BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Discrete Mathematics Group - ECPv6.15.20//NONSGML v1.0//EN
CALSCALE:GREGORIAN
METHOD:PUBLISH
X-ORIGINAL-URL:https://dimag.ibs.re.kr
X-WR-CALDESC:Events for Discrete Mathematics Group
REFRESH-INTERVAL;VALUE=DURATION:PT1H
X-Robots-Tag:noindex
X-PUBLISHED-TTL:PT1H
BEGIN:VTIMEZONE
TZID:Asia/Seoul
BEGIN:STANDARD
TZOFFSETFROM:+0900
TZOFFSETTO:+0900
TZNAME:KST
DTSTART:20220101T000000
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20230309T100000
DTEND;TZID=Asia/Seoul:20230309T110000
DTSTAMP:20260418T135834
CREATED:20230118T233622Z
LAST-MODIFIED:20240707T074003Z
UID:6685-1678356000-1678359600@dimag.ibs.re.kr
SUMMARY:Marcelo Sales\, On Pisier type problems
DESCRIPTION:A subset $A\subseteq \mathbb Z$ of integers is free if for every two distinct subsets $B\, B’\subseteq A$ we have \[ \sum_{b\in B}b\neq \sum_{b’\in B’} b’.\]Pisier asked if for every subset $A\subseteq \mathbb Z$ of integers the following two statement are equivalent: \n(i) $A$ is a union of finitely many free sets.\n(ii) There exists $\epsilon>0$ such that every finite subset $B\subseteq A$ contains a free subset $C\subseteq B$ with $|C|\geq \epsilon |B|$. \nIn a more general framework\, the Pisier question can be seen as the problem of determining if statements (i) and (ii) are equivalent for subsets of a given structure with prescribed property. We study the problem for several structures including $B_h$-sets\, arithmetic progressions\, independent sets in hypergraphs and configurations in the euclidean space. This is joint work with Jaroslav Nešetřil and Vojtech Rödl.
URL:https://dimag.ibs.re.kr/event/2023-03-09/
LOCATION:Zoom ID: 224 221 2686 (ibsecopro)
CATEGORIES:Virtual Discrete Math Colloquium
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20230316T100000
DTEND;TZID=Asia/Seoul:20230316T110000
DTSTAMP:20260418T135834
CREATED:20230213T121859Z
LAST-MODIFIED:20240707T073949Z
UID:6788-1678960800-1678964400@dimag.ibs.re.kr
SUMMARY:Paul Seymour\, A loglog step towards the Erdős-Hajnal conjecture
DESCRIPTION:In 1977\, Erdős and Hajnal made the conjecture that\, for every graph $H$\, there exists $c>0$ such that every $H$-free graph $G$ has a clique or stable set of size at least $|G|^c$; and they proved that this is true with $|G|^c$ replaced by $2^{c\sqrt{\log |G|}}$. \nThere has no improvement on this result (for general $H$) until now\, but now we have an improvement: that for every graph $H$\, there exists $c>0$ such that every $H$-free graph $G$ with $|G|\ge 2$ has a clique or stable set of size at least $$2^{c\sqrt{\log |G|\log\log|G|}}.$$ This talk will outline the proof. \nJoint work with Matija Bucić\, Tung Nguyen and Alex Scott.
URL:https://dimag.ibs.re.kr/event/2023-03-16/
LOCATION:Zoom ID: 869 4632 6610 (ibsdimag)
CATEGORIES:Virtual Discrete Math Colloquium
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20230322T163000
DTEND;TZID=Asia/Seoul:20230322T173000
DTSTAMP:20260418T135834
CREATED:20230118T233720Z
LAST-MODIFIED:20240707T092054Z
UID:6688-1679502600-1679506200@dimag.ibs.re.kr
SUMMARY:Qizhong Lin\, Two classical Ramsey-Turán numbers involving triangles
DESCRIPTION:In 1993\, Erdős\, Hajnal\, Simonovits\, Sós and Szemerédi proposed to determine the value of Ramsey-Turán density $\rho(3\,q)$ for $q\ge3$. Erdős et al. (1993) and Kim\, Kim and Liu (2019) proposed two corresponding conjectures. However\, we only know four values of this Ramsey-Turán density by Erdős et al. (1993). There is no progress on this classical Ramsey-Turán density since then. In this talk\, I will introduce two new values of this classical Ramsey-Turán density. Moreover\, the corresponding asymptotically extremal structures are weakly stable\, which answers a problem of Erdős et al. (1993) for the two cases. Joint work with Xinyu Hu.
URL:https://dimag.ibs.re.kr/event/2023-03-22/
LOCATION:Zoom ID: 224 221 2686 (ibsecopro)
CATEGORIES:Virtual Discrete Math Colloquium
END:VEVENT
END:VCALENDAR