theorem :: GLIB_012:43

for G2 being _Graph
for V being Subset of (the_Vertices_of G2)
for G1 being addLoops of G2,V
for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 & v1 in V holds
( v1 .inDegree() = (v2 .inDegree()) +` 1 & v1 .outDegree() = (v2 .outDegree()) +` 1 & v1 .degree() = (v2 .degree()) +` 2 )