theorem Th87: :: GLIB_009:87

for G being _Graph
for E1, E2 being RepDEdgeSelection of G ex f being one-to-one Function st
( dom f = E1 & rng f = E2 & ( for e, v, w being object st e in E1 holds
( e DJoins v,w,G iff f . e DJoins v,w,G ) ) )