The Number of Countable Models of a Complete Theory and of Its Inessential Extension
摘要
It is proved that (a) there exists a complete countable theory having 2ω countable models, some inessential extension of which has ω countable models, and that (b) there exists a complete countable theory having 2ω countable models, some inessential extension of which has finitely many countable models. This gives an answer to the question of A. D. Taimanov.