (e.g. transients and critical transitions), which hamper diagnosis and prediction. Even though we are unable to suggest solutions to this conundrum, we warn here about potential biases when conserving non-equilibrium ecosystems. We suggest that insights from island ecology and medical science may be helpful when dealing with non-equilibrium in applied conservation. Incorporating the advances of the discipline of complex systems into the conceptual framework of management and policymaking may also contribute to improving the prioritization of actions, especially regarding some agents of global change. Finally, we advocate for the strengthening of the feedback between ecologists (both theoretical and empirical) and conservation practitioners to improve our knowledge on how ecosystems respond to perturbations

Amoeba Techniques for Shape and Texture Analysis

Morphological amoebas are image-adaptive structuring elements for morphological and other local image filters introduced by Lerallut et al. Their construction is based on combining spatial distance with contrast information into an image-dependent metric. Amoeba filters show interesting parallels to image filtering methods based on partial differential equations (PDEs), which can be confirmed by asymptotic equivalence results. In computing amoebas, graph structures are generated that hold information about local image texture. This paper reviews and summarises the work of the author and his coauthors on morphological amoebas, particularly their relations to PDE filters and texture analysis. It presents some extensions and points out directions for future investigation on the subject.Comment: 38 pages, 19 figures v2: minor corrections and rephrasing, Section 5 (pre-smoothing) extende