Graceful trees whose diameters are four
Lu Xue · Journal of Central China Normal University · 2000
Whether all trees whose diameters are four are graceful? Huang and many other scholars believe that this question is the key to the Guess of Graceful trees.This paper divides all the trees whose diameters are four into two classes and reduce the graceful quality of them to the graceful quality of dandelion which is definited in this paper It also gives the proof of the graceful quality of two kinds of dandelion .