let G1 be _Graph; :: thesis: for G2 being G1 -isomorphic _Graph
for G3 being GraphComplement of G1
for G4 being GraphComplement of G2 holds G4 is G3 -isomorphic
let G2 be G1 -isomorphic _Graph; :: thesis: for G3 being GraphComplement of G1
for G4 being GraphComplement of G2 holds G4 is G3 -isomorphic
let G3 be GraphComplement of G1; :: thesis: for G4 being GraphComplement of G2 holds G4 is G3 -isomorphic
let G4 be GraphComplement of G2; :: thesis: G4 is G3 -isomorphic
set G5 = the SimpleGraph of G1;
set G6 = the SimpleGraph of G2;
the SimpleGraph of G2 is the SimpleGraph of G1 -isomorphic by GLIB_010:172;
hence G4 is G3 -isomorphic by Th102; :: thesis: verum