for G1, G2 being _Graph
for F0 being PGraphMapping of G1,G2 st F0 _E is one-to-one holds
ex E being Subset of (the_Edges_of G2) st
for G3 being reverseEdgeDirections of G2,E ex F being PGraphMapping of G1,G3 st
( F = F0 & F is directed & ( F0 is weak_SG-embedding implies F is weak_SG-embedding ) & ( F0 is strong_SG-embedding implies F is strong_SG-embedding ) & ( F0 is isomorphism implies F is isomorphism ) )