:: deftheorem Def15 defines semi-continuous GLIB_010:def 15 :
for G1, G2 being _Graph
for F being PGraphMapping of G1,G2 holds
( F is semi-continuous iff for e, v, w being object st e in dom (F _E) & v in dom (F _V) & w in dom (F _V) & (F _E) . e Joins (F _V) . v,(F _V) . w,G2 holds
e Joins v,w,G1 );