Theories of modules closed under direct products
AbstractWe generalize to theories of modules (complete or not) a result of U. Felgner stating that a complete theory of abelian groups is a Horn theory if and only if it is closed under products. To prove this we show that a reduced product of modules ΠFMi (i ϵ I) is elementarily equivalent to a direct product of ultraproducts of the modules Mi(i ϵ I).
2001 ◽
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pp. 379-388
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1966 ◽
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1983 ◽
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