BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Institute of Mathematics and Informatics - ECPv6.0.8//NONSGML v1.0//EN
CALSCALE:GREGORIAN
METHOD:PUBLISH
X-WR-CALNAME:Institute of Mathematics and Informatics
X-ORIGINAL-URL:https://math.bas.bg
X-WR-CALDESC:Събития за Institute of Mathematics and Informatics
REFRESH-INTERVAL;VALUE=DURATION:PT1H
X-Robots-Tag:noindex
X-PUBLISHED-TTL:PT1H
BEGIN:VTIMEZONE
TZID:Europe/Sofia
BEGIN:DAYLIGHT
TZOFFSETFROM:+0200
TZOFFSETTO:+0300
TZNAME:EEST
DTSTART:20250330T010000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:+0300
TZOFFSETTO:+0200
TZNAME:EET
DTSTART:20251026T010000
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
DTSTART;TZID=Europe/Sofia:20250507T160000
DTEND;TZID=Europe/Sofia:20250507T173000
DTSTAMP:20260418T055746
CREATED:20250505T165639Z
LAST-MODIFIED:20250505T170018Z
UID:17708-1746633600-1746639000@math.bas.bg
SUMMARY:Семинар по геометрия на МЦМН
DESCRIPTION:Следващата сбирка на Семинара по геометрия на МЦМН\nще се проведе в сряда\, 7 май 2025 г. от 16:00 ч. в зала 403 и онлайн в Zoom: \nДоклад на тема \nBinary Quadratic Forms and Conway’s Topographs (Lecture 2 of 3)\n\nще изнесе Nikita Kalinin\, Guangdong Technion Israel Institute of Technology. \n\nСледващата лекция ще бъде на 14.05.2025 от 16:00 ч.\n\nAbstract: Binary quadratic forms are as elementary as they are mysterious—much like prime numbers. In 1997\, John Conway introduced topographs\, a powerful geometric tool that provides a geometric visualization of binary quadratic forms and their values. These lectures will explore how topographs\, combined with telescoping summation techniques\, yield elegant formulas — some with intuitive geometric interpretations. For instance\, consider the following result: \nLet \n\(A = \big\{ (x\, y) \mid  x\,y\in \mathbb{Z}_{\geq 0}^2\, \det(x \ \ y) = 1 \big\}\,\) \nthe set of pairs of lattice vectors in the first quadrant spanning a parallelogram of oriented area 1. Then\, \n\(4 \displaystyle\sum_{(x\,y) \in A} \frac{1}{|x|^2 \cdot |y|^2 \cdot |x+y|^2} = \pi.\) \nLecture Outline \n1. Introduction to Binary Quadratic Forms and Conway’s Topographs\nWe will begin with the basics of binary quadratic forms and their classification\, followed by an introduction to Conway’s topographs—a visual and geometric framework for understanding them. \n2. Class Number Formula and Summation over Topographs\nBuilding on the first lecture\, we will explore the class number formula and how summation identities arise naturally from the structure of topographs. \n3. Evaluation of Lattice Sums via Telescoping over Topographs\nThe final lecture will focus on telescoping techniques\, demonstrating how they can be used to evaluate intricate lattice sums—such as the one above—with geometric meaning. \n\n\nZoom link:\nhttps://us02web.zoom.us/j/86186281353?pwd=6CARUygJaA3HiTNAt3norZQRFt8fIL.1\n\nВидеозапис и презентация на първата лекция:\n\nhttps://youtu.be/z7Pz33JyCuA?si=rQ2L4yXJHMdiDkpe\nhttps://kilin-math.github.io/assets/numbers/telescopic_presentation1.pdf
URL:https://math.bas.bg/event/copy-%d1%81%d0%b5%d0%bc%d0%b8%d0%bd%d0%b0%d1%80-%d0%bf%d0%be-%d0%b3%d0%b5%d0%be%d0%bc%d0%b5%d1%82%d1%80%d0%b8%d1%8f-%d0%bd%d0%b0-%d0%bc%d1%86%d0%bc%d0%bd-3/
LOCATION:Институт по математика и информатика – БАН\, Block 8\, 1113 БАН IV км.\, София\, Bulgaria
CATEGORIES:Редовен семинар
ORGANIZER;CN="%D0%98%D0%BD%D1%81%D1%82%D0%B8%D1%82%D1%83%D1%82%20%D0%BF%D0%BE%20%D0%BC%D0%B0%D1%82%D0%B5%D0%BC%D0%B0%D1%82%D0%B8%D0%BA%D0%B0%20%D0%B8%20%D0%B8%D0%BD%D1%84%D0%BE%D1%80%D0%BC%D0%B0%D1%82%D0%B8%D0%BA%D0%B0%20-%20%D0%91%D0%90%D0%9D":MAILTO:office@math.bas.bg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Sofia:20250513T140000
DTEND;TZID=Europe/Sofia:20250513T151500
DTSTAMP:20260418T055746
CREATED:20250512T114627Z
LAST-MODIFIED:20250512T115322Z
UID:17734-1747144800-1747149300@math.bas.bg
SUMMARY:Семинар на МЦМН
DESCRIPTION:Сбирка на семинара на МЦМН ще се проведе на 13.05.2025 г. (вторник) от 14:00 ч. в зала 403 на ИМИ – БАН. \nДокладчик: Milan Zlatanovic (University of Niš) \nДоклад: Non-symmetric gravitational theorys \nРезюме: We will consider a connection with totally skew-symmetric torsion on non-symmetric (semi-) Riemann manifolds that satisfy Einstein’s metric condition (EMC). We proved that an almost Hermitian manifold is a non-symmetric Riemann manifold that satisfies EMC if and only if it is a Nearly Kahler manifold. We will also show what happens in the case of para Hermitian manifold\, contact\, and para-contact manifolds that satisfy EMC. We show that a connection with skew symmetric torsion satisfying EMC exists on an almost contact metric manifolds when it is D-homothetic to a cosymplectic manifold. We proved the structure theorem for the new class of almost contact metric manifold and special attention we have focused on dimension 5. As a natural continuation of this research\, we dealt with the case of Lorentzian manifolds. \nThis is joint work with Stefan Ivanov and Nikola Stanchev.\nДопълнителна информация: https://icms.bg/category/icms-seminar/ \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-%d0%bc%d1%86%d0%bc%d0%bd-31/
LOCATION:Институт по математика и информатика – БАН\, Block 8\, 1113 БАН IV км.\, София\, Bulgaria
CATEGORIES:Редовен семинар
END:VEVENT
END:VCALENDAR