На 10 ноември 2023 г. (петък) от 13:00 часа ще се проведе хибридно заседание (присъствено в зала 578 на ИМИ-БАН и онлайн чрез платформата zoom) на семинара по „Алгебра и логика”. Доклад на тема: Transfinite version of the Mittag-Leffler condition for the vanishing of the derived limit ще изнесе Mishel Carelli (Technion – Israel Institute of Technology, Israel). Абстракт. We give a necessary and sufficient condition for an inverse sequence  S0 ← S1 ← . . . indexed by natural numbers to have lim¹S = 0. This condition can be treated as a transfinite version of the Mittag-Leffler condition. We consider inverse sequences in the category of abelian groups. We also show that the class of inverse sequences S such that lim S = lim¹S = [...]

На 10 ноември 2023 г. (вторник) от 14:00 часа в зала 478 на ИМИ-БАН ще се проведе заседание на семинара на секция „Математически основи на информатиката". Доклад на тема On induced C_4 -free graphs with high average degree ще изнесе Антонио Жирао. Абстракт.  A long-standing conjecture of Thomassen from the 80's states that every graph with sufficiently high average degree contains a subgraph with high girth and still preserving large enough average degree. This conjecture has only been resolved in the early 2000's by Kühn and Osthus in the first non-trivial case i.e. they showed that for every k , there is f(k) such the every graph with average degree at least f(k) contains a subgraph which is C_4 -free with average [...]