46XX 


Functional analysis {For manifolds modeled on topological linear spaces, see 57Nxx, 58Bxx} 

46Cxx 

Inner product spaces and their generalizations, Hilbert spaces {For function spaces, see 46Exx} 


46C05 
Hilbert and preHilbert spaces: geometry and topology (including spaces with semidefinite inner product) 


46C07 
Hilbert subspaces (= operator ranges); complementation (Aronszajn, de Branges, etc.) [See also 46B70, 46M35] 


46C15 
Characterizations of Hilbert spaces 


46C20 
Spaces with indefinite inner product (Kreĭn spaces, Pontryagin spaces, etc.) [See also 47B50] 


46C50 
Generalizations of inner products (semiinner products, partial inner products, etc.) 


46C99 
None of the above, but in this section 