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)