theorem Th42: :: GLIB_008:42

for G2 being _Graph
for v1, v2 being Vertex of G2
for e being object
for G1 being addEdge of G2,v1,e,v2
for w1 being Vertex of G1 st not e in the_Edges_of G2 & w1 = v1 holds
G1 .reachableFrom w1 = (G2 .reachableFrom v1) \/ (G2 .reachableFrom v2)