Edges in a Depth-First Spanning Tree Advancing edges:going from a node m to a proper descendant of m in the tree Retreating edges:going from a node m to an ancestor of m in the tree (possibly to m itself). Cross edges:edges m>n such that neither m nor n is an ancestor of the other in the DFST CS308 Compiler Theory 8Edges in a Depth-First Spanning Tree • Advancing edges: going from a node m to a proper descendant of m in t he tree • Retreating edges: going from a node m to an ancestor of m in the tree ( ibl t it lf) (possibly to m itself) . • C d ross e dges: e dges m Æ n such th t ith i t f h th a t neither m nor n is an ances tor o f the other in the DFST CS308 Compiler Theory 8