應學院邀請,蘭州大學張和平教授将在線作學術報告。
報告題目:柱形與環面格子圖的共振圖與匹配強迫譜
報告摘要:In a region R consisting of unit squares, a domino is the union of two adjacent squares and a (domino) tiling is a collection of dominoes with disjoint interior whose union is the region. The flip graph T(R) is defined on the set of all tilings of R such that two tilings are adjacent if we change one to another by a flip (a 90o rotation of a pair of side-by-side dominoes). It is well-known that T(R) is connected when R is simply connected. By using graph theoretical approach, we show that the flip graph of (2n+1)×2m quadriculated cylinder is still connected, but the flip graph of (2n+1)×2m quadriculated torus is disconnected and consists of exactly two isomorphic components.
For a tiling t, we associate an integer f(t), forcing number, as the minimum number of dominoes in t that is contained in no other tilings. As an application, we obtain that the forcing numbers of all tilings in (2n+1)×2m quadriculated cylinder and torus form respectively an integer interval whose maximum value is (n+1)m.
報告時間:2022年12月1日9:00
報告地點:騰訊會議:422-792-025
邀 請 人:姚海元副教授
屆時歡迎廣大師生參與交流!
報告人簡介
張和平,蘭州大學77779193永利教授(二級)、博士生導師,校學術委員會委員,院學術委員會主任。1994年獲四川大學博士學位,1999年晉升教授,2001年任博士生導師,2001年獲教育部“第三屆高校青年教師獎”,2002年獲國務院頒發的政府特殊津貼,2009年入選甘肅省領軍人才(2層次),2014年6月當選國際數學化學科學院院士。現任中國組合數學與圖論學會常務理事,中國運籌學會組合數學與圖論分會常務理事。主要從事圖的匹配理論、化學圖論和計算機網絡的研究,發表了180餘篇SCI 收錄學術論文,主持了國家自然科學基金項目7項,包括重點項目“應用圖論”。曾在香港浸會大學、法國巴黎南大學、澳大利亞Newcastle大學、美國中田納西州立大學、台灣中研院數學所學術訪問。