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DTSTART:20250101T000000
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DTSTART;TZID=UTC:20250122T153000
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CREATED:20250118T104832Z
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UID:7875-1737559800-1737563400@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Ramsey numbers of signed graphs\nBen Seamone\, Dawson College and Université de Montréal\n\nAbstract:\nNathan Acheampong (Université de Montréal) Francis Clavette (Université de Montréal)\nGeˇna Hahn (Université de Montréal) Margaux Marseloo (Université Paris-Saclay) Viktor\nPaardekooper (Université de Montréal)\, and Ben Seamone* (Dawson College & Université de Montréal)\n\nA signed graph is a pair (G\, σ) where G = (V\,E) is a graph and σ : E(G) → {+\, −} is\na signature which assigns a sign to each edge of G. One well-studied operation on signed\ngraphs is that of switching at a vertex v ∈ V (G)\, by which we mean that every edge incident\nto v has its sign changed. Two signed graphs are called equivalent if one can be obtained\nfrom the other by a sequence of vertex switches.\n\nWe call a complete signed graph positive (negative) if every edge is positive (negative). We\nstudy the following Ramsey problem on signed graphs – for positive integers s and t\, what\nis the smallest n such that every signed complete graph on n vertices has an equivalent\nsigned complete graph containing either a negative Ks or positive Kt? This “signed Ramsey\nnumber” is denoted r±(s\, t). We show how a variety of approaches lead to upper and lower\nbounds on r±(s\, t)\, settle an open problem by establishing the exact value of r±(4\, t) for\nevery t\, and determine the asymptotics of r±(5\, t) and r±(6\, t).\n \nZoom link:\nhttps://us02web.zoom.us/j/86861499971?pwd=rTDAaju0TCu24asnaBGvkuNlT11KZ1.1\n\nMeeting ID: 868 6149 9971\nPasscode: 325258
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-23/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette%20Janssen":MAILTO:jeannette.janssen@dal.ca
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