theorem Th27: :: LEXBFS:27
for G being _finite _Graph
for L being LexBFS:Labeling of G
for v being Vertex of G
for x being set
for k being Nat st x in G .AdjacentSet {v} & not x in dom (L `1) holds
((LexBFS:Update (L,v,k)) `2) . x = ((L `2) . x) \/ {((G .order()) -' k)}