»ã±¨±êÌâ (Title)£ºC_7µÄÆ½ÃæTuranÊý£¨Planar Turan number of C_7£©
»ã±¨ÈË (Speaker)£ºÓôÐÇÐÇ ½ÌÊÚ£¨ÃÀ¹ú×ôÖÎÑÇÀí¹¤Ñ§Ôº£©
»ã±¨¹¦·ò (Time)£º2023Äê5ÔÂ22ÈÕ(ÖÜÒ») 10:00
»ã±¨µØÖ· (Place)£ºÐ£±¾²¿F309
Ô¼ÇëÈË(Inviter)£ºÐ»ÆëÇß
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»ã±¨ÌáÒª£ºThe planar Turan number of a graph H is the maximum number of edge in an n-vertex graph without H as a subgraph. We show that this number for C_7, the 7-cycle, is at most 18n/7 - 48/7, for n > 38, which is best possible for infinitely many n.