Editorial and community service

• Editorial board member: Mathematics (2021–2023); Astronomy (2021–present)
• Refereeing for Mathematical Reviews and journals in relativity/cosmology and dynamical systems (selected: PRD, CQG, GRG, EPJC, J. Geom. Phys.)

Research leadership

• Founder and Director, Laboratory of Geometry, Dynamical Systems and Cosmology (University of the Aegean; founded 1998)

Conference and school organization (selected)

• Chairs/rapporteur roles in the Marcel Grossmann meetings (selected years)
• Organization/co-organization of Aegean schools and related workshops (selected years)