Skip to main content
2 of 2
edited tags
Trevor Wilson
  • 5.5k
  • 29
  • 46

Definable Wellordering of the Reals

Why are we interested in definable wellordering of the reals? For instance, we have

  1. Con(ZFC) $\Rightarrow$ Con(ZFC + there is a $\Delta^1_2$-wellordering of $\mathbb{R}$),
  2. Con(ZFC + there is a measurable cardinal) $\Rightarrow$ Con(ZFC + there is a measurable cardinal+there is a $\Delta^1_3$-wellordering of $\mathbb{R}$).
tzy
  • 81
  • 2