uploaded minutes

Author: MartinHinz

content/minutes/2025-11-07

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+---
+title: "51th regular meeting"
+date: 2025-11-07
+---
+
+10 ppl attended
+
+## Invited presentation
+
+- Speaker: Emily Coco
+- Topic: Least-cost path analysis using agent-based modelling (ABM)
+
+Emily presented her work on modelling least-cost paths on the question of Neanderthal and Denisova mobility in the pleistocene landscapes using agent-based approaches. The model restricts visibility and forward movement — agents cannot move immediatly backwards — which results in a bounded rationality movement dynamics.
+
+Originally developed in NetLogo, the model was extremely computationally demanding: a single run took around 14 days and required approximately 70 GB of storage per iteration.
+Emily has since ported the model to Repast Symphony, which allows more efficient execution and better control over simulation parameters.
+
+Participants raised several questions concerning the implementation and conceptual framing. Reuse and Reproducability was another focus, NASSA was proposed as model library. 
+
+Emily also discussed her exploration of GPU computing, outlining current possibilities (switching to GPU and parallelisation) and open questions about how such acceleration could be effectively implemented in ABM frameworks.
+
+## Discussion highlights
+
+### Parallelisation and computational strategies
+- Participants exchanged ideas on the potential of parallelisation in ABM workflows.
+- Jim asked how Repast Symphony compares to “plain” Java implementations regarding scalability and transparency.
+- Not so many practical experiences seem to exist with parallelisation of ABMs, a potential aspect for further exploration 
+
+### Conceptual reflections on ABM
+- A short discussion arose as to whether ABM is the most appropriate tool for least-cost path problems and what might be the right analytical units.
+- Participants considered increasing model complexity by introducing a dynamic cost surface, accounting for changing temporal and Predator-Prey dynamics.
+
+## Other CAA related activities:
+- Two workshops affiliated with the SSLA will take place at CAA 2026 in Vienna:
+  - Matteo (Code Review)
+	- Petr (Intro to R) 
+
+## Decisions and actions
+- Maintain-a-thon initiative (Zack Batist):
+- Agreed to launch a “maintain-a-thon” in January 2026, where members revisit older codebases, ensure they still run, document them properly, and deposit them in long-term repositories.
+- The initiative will be hosted via the SSLA website, accompanied by social media outreach.
+
+## Conclusions
+- The maintain-a-thon was endorsed as a community activity promoting sustainability and transparency (January 2026).
+- GPU acceleration and parallelisation remain promising but complex paths for ABMs.
+- ABM continues to raise conceptual as well as technical questions about appropriate modelling scales and interpretability.
+- Sharing and refactoring experiences across platforms can strengthen collective learning within the community.
+
+Next SIG Meeting: December 2026, concrete date depending on the when2meet result (https://www.when2meet.com/?33002028-2srLL, details to be announced via mailing list)