Lm1:
for G being EGraph holds dom (the_ELabel_of G) c= the_Edges_of G
Lm2:
for G being VGraph holds dom (the_VLabel_of G) c= the_Vertices_of G
Lm3:
for G being _Graph
for X being set holds
( G .set (WeightSelector,X) == G & G .set (ELabelSelector,X) == G & G .set (VLabelSelector,X) == G )
Lm4:
for x, y, X, Y being set
for f being PartFunc of X,Y st x in X & y in Y holds
f +* (x .--> y) is PartFunc of X,Y