王力工 教授学术报告
Title: Spectral radius conditions for the existence of a larger class of spiders and all trees of diameter at most four
Speaker: Prof. Ligong WANG （王力工）
Affiliation: Northwestern Polytechnical University（西北工业大学）
Time: 16:00, Friday, November 18th, 2022 （UTC+8, Beijing Time）
Venue: 腾讯会议/VooV Meeting（392-398-926）
入会链接：https://meeting.tencent.com/dm/dexuAisWJHNp
Inviter: Shuliang BAI（白淑亮）
Abstract
Let µ(G) denote the spectral radius of a graph G. Let Bs,t denote a broom on s+t vertices obtained by identifying the center of a star K1,s and an end-vertex of a path Pt. Let S(k+1)·2 = S2,...,2 denote the tree obtained a star on k + 2 vertices by subdividing each of its k + 1 edges once. We partly confirm a Brualdi-Solheid-Turán type conjecture due to Nikiforov, which is a spectral radius analogue of the well-known Erdős-Sós Conjecture that any tree of order t is contained in a graph of average degree greater than t − 2. We confifirm Nikiforov’s Conjecture for a larger class of spiders, all brooms, or for all trees of diameter at most four expect the tree S(k+1)·2. For our proofs we also obtain a new Turán type result which might turn out to be of independent interest. This is a joint work with Xiangxiang Liu and Hajo Broersma.
About the Speaker
王力工，西北工业大学教授、博士生导师，荷兰Twente大学博士，研究方向为图论及其应用。主持国家自然基金、省、部级基金5项，作为主要成员参加国家自然科学基金5项和陕西省自然科学基金1项。现为美国《数学评论》的评论员，在《Linear Algebra and its Applications》、《Discrete Mathematics》、《Discrete Applied Mathematics》、《Electronic Journal of Combinatorics》等国内外学术期刊发表SCI论文100余篇。指导博士生4人获国家自然基金委资助出国留学。是国家级精品课程《数学建模》课程和国家级教学成果一等奖的主要参加者。是西北工业大学数学建模总教练，多次指导大学生和研究生参加国际、全国数学建模竞赛，获国际特等奖1项、国际一等奖6项、全国一等奖6项。曾被评为陕西省数学建模优秀指导教师和陕西省数学建模优秀组织工作者。曾被评为西北工业大学本科最满意教师。