This is the second call for participation for the *2nd SIGIR 2025 Workshop on Simulations for Information Access (Sim4IA)*.

The workshop will be held with SIGIR 2025 in Padua, Italy. It will provide a unique platform for researchers and practitioners to explore and discuss advancements in simulations for information access systems.

## tl;dr ---------- - 17 July 2025, co-located with SIGIR 2025 in Padua, Italy - Micro shared task data and framework available - Tech and infrastructure talks/presentations welcome - Keynote by Christine Bauer confirmed - We are on the ACM Slack: https://acmsigir.slack.com/archives/C08STM45N90 - Website: https://sim4ia.org/sigir2025/

## Micro Shared Task Data and Framework Available ----------------------------------------------------------------------- To drive a more focused discussion at the workshop, we designed a micro shared task that demonstrates how a shared task in user simulations might look. On 16 May 2025, we released the first training data set as well as a prebundled and dockerized version of SimIIR to give everyone a head start on the shared task.

Our shared task concept is based on the fundamental design principle of validating user simulations instead of measuring system effectiveness. We envision users interacting with a particular IA system, such as a traditional search engine (Task A) or a conversational system (Task B). We challenge participants to design and implement user simulators that can mimic the interactions of real users with these systems with a high degree of fidelity. The workshop features a stripped-down version of this concept, a micro shared task.

We will discuss the submissions and ideas for the next steps or evaluation measures at the workshop. Non-binding expression of interest to take part in the micro shared tasks: https://forms.gle/ftV8cwjywHWsBhCw9

More information on the shared task, data sets, and framework: https://sim4ia.org/sigir2025/#micro-shared-task

## Keynote by Christine Bauer ----------------------------------------- We are happy to announce that Christine Bauer has confirmed to give a keynote on “From toy models to tactics: What user simulation is good for”.

Christine Bauer is a Professor of Interactive Intelligent Systems at the Department of Artificial Intelligence and Human Interfaces (AIHI) at the University of Salzburg. She is involved in the EXDIGIT initiative, emphasizing interdisciplinary technologies in digital sciences. Her research lies at the intersection of human-centered computing, data science, and artificial intelligence, with a focus on context-aware recommender systems, particularly in the music and media domains. Her core interests include fairness and multi-method evaluation. Her multidisciplinary background drives her research activities.

More information on the keynote: https://sim4ia.org/sigir2025/#keynote

## Invitation of Tech/Infrastructure Talks ----------------------------------------------------- We reserved a special time slot at the workshop for talks on recent technologies and/or infrastructures for (user) simulations, and invite you to submit your ideas for such talks at the workshop.

Send a short email with your idea in the form of a title and roughly half a page of abstract to sigir2025@sim4ia.org

Check out the tentative program, shared task data and description, the keynote announcement, and much more at https://sim4ia.org/sigir2025/

See you in Padua!

Sim4IA Organizers Philipp Schaer, Christin Kreutz, Krisztian Balog, Timo Breuer, and Andreas Kruff