theorem :: LOPBAN13:29
for X, Y, Z being RealNormSpace ex I being BilinearOperator of (R_NormSpace_of_BoundedLinearOperators (X,Y)),(R_NormSpace_of_BoundedLinearOperators (Y,Z)),(R_NormSpace_of_BoundedLinearOperators (X,Z)) st
( I is_continuous_on the carrier of [:(R_NormSpace_of_BoundedLinearOperators (X,Y)),(R_NormSpace_of_BoundedLinearOperators (Y,Z)):] & ( for u being Point of (R_NormSpace_of_BoundedLinearOperators (X,Y))
for v being Point of (R_NormSpace_of_BoundedLinearOperators (Y,Z)) holds I . (u,v) = v * u ) )