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DTSTART;TZID=Europe/Sofia:20240208T150000
DTEND;TZID=Europe/Sofia:20240208T163000
DTSTAMP:20260601T133221
CREATED:20240205T104414Z
LAST-MODIFIED:20240206T152142Z
UID:15904-1707404400-1707409800@math.bas.bg
SUMMARY:Семинар на секция "Математически основи на информатиката"
DESCRIPTION:На 8 февруари 2024 г. (четвъртък) от 15:00 часа в зала 256 на ИМИ-БАН\nще се проведе заседание на семинара на секция\n„Математически основи на информатиката”. \nДоклад на тема \n Extremal problems in Euclidean combinatorial geometry\nще изнесе доц. д-р Данила Черкашин \nАбстракт.  I will talk about several problems in the intersection of extremal combinatorics and Euclidean geometry. Recent results on the Steiner tree problem\, Gilbert-Steiner problem\, and Nelson-Hadwiger problem will be presented. \nСеминарът може да бъде проследен и на https://meet.jit.si/IMI-MOI-14400
URL:https://math.bas.bg/event/%d1%81%d0%b5%d0%bc%d0%b8%d0%bd%d0%b0%d1%80-%d0%bd%d0%b0-%d1%81%d0%b5%d0%ba%d1%86%d0%b8%d1%8f-%d0%bc%d0%b0%d1%82%d0%b5%d0%bc%d0%b0%d1%82%d0%b8%d1%87%d0%b5%d1%81%d0%ba%d0%b8-%d0%be%d1%81%d0%bd%d0%be-21/
LOCATION:Институт по математика и информатика – БАН\, Block 8\, 1113 БАН IV км.\, София\, Bulgaria
CATEGORIES:Редовен семинар
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Sofia:20231110T140000
DTEND;TZID=Europe/Sofia:20231110T153000
DTSTAMP:20260601T133221
CREATED:20231106T143730Z
LAST-MODIFIED:20231106T144427Z
UID:15357-1699624800-1699630200@math.bas.bg
SUMMARY:Семинар на секция "Математически основи на информатиката"
DESCRIPTION:На 10 ноември 2023 г. (вторник) от 14:00 часа в зала 478 на ИМИ-БАН\nще се проведе заседание на семинара на секция\n„Математически основи на информатиката”. \nДоклад на тема \nOn induced \(C_4\)-free graphs with high average degree\nще изнесе Антонио Жирао. \nАбстракт.  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 \(k\). \nWe will talk about a recent result which strengthens this result of Kühn and Osthus in two ways. First\, we prove an analogous induced version and secondly we give much better bounds for the function f allowing us obtain few non-trivial results as simple corollaries. Finally\, we use these methods to confirm a conjecture Bonamy et al.\nАнтонио Жирао e пост-докторант в Оксфордския Университет под ръководството на проф. Алекс Скот. Преди да заеме тази позиция\, Антонио работи като пост-докторант в Хайделбергския Университет под ръководството на проф. Феликс Йоос и в Университета в Бирмингам под ръководството на проф. Даниела Кюн и проф. Дерек Остюс. Защитава докторантурата в Университета в Кеймбридж под ръководството на проф. Бела Болобаш през 2018 г.
URL:https://math.bas.bg/event/%d1%81%d0%b5%d0%bc%d0%b8%d0%bd%d0%b0%d1%80-%d0%bd%d0%b0-%d1%81%d0%b5%d0%ba%d1%86%d0%b8%d1%8f-%d0%bc%d0%b0%d1%82%d0%b5%d0%bc%d0%b0%d1%82%d0%b8%d1%87%d0%b5%d1%81%d0%ba%d0%b8-%d0%be%d1%81%d0%bd%d0%be-20/
LOCATION:Институт по математика и информатика – БАН\, Block 8\, 1113 БАН IV км.\, София\, Bulgaria
CATEGORIES:Редовен семинар
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Sofia:20231031T160000
DTEND;TZID=Europe/Sofia:20231031T173000
DTSTAMP:20260601T133221
CREATED:20231026T165751Z
LAST-MODIFIED:20231026T165751Z
UID:15291-1698768000-1698773400@math.bas.bg
SUMMARY:Семинар на секция "Математически основи на информатиката"
DESCRIPTION:На 31 октомври 2023 г. (вторник) от 16:00 часа в зала 578 на ИМИ-БАН\nще се проведе заседание на семинара на секция\n„Математически основи на информатиката”. \nДоклад ще изнесе д-р Константин Воробьов (ИМИ – БАН). \nАбстракт. 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.\nWe also find exact values \(A_2(n\, {4\, 6})\) and \(A_2(n\, {6\, 8})\) starting from some \(n\). \nThis is a joint work with Ivan Landjev. \n 
URL:https://math.bas.bg/event/%d1%81%d0%b5%d0%bc%d0%b8%d0%bd%d0%b0%d1%80-%d0%bd%d0%b0-%d1%81%d0%b5%d0%ba%d1%86%d0%b8%d1%8f-%d0%bc%d0%b0%d1%82%d0%b5%d0%bc%d0%b0%d1%82%d0%b8%d1%87%d0%b5%d1%81%d0%ba%d0%b8-%d0%be%d1%81%d0%bd%d0%be-19/
LOCATION:Институт по математика и информатика – БАН\, Block 8\, 1113 БАН IV км.\, София\, Bulgaria
CATEGORIES:Редовен семинар
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Sofia:20230822T160000
DTEND;TZID=Europe/Sofia:20230822T173000
DTSTAMP:20260601T133221
CREATED:20230821T171909Z
LAST-MODIFIED:20230821T171909Z
UID:14881-1692720000-1692725400@math.bas.bg
SUMMARY:Семинар на секция "Математически основи на информатиката"
DESCRIPTION:На 22 август 2023 г. (вторник) от 16:00 часа в зала 503 на ИМИ-БАН\nще се проведе заседание на семинара на секция\n„Математически основи на информатиката”. \nДоклад на тема: \nData Attribution: Scaling up and Applications to Defending Against Backdoor Attacks\nще изнесе\nКристиян Георгиев\, докторант в MIT под ръководството на Александър Мондри.\nАбстракт. The goal of data attribution is to trace model predictions back to training data. Despite a long line of work towards this goal\, existing approaches to data attribution tend to force users to choose between computational tractability and efficacy. That is\, computationally tractable methods can struggle with accurately attributing model predictions in non-convex settings (e.g.\, in the context of deep neural networks)\, while methods that are effective in such regimes require training thousands of models\, which makes them impractical for large models or datasets. \nIn this talk\, I will first introduce TRAK (Tracing with the Randomly-projected After Kernel)\, a data attribution method that is both effective and computationally tractable for large-scale\, differentiable models. Next\, I will showcase how to leverage data attribution methods for building defenses against backdoor attacks. In a backdoor attack\, an adversary inserts maliciously constructed backdoor examples into a training set to make the resulting model vulnerable to manipulation. I will show that without structural information about the training data distribution\, backdoor attacks are indistinguishable from naturally-occurring features in the data–and thus impossible to “detect” in a general sense. With this insight in mind\, I will describe how we use TRAK (and other data attribution methods) towards finding features corresponding to the “backdoored” samples.
URL:https://math.bas.bg/event/%d1%81%d0%b5%d0%bc%d0%b8%d0%bd%d0%b0%d1%80-%d0%bd%d0%b0-%d1%81%d0%b5%d0%ba%d1%86%d0%b8%d1%8f-%d0%bc%d0%b0%d1%82%d0%b5%d0%bc%d0%b0%d1%82%d0%b8%d1%87%d0%b5%d1%81%d0%ba%d0%b8-%d0%be%d1%81%d0%bd%d0%be-18/
LOCATION:Институт по математика и информатика – БАН\, Block 8\, 1113 БАН IV км.\, София\, Bulgaria
CATEGORIES:Редовен семинар
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Sofia:20230627T140000
DTEND;TZID=Europe/Sofia:20230627T153000
DTSTAMP:20260601T133221
CREATED:20230623T104309Z
LAST-MODIFIED:20230623T104309Z
UID:14613-1687874400-1687879800@math.bas.bg
SUMMARY:Семинар на секция "Математически основи на информатиката"
DESCRIPTION:На 27 юни 2023 г. (вторник) от 14:00 часа\nв зала 278 на ИМИ-БАН\nще се проведе заседание на семинара на секция\n„Математически основи на информатиката”. Доклад на тема:\n\nThe Erdős Box Problem and the Combinatorial Nullstellensatz\n\nще изнесе\nд-р Алексей Гордеев\, гостуващ учен към секцията.\n\n\nАбстракт. The Erdős box problem can be formulated as follows: how many points of {1\,2\,…\,n}^m can we take so that for every m-dimensional box (hyperrectangle with sides parallel to coordinate axes) at least one of its vertices is not taken? When m is fixed and n increases\, an order of growth of this number is known only in the case m=2. \nI will talk about Alon’s Combinatorial Nullstellensatz and its connection with the Erdős box problem and\, more generally\, with hypergraph Turán numbers. In particular\, I will show how a certain generalization of Combinatorial Nullstellensatz can be used to obtain explicit examples for the Erdős box problem\, asymptotically matching best known examples when m<5.
URL:https://math.bas.bg/event/%d1%81%d0%b5%d0%bc%d0%b8%d0%bd%d0%b0%d1%80-%d0%bd%d0%b0-%d1%81%d0%b5%d0%ba%d1%86%d0%b8%d1%8f-%d0%bc%d0%b0%d1%82%d0%b5%d0%bc%d0%b0%d1%82%d0%b8%d1%87%d0%b5%d1%81%d0%ba%d0%b8-%d0%be%d1%81%d0%bd%d0%be-17/
LOCATION:Институт по математика и информатика – БАН\, Block 8\, 1113 БАН IV км.\, София\, Bulgaria
CATEGORIES:Редовен семинар
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Sofia:20230510T150000
DTEND;TZID=Europe/Sofia:20230510T160000
DTSTAMP:20260601T133221
CREATED:20230405T090645Z
LAST-MODIFIED:20230405T090909Z
UID:14180-1683730800-1683734400@math.bas.bg
SUMMARY:Семинар на секция "Математически основи на информатиката"
DESCRIPTION:На 10 май 2023 г. (сряда) от 15:00 часа\nв зала 503 на ИМИ-БАН\nще се проведе заседание на семинара на секция\n„Математически основи на информатиката”. Доклад на тема:\n\nTernary self-dual codes\, Hadamard matrices and related designs\n\nще изнесе\nпроф. Владимир Тончев\,\nMichigan Technological University\, Houghton\, USA.\n\n\nАбстракт на доклада може да изтеглите тук.
URL:https://math.bas.bg/event/%d1%81%d0%b5%d0%bc%d0%b8%d0%bd%d0%b0%d1%80-%d0%bd%d0%b0-%d1%81%d0%b5%d0%ba%d1%86%d0%b8%d1%8f-%d0%bc%d0%b0%d1%82%d0%b5%d0%bc%d0%b0%d1%82%d0%b8%d1%87%d0%b5%d1%81%d0%ba%d0%b8-%d0%be%d1%81%d0%bd%d0%be-16/
LOCATION:Институт по математика и информатика – БАН\, Block 8\, 1113 БАН IV км.\, София\, Bulgaria
CATEGORIES:Редовен семинар
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Sofia:20230309T150000
DTEND;TZID=Europe/Sofia:20230309T160000
DTSTAMP:20260601T133221
CREATED:20230307T214102Z
LAST-MODIFIED:20230307T214128Z
UID:13967-1678374000-1678377600@math.bas.bg
SUMMARY:Семинар на секция "Математически основи на информатиката"
DESCRIPTION:На 9 март 2023 г. (четвъртък) от 15:00 часа в зала 503 на ИМИ-БАН\nще се проведе заседание на семинара на секция „Математически основи на информатиката”. Доклад на тема:\n\nIntroduction to the dimer model on the plane: scaling limit and conformal invariance\n\nще изнесе\nд-р Михаил Басок\, гостуващ учен по програма ПИКОМ.\n\nАбстракт:  Dimer model is a classical model in planar statistical physics. Given a finite graph\, the model is described as a probability distribution on the set of dimer covers (=perfect matchings) of the graph. In the case when the graph is planar each dimer cover is described with the so-called height function\, which is a certain function on the faces of the graph.\n\nIn this talk we consider a particular setup when the graph is given as a subgraph of a square lattice on the plane and the distribution on the space of dimer covers is uniform. Given a simply-connected domain we consider a sequence of such graphs approximating this domain as the step of the lattice tends to zero and sample the dimer model on each of the graphs. Classical theorem of Kenyon asserts that under a certain local combinatorial conditions the sequence of the corresponding (random) height functions has a conformally invariant limit. Moreover\, this limit is proven to be the Gaussian free field with Dirichlet boundary conditions in the initial domain. \nWe will discuss heuristics behind this theorem and the approтach to proving it via discrete complex analysis developed by Kenyon. If time permits\, we will also discuss random loop ensembles arising from a pair of two independent dimer covers and its convergence to a conformally invariant limit proved in our joint work with Dmitry Chelkak.
URL:https://math.bas.bg/event/copy-%d1%81%d0%b5%d0%bc%d0%b8%d0%bd%d0%b0%d1%80-%d0%bd%d0%b0-%d1%81%d0%b5%d0%ba%d1%86%d0%b8%d1%8f-%d0%bc%d0%b0%d1%82%d0%b5%d0%bc%d0%b0%d1%82%d0%b8%d1%87%d0%b5%d1%81%d0%ba%d0%b8-%d0%be%d1%81%d0%bd/
LOCATION:Институт по математика и информатика – БАН\, Block 8\, 1113 БАН IV км.\, София\, Bulgaria
CATEGORIES:Редовен семинар
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Sofia:20220705T140000
DTEND;TZID=Europe/Sofia:20220705T153000
DTSTAMP:20260601T133221
CREATED:20220701T092523Z
LAST-MODIFIED:20220701T092624Z
UID:12591-1657029600-1657035000@math.bas.bg
SUMMARY:Семинар "Математически основи на информатиката"\, доклад на Александър Барг
DESCRIPTION:На 05.07.2022г. oт 14:00 в заседателната зала на ИМИ-БАН\nще се състои сбирка на семинара на секция „Математически основи на информатиката“.\nДокладчик ще бъде проф. Александър Барг от Университета на Мериленд.\nТой ще изнесе доклад на тема \nRemarks on the 1st linear programming bound for binary codes\nAbstract: The “linear programming bound” on the rate of binary codes (1977) is a fundamental result in coding theory that continues to attract attention to this day\, with new proofs appearing every now and then. I will discuss 2 proofs from about 2006-08\, appearing in arXiv:cs/0512025 (Barg-Nogin) and arXiv:math/0702425 (Navon and Samorodnitsky). Both proofs are based on Fourier analytic arguments on the Boolean cube and exhibit interesting parallels and differences (none of them actually uses linear programming). One of the applications enables us to establish upper bounds on the maximum size of binary codes of large distance\, d=n/2 – t√n. \nПоканват се всички желаещи.
URL:https://math.bas.bg/event/%d1%81%d0%b5%d0%bc%d0%b8%d0%bd%d0%b0%d1%80-%d0%bc%d0%b0%d1%82%d0%b5%d0%bc%d0%b0%d1%82%d0%b8%d1%87%d0%b5%d1%81%d0%ba%d0%b8-%d0%be%d1%81%d0%bd%d0%be%d0%b2%d0%b8-%d0%bd%d0%b0-%d0%b8%d0%bd%d1%84%d0%be/
LOCATION:Институт по математика и информатика – БАН\, Block 8\, 1113 БАН IV км.\, София\, Bulgaria
CATEGORIES:Редовен семинар
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