семинар МОИ

На 31 октомври 2023 г. (вторник) от 16:00 часа в зала 578 на ИМИ-БАН ще се проведе заседание на семинара на секция „Математически основи на информатиката". Доклад ще изнесе д-р Константин Воробьов (ИМИ - БАН). Абстракт. In this work, we consider the problem of determining the exact value of A_2(n, {d, d+2}) defined as the maximal cardinality of a binary code of length n with two possible distances d and d+2. We prove that for fixed even d and n big enough, an optimal code must be a constant-weight code of weight d/2+1 with possibly no more than one additional codeword of a different weight. We also find exact values A_2(n, {4, 6}) and A_2(n, {6, 8}) starting from some n. This is a joint [...]

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 degree k. We will talk [...]