Let T be a first order
theory. Two models are almost isomorphic if they are elementarily equivalent in the
language L∞,ω. We investigate the number of non almost-isomorphic models of T of
power λ as a function of λ,I(T,λ). We prove μ > λ ≧|T|,I(T,λ) ≦ λ implies
I(T,μ) ≦ I(T,λ). In fact, we generalize the downward Skolem-Lowenheim theorem
for infinitary languages. Th. (1, 4, 5).
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