:: deftheorem defines SJoins GLIB_000:def 15 :
for G being _Graph
for X, Y being set
for e being object holds
( e SJoins X,Y,G iff ( e in the_Edges_of G & ( ( (the_Source_of G) . e in X & (the_Target_of G) . e in Y ) or ( (the_Source_of G) . e in Y & (the_Target_of G) . e in X ) ) ) );