Distinguishing three strong saturation properties in nonstandard analysis Original Research Article

Three results in [14] and one in [8] are analyzed in Sections 3–6 in order to supply examples on Loeb probability spaces, which distinguish the different strength among three generalizations of k-saturation, as well to answer some questions in Section 7 of [15]. In Section 3 we show that not every automorphism of a Loeb algebra is induced by an internal permutation, in Section 4 we show that if the View the MathML source model axiom is true, then every automorphism of a Loeb algebra is induced by a point-automorphism, in Section 5 we show that not every measure-preserving homomorphism from a small subalgebra to a Loeb algebra is induced by an internal permutation, without assuming full-saturation, in Section 6 we show that, under some cardinality assumptions, the View the MathML source property does not guarantee the compactness of a Loeb space, and in Section 7 an application of the View the MathML source model axiom is given on the existence of ergodic transformations of a Loeb space, which partially answers Problem 2.3 of [5].