## $\Pi _{2}^{1}$ sets and $\Pi _{2}^{1}$ singletons

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- by Leo Harrington
- Proc. Amer. Math. Soc.
**52**(1975), 356-360 - DOI: https://doi.org/10.1090/S0002-9939-1975-0373896-5
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## Abstract:

The following are equivalent: (a) every real is constructible; (b) every nonempty $\prod _2^1$ set of reals contains a $\prod _2^1$ singleton. (Implication $({\text {a}}) \Rightarrow ({\text {b}})$ is due solely to H. Friedman.)## References

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## Bibliographic Information

- © Copyright 1975 American Mathematical Society
- Journal: Proc. Amer. Math. Soc.
**52**(1975), 356-360 - MSC: Primary 02K30
- DOI: https://doi.org/10.1090/S0002-9939-1975-0373896-5
- MathSciNet review: 0373896