If T1 and T2 are two topologies on the same space X, then O TINT2 is a topology on X but T1UT2 is not O TINT2 and T1UT2 are both topologies on X O TINT2 and T1UT2 both cannot be topologies on X O...

Extracted text: If T1 and T2 are two topologies on the same space X, then O TINT2 is a topology on X but T1UT2 is not O TINT2 and T1UT2 are both topologies on X O TINT2 and T1UT2 both cannot be topologies on X O TIUT2 is a topology on X but T1NT2 is not