# Mathematical Logic Quarterly

## Choices of Convenient Sets

### Abstract

Proceeding in the theory with extensionality, comprehension for classes, existence of the empty set and the assumption the addition of one element to a set makes again a set (others usual set‐theoretical operations are not required) we show a week assumption which guarantees existence of a saturated elementary extension (with absolute ϵ) of the system of hereditarily finite sets.

Mathematics Subject Classification: 03C62, 03C50, 03E70.

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