salespurchasingand manufacturing the internal nodes store salesinternationaloverseaselectronics 'usand manufacturing formal tree definition formallywe define tree as set of nodes storing elements such that the nodes have parent-child relationshipthat satisfies the following propertiesif is nonemptyit has special nodecalled the root of tthat has no parent each node of different from the root has unique parent node wevery node with parent is child of note that according to our definitiona tree can be emptymeaning that it doesn' have any nodes this convention also allows us to define tree recursivelysuch that tree is either empty or consists of node rcalled the root of tand (possibly emptyset of trees whose roots are the children of other node relationships