Monday, 10 November 2014

Some recent papers on elasticity, resilience, and computational antifragility

Some of my most recent papers on elasticity, resilience, and computational antifragility:
  • "Antifragility = Elasticity + Resilience + Machine Learning. Models and Algorithms for Open System Fidelity". In Proc. of the 1st International Workshop "From Dependable to Resilient, from Resilient to Antifragile Ambients and Systems" (ANTIFRAGILE 2014), Hasselt, Belgium, 2-5 June, 2014. Elsevier Science, Procedia Computer Science.
    We introduce a model of the fidelity of open systems—fidelity being interpreted here as the compliance between corresponding figures of interest in two separate but communicating domains. A special case of fidelity is given by real-timeliness and synchrony, in which the figure of interest is the physical and the system’s notion of time. Our model covers two orthogonal aspects of fidelity, the first one focusing on a system’s steady state and the second one capturing that system’s dynamic and behavioural characteristics. We discuss how the two aspects correspond respectively to elasticity and resilience and we highlight each aspect’s qualities and limitations. Finally we sketch the elements of a new model coupling both of the first model’s aspects and complementing them with machine learning. Finally, a conjecture is put forward that the new model may represent a first step towards compositional criteria for antifragile systems.
  • "On the Behavioral Interpretation of System-Environment Fit and Auto-Resilience". In Proc. of the IEEE 2014 Conference on Norbert Wiener in the 21st Century, Boston, MA, 24-26 June, 2014. IEEE.
    Already 71 years ago Rosenblueth, Wiener, and Bigelow introduced the concept of the “behavioristic study of natural events” and proposed a classification of systems according to the quality of the behaviors they are able to exercise. In this paper we consider the problem of the resilience of a system when deployed in a changing environment, which we tackle by considering the behaviors both the system organs and the environment mutually exercise. We then introduce a partial order and a metric space for those behaviors, and we use them to define a behavioral interpretation of the concept of system-environment fit. Moreover we suggest that behaviors based on the extrapolation of future environmental requirements would allow systems to proactively improve their own system-environment fit and optimally evolve their resilience. Finally we describe how we plan to express a complex optimization strategy in terms of the concepts introduced in this paper
  • "Preliminary Contributions Towards Auto-Resilience". In A. Gorbenko, A. Romanovsky, V. Kharchenko (Eds). Software Engineering for Resilient Systems - 5th International Workshop, SERENE 2013, Kiev, Ukraine, October 3-4, 2013. Proceedings. LNCS 8166. Springer 2013.
    The variability in the conditions of deployment environments introduces new challenges for the resilience of our computer systems. As a response to said challenges, novel approaches must be devised so that identity robustness be guaranteed autonomously and with minimal overhead. This paper provides the elements of one such approach. First, building on top of previous results, we formulate a metric framework to compare specific aspects of the resilience of systems and environments. Such framework is then put to use by sketching the elements of a handshake mechanism between systems declaring their resilience figures and environments stating their minimal resilience requirements. Despite its simple formulation it is shown how said mechanism enables scenarios in which resilience can be autonomously enhanced, e.g., through forms of social collaboration. This paves the way to future “auto-resilient” systems, namely systems able to reason and revise their own architectures and organisations so as to optimally guarantee identity persistence.
  • "Quality indicators for collective systems resilience", Emergence: Complexity & Organization, ISSN: 1521-3250, Vol. 16, No. 3, September 2014, pp. 65-104.
    Resilience is widely recognized as an important design goal though it is one that seems to escape a general and consensual understanding. Often mixed up with other system attributes; traditionally used with different meanings in as many different disciplines; sought or applied through diverse approaches in various application domains, resilience in fact is a multi-attribute property that implies a number of constitutive abilities. To further complicate the matter, resilience is not an absolute property but rather it is the result of the match between a system, its current condition, and the environment it is set to operate in. In this paper we discuss this problem and provide a definition of resilience as a property measurable as a system-environment fit. This brings to the foreground the dynamic nature of resilience as well as its hard dependence on the context. A major problem becomes then that, being a dynamic figure, resilience cannot be assessed in absolute terms. As a way to partially overcome this obstacle, in this paper we provide a number of indicators of the quality of resilience. Our focus here is that of collective systems, namely those systems resulting from the union of multiple individual parts, sub-systems, or organs. Through several examples of such systems we observe how our indicators provide insight, at least in the cases at hand, on design flaws potentially affecting the efficiency of the resilience strategies. A number of conjectures are finally put forward to associate our indicators with factors affecting the quality of resilience.
  • "On the Constituent Attributes of Software and Organizational Resilience", Interdisciplinary Science Reviews, vol. 38, no. 2, Maney Publishing, June 2013.
    Our societies are increasingly dependent on the services supplied by our computers and their software. Forthcoming new technology is only exacerbating this dependence by increasing the number, the performance, and the degree of autonomy and inter-connectivity of software-empowered computers and cyber-physical “things”, which translates into unprecedented scenarios of interdependence. As a consequence, guaranteeing the persistence-of-identity of individual and collective software systems and software-backed organisations becomes an increasingly important prerequisite towards sustaining the safety, security, and quality of the computer services supporting human societies. Resilience is the term used to refer to the ability of a system to retain its functional and non-functional identity. In the present article we conjecture that a better understanding of resilience may be reached by decomposing it into a number of ancillary constituent properties, the same way as a better insight in system dependability was obtained by breaking it down into safety, availability, reliability, and other sub-properties. Three of the main sub-properties of resilience proposed here refer respectively to the ability to perceive environmental changes; to understand the implications introduced by those changes; and to plan and enact adjustments intended to improve the system-environment fit. A fourth property characterises the way the above abilities manifest themselves in computer systems. The four properties are then analyzed in three families of case studies, each consisting of three software systems that embed different resilience methods. Our major conclusion is that reasoning in terms of our resilience sub-properties may help revealing the characteristics—and in particular the limitations—of classic methods and tools meant to achieve system and organisational resilience. We conclude by suggesting that our method may prelude to meta-resilient systems—systems, that is, able to adjust optimally their own resilience with respect to changing environmental conditions.
  • "Community Resilience Engineering: Reflections and Preliminary Contributions". In I. Majzik and M. Vieira (Eds.), Proceedings of SERENE 2014, LNCS 8785, pp. 1-8, 2014
    An important challenge for human societies is that of mastering the complexity of Community Resilience, namely “the sustained ability of a community to utilize available resources to respond to, withstand, and recover from adverse situations”. The above concise definition puts the accent on an important requirement: a community’s ability to make use in an intelligent way of the available resources, both institutional and spontaneous, in order to match the complex evolution of the “significant multi-hazard threats characterizing a crisis”. Failing to address such requirement exposes a community to extensive failures that are known to exacerbate the consequences of natural and human-induced crises. As a consequence, we experience today an urgent need to respond to the challenges of community resilience engineering. This problem, some reflections, and preliminary prototypical contributions constitute the topics of the present article.
    A presentation of this paper is available here.
  • "Systems, Resilience, and Organization: Analogies and Points of Contact with Hierarchy Theory".
    Aim of this paper is to provide preliminary elements for discussion about the implications of the Hierarchy Theory of Evolution on the design and evolution of artificial systems and socio-technical organizations. In order to achieve this goal, a number of analogies are drawn between the System of Leibniz; the socio-technical architecture known as Fractal Social Organization; resilience and related disciplines; and Hierarchy Theory. In so doing we hope to provide elements for reflection and, hopefully, enrich the discussion on the above topics with considerations pertaining to related fields and disciplines, including computer science, management science, cybernetics, social systems, and general systems theory.
  • "Behavior, Organization, Substance: Three Gestalts of General Systems Theory". In Proc. of the IEEE 2014 Conference on Norbert Wiener in the 21st Century, Boston, MA, 24-26 June, 2014. IEEE.
    The term gestalt, when used in the context of general systems theory, assumes the value of “systemic touchstone”, namely a figure of reference useful to categorize the properties or qualities of a set of systems. Typical gestalts used, e.g., in biology, are those based on anatomical or physiological characteristics, which correspond respectively to architectural and organizational design choices in natural and artificial systems. In this paper we discuss three gestalts of general systems theory: behavior, organization, and substance, which refer respectively to the works of Wiener, Boulding, and Leibniz. Our major focus here is the system introduced by the latter. Through a discussion of some of the elements of the Leibnitian System, and by means of several novel interpretations of those elements in terms of today’s computer science, we highlight the debt that contemporary research still has with this Giant among the giant scholars of the past.