七点的Ｈｅｉｌｂｒｏｎ问题的证明熊斌（华东师大数学系）田廷彦（上海交大应用数学系）平面上的Ｈｅｉｌｂｒｏｎ问题是这样的：在平面上任给ｎ个点，每两点之间有一个距离，最大距离与最小距离之比记为λｎ，求人的最小值（即ｉｎｆλｎ）．已知ｉｎｆλ３＝１，ｉｎｆ... Proof of the Heilbron problem at seven points Xiong Bin (Department of Mathematics, East China Normal University) Tian Tingyan (Department of Applied Mathematics, Shanghai Jiaotong University) The Heilbron problem on the plane is such that there are n points in the plane, and there is a distance between each two points. The ratio of the maximum distance to the minimum distance is denoted as λn, and the minimum value for human being (ie, infλn). Known infλ3=1,inf...