for G1 being _Graph
for G2 being Subgraph of G1
for X being set holds
( G2 .edgesInto X c= G1 .edgesInto X & G2 .edgesOutOf X c= G1 .edgesOutOf X & G2 .edgesInOut X c= G1 .edgesInOut X & G2 .edgesBetween X c= G1 .edgesBetween X )