let V be RealUnitarySpace; :: thesis: TopStruct(# the carrier of V,(Family_open_set V) #) is TopSpace
set T = TopStruct(# the carrier of V,(Family_open_set V) #);
A1: for p, q being Subset of TopStruct(# the carrier of V,(Family_open_set V) #) st p in the topology of TopStruct(# the carrier of V,(Family_open_set V) #) & q in the topology of TopStruct(# the carrier of V,(Family_open_set V) #) holds
p /\ q in the topology of TopStruct(# the carrier of V,(Family_open_set V) #) by Th39;
( the carrier of TopStruct(# the carrier of V,(Family_open_set V) #) in the topology of TopStruct(# the carrier of V,(Family_open_set V) #) & ( for a being Subset-Family of TopStruct(# the carrier of V,(Family_open_set V) #) st a c= the topology of TopStruct(# the carrier of V,(Family_open_set V) #) holds
union a in the topology of TopStruct(# the carrier of V,(Family_open_set V) #) ) ) by Th38, Th40;
hence TopStruct(# the carrier of V,(Family_open_set V) #) is TopSpace by A1, PRE_TOPC:def 1; :: thesis: verum