Month: January 2024

Complex Systems Summer School | Santa Fe Institute

Complex Systems Summer School (CSSS) offers an intensive four-week introduction to complex behavior in mathematical, physical, living, and social systems. CSSS brings together graduate students, postdoctoral fellows, and professionals to transcend disciplinary boundaries, take intellectual risks, and ask big questions about complex systems. The residential program comprises a series of lectures and workshops devoted to theory and tools, applications-focused seminars, and discussions with faculty and fellow participants. CSSS participants put what they learn from these didactic sessions into practice through group research projects, conducted throughout the program and often extending into manuscripts and longer-term collaborations. CSSS provides an unparalleled opportunity for early-career researchers to expand their professional networks, produce a novel research product, and gain valuable experience working in transdisciplinary teams.

More at: www.santafe.edu

Emergence and Causality in Complex Systems: A Survey on Causal Emergence and Related Quantitative Studies

Bing Yuan, Zhang Jiang, Aobo Lyu, Jiayun Wu, Zhipeng Wang, Mingzhe Yang, Kaiwei Liu, Muyun Mou, Peng Cui

Emergence and causality are two fundamental concepts for understanding complex systems. They are interconnected. On one hand, emergence refers to the phenomenon where macroscopic properties cannot be solely attributed to the cause of individual properties. On the other hand, causality can exhibit emergence, meaning that new causal laws may arise as we increase the level of abstraction. Causal emergence theory aims to bridge these two concepts and even employs measures of causality to quantify emergence. This paper provides a comprehensive review of recent advancements in quantitative theories and applications of causal emergence. Two key problems are addressed: quantifying causal emergence and identifying it in data. Addressing the latter requires the use of machine learning techniques, thus establishing a connection between causal emergence and artificial intelligence. We highlighted that the architectures used for identifying causal emergence are shared by causal representation learning, causal model abstraction, and world model-based reinforcement learning. Consequently, progress in any of these areas can benefit the others. Potential applications and future perspectives are also discussed in the final section of the review.

Read the full article at: arxiv.org

Scalable network reconstruction in subquadratic time

Tiago P. Peixoto
Network reconstruction consists in determining the unobserved pairwise couplings between N nodes given only observational data on the resulting behavior that is conditioned on those couplings — typically a time-series or independent samples from a graphical model. A major obstacle to the scalability of algorithms proposed for this problem is a seemingly unavoidable quadratic complexity of O(N2), corresponding to the requirement of each possible pairwise coupling being contemplated at least once, despite the fact that most networks of interest are sparse, with a number of non-zero couplings that is only O(N). Here we present a general algorithm applicable to a broad range of reconstruction problems that achieves its result in subquadratic time, with a data-dependent complexity loosely upper bounded by O(N3/2logN), but with a more typical log-linear complexity of O(Nlog2N). Our algorithm relies on a stochastic second neighbor search that produces the best edge candidates with high probability, thus bypassing an exhaustive quadratic search. In practice, our algorithm achieves a performance that is many orders of magnitude faster than the quadratic baseline, allows for easy parallelization, and thus enables the reconstruction of networks with hundreds of thousands and even millions of nodes and edges.

Read the full article at: arxiv.org

Ricard Sole on the Space of Cognitions – Sean Carroll

Octopuses, artificial intelligence, and advanced alien civilizations: for many reasons, it’s interesting to contemplate ways of thinking other than whatever it is we humans do. How should we think about the space of all possible cognitions? One aspect is simply the physics of the underlying substrate, the physical stuff that is actually doing the thinking. We are used to brains being solid — squishy, perhaps, but consisting of units in an essentially fixed array. What about liquid brains, where the units can move around? Would an ant colony count? We talk with complexity theorist Ricard Solé about complexity, criticality, and cognition.

Listen at: www.preposterousuniverse.com

The temporal and affective structure of living systems: A thermodynamic perspective

Mads J Dengsø

Adaptive Behavior Volume 32, Issue 1

Enactive approaches to cognitive science as well as contemporary accounts from neuroscience have argued that we need to reconceptualize the role of temporality and affectivity in minds. Far from being limited to special faculties, such as emotional mental states and timekeeping, these accounts argue that time and affect both constitute fundamental aspects of minds and cognition. If this is true, how should one conceptualize the relation between these two fundamental aspects? This paper offers a way to conceptualize and clarify the relation between temporality and affectivity when understood in this fundamental sense. In particular, the paper contributes to ongoing discussions of structural temporality and affectivity by combining enactive notions of self-maintenance with a thermodynamically informed view of the organization of living systems. In situating temporality and affectivity by way of their role for the maintenance of thermodynamic non-equilibrium, I will argue that temporality and affectivity should be regarded as two sides of the same coin—that is, two distinct ways of highlighting one and the same process. This process corresponds to the continued differentiation of organism and environment as functional poles of a living system. The temporal and affective structure of living systems may thus be seen as the warp and weft by which living systems maintain themselves in terms of thermodynamic non-equilibrium.

Read the full article at: journals.sagepub.com