trees figure avl property destroyed by insertion of then fixed by single rotation figure single rotation fixes case property is violated at the root we perform single rotation between the root and its left child to fix the problem here are the before and after trees before after dashed line joins the two nodes that are the subject of the rotation next we insert which causes no problemsbut the insertion of creates violation at node that is fixed by single rotation besides the local change caused by the rotationthe programmer must remember that the rest of the tree has to be informed of this change here this means that ' right child must be reset to link to instead of forgetting to do so is easy and would destroy the tree ( would be inaccessible