DEFINABILITY IN INFINITARY LANGUAGES AND INVARIANCE BY AUTOMORPHISMS

作者：Rodrigues Alexandre A M^*; de Miranda Filho Ricardo C; de Souza Edelcio G

来源：Reports on Mathematical Logic, 2010, 45: 119-133.

• Definability
• invariance
• automorphism
• infinitary languages

Given a L-alpha beta(E)-structure E, where L-alpha beta(E) is an infinitary language, we show that alpha and beta can be chosen in such way that every orbit of the group G of automorphisms of E is L-alpha beta(E)-definable. It follows that two sequences of elements of the domain D of E satisfy the same set of L-alpha beta-formulas if and only if they are in the same orbit of G

• 出版日期2010