Mad spectra

by Shelah and Spinas. [ShSi:1038]
J Symbolic Logic, 2015
The mad spectrum is the set of all cardinalities of infinite maximal almost disjoint families on omega . We treat the problem to characterize those sets A which, in some forcing extension of the universe, can be the mad spectrum. We solve this problem to some extent. What remains open is the possible values of min (A) and max (A) .

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