R. Cauty et T. Dobrowolski, APPLYING COORDINATE PRODUCTS TO THE TOPOLOGICAL IDENTIFICATION OF NORMED SPACES, Transactions of the American Mathematical Society, 337(2), 1993, pp. 625-649
Using the l2-products we find pre-Hilbert spaces that are absorbing se
ts for all Borelian classes of order alpha greater-than-or-equal-to 1
. We also show that the following spaces are homeomorphic to SIGMA(inf
inity), the countable product of the space SIGMA = {(x(n)) is-an-eleme
nt-of R(infinity) : (x(n)) is bounded} : (1) every coordinate product
PI(C) H(n) of normed spaces H(n) in the sense of a Banach space C , wh
ere each H(n) is an absolute F(sigmadelta)-set and infinitely many of
the H(n) 's are Z(sigma)-spaces, (2) every function space L(p) = and(p
'<p) L(p') with the L(q)-topology, 0 < q < p less-than-or-equal-to inf
inity. (3) every sequence space l(p) = and(p<p') l(p') with the l(q)-t
opology, 0 less-than-or-equal-to p < q < infinity. We also note that e
ach additive and multiplicative Borelian class of order alpha greater-
than-or-equal-to 2 , each projective class, and the class of nonprojec
tive spaces contain uncountably many topologically different pre-Hilbe
rt spaces which are Z(sigma)-spaces.