BEGIN:VCALENDAR VERSION:2.0 PRODID:-//132.216.98.100//NONSGML kigkonsult.se iCalcreator 2.20.4// BEGIN:VEVENT UID:20250918T082758EDT-5468xt57aI@132.216.98.100 DTSTAMP:20250918T122758Z DESCRIPTION:Title: Measurable solutions to abstract systems of congruence. \n\nAbstract: An abstract system of congruences describes a way of partiti oning a space into finitely many pieces satisfying certain congruence rela tions. Examples of abstract systems of congruences include paradoxical dec ompositions and partitioning a set into n congruent pieces. We consider th e general question of when there are realizations of abstract systems of c ongruences satisfying various measurability constraints. We completely cha racterize which abstract systems of congruences can be realized by nonmeag er Baire measurable pieces of the sphere under the action of rotations on the 2-sphere. We also construct Borel realizations of abstract systems of congruences for the action of PSL2(Z) on the projective line. The combinat orial underpinnings of our proof are certain types of decomposition of Bor el graphs into paths\n DTSTART:20190321T183000Z DTEND:20190321T193000Z LOCATION:Room 920\, Burnside Hall\, CA\, QC\, Montreal\, H3A 0B9\, 805 rue Sherbrooke Ouest SUMMARY:Andrew Marks (UCLA) URL:/mathstat/channels/event/andrew-marks-ucla-295465 END:VEVENT END:VCALENDAR