Notes on the Synthesis of Form by maverick architect/mathematician Christopher Alexander belongs to the canon of design theory. In 150 pages of youthful enthusiasm, Alexander brings together D’Arcy Thompson, cosmology, modernist architecture, anthropology, and his own algorithm to hierarchically decompose a graph. In 1962, two years before the publication of Notes on the Synthesis of Form, […]
Faraway, so close! Nobel prize to complex systems
Yesterday, it was announced that Syukuro Manabe, Klaus Hasselmann, and Giorgio Parisi get to share the 2021 Nobel prize in physics. Woo hoo! I had a smile on my lips running through the night streets of Tokyo (my usual exercise). The best part is the motivation: “For groundbreaking contributions to our understanding of complex physical […]
Universality: Stronger than logic
I was re-reading some old universality papers. You know, universality in the stat-mech sense—the critical exponents that characterize phase transitions are insensitive to details of your model or crystal structure of your material. This insight, allegedly flowing around in the stat-mech community in the 1960s, was first articulated by Robert Griffiths in 1970. It got […]
Minds, Machines and Herbert Simon
Our designed reality Two years late to the party, I discovered the brilliant review paper “Machine Behavior” by Iyad Rahwan and an all-star cast. Its premise is that we need to let systems relying on artificial intelligence be scientific study objects in their own right, even though they are, to some extent, engineered. The article […]
The watershed of feedbacks
This is a follow-up to my previous post about the differences between the traditions of integrative, systemsy science. I will use the same –5 to +5 scale as in that post. Negative numbers are not bad but represent people, papers, places, and concepts more to the complex systems / Santa Fe Institute side. Positive numbers […]
{complex [systems} theory]
(This is a light-hearted and ill-researched post. When the infinite amount of free time I ordered on Amazon finally arrives, I might dig into it deeply and be serious.) Everyone who tries to read widely about systemsy stuff will inevitably feel puzzled by the large-scale flow of ideas. In particular, there is a—sometimes crystal clear, […]
Some temporal network visualizations
I recently needed some colorful animations of temporal network data. You can see the result here. These film clips show the proximity of children in a French primary school (ages 6–12). Watch out for the clear transitions between lectures and recess or lunch break (e.g. around 3:28 min into the video below). A legend is […]
Systems diagrams and networks of climate change
Click here to get a PDF of our new review paper about the use of network methods in the climate sciences. It is co-authored by Juan Rocha of Stockholm Resilience Center and myself. Since almost a week it is on hold for moderation at arXiv for unknown reasons, in the meanwhile I’m happy to share […]
Calculating reachability in temporal networks
(Backward or forward) reachability in temporal networks is a measure of the position of nodes, akin to the centrality measures of static networks. The (forward, or downstream) reachability of a node i is the fraction of nodes that can be reached by time-respecting paths from i at time t, averaged over time from the beginning […]
Common mistakes in network code
This is not really a blog post, but rather a checklist of more or less painful mistakes in networks-science programs by me, or my students or teachers. (As a side note, computer scientists tend to be better a this, but are by no means immune to it.) This list is incomplete. I plan to fill […]
Petter Holme 