theorem :: GLIB_006:140

for G being non _trivial _Graph
for v1, e being object
for v2 being Vertex of G
for G1 being addAdjVertex of G,v1,e,v2
for G2 being removeVertex of G1,v2
for G3 being removeVertex of G,v2 st not e in the_Edges_of G & not v1 in the_Vertices_of G holds
G2 is addVertex of G3,v1