Correct cardinal: Difference between revisions
Jump to navigation
Jump to search
Content added Content deleted
(Created page with "A \(\Sigma_n\)-correct cardinal is a cardinal \(\kappa\) such that \(V_\kappa\) is a \(\Sigma_n\)-elementary substructure of \(V\), where \(\Sigma_n\) is from the Lévy hierarchy.{{citation needed}} A regular cardinal is \(\Sigma_2\)-correct iff for every first-order formula \(\phi(x)\) and any \(x\in H_\kappa\), if \(\exists\alpha(H_\alpha\vDash\phi(x)\)<ref>, then there is a \(\beta<\kappa\) such that \(H_\beta\vDash\phi(x)\). [https://logicdavid.github.io/files/mthes...") |
No edit summary |
||
Line 1: | Line 1: | ||
A \(\Sigma_n\)-correct cardinal is a cardinal \(\kappa\) such that \(V_\kappa\) is a \(\Sigma_n\)-elementary substructure of \(V\), where \(\Sigma_n\) is from the Lévy hierarchy.{{citation needed}} |
A \(\Sigma_n\)-correct cardinal is a cardinal \(\kappa\) such that \(V_\kappa\) is a \(\Sigma_n\)-elementary substructure of \(V\), where \(\Sigma_n\) is from the Lévy hierarchy.{{citation needed}} |
||
A regular cardinal is \(\Sigma_2\)-correct iff for every first-order formula \(\phi(x)\) and any \(x\in H_\kappa\), if \(\exists\alpha(H_\alpha\vDash\phi(x)\) |
A regular cardinal is \(\Sigma_2\)-correct iff for every first-order formula \(\phi(x)\) and any \(x\in H_\kappa\), if \(\exists\alpha(H_\alpha\vDash\phi(x))\), then there is a \(\beta<\kappa\) such that \(H_\beta\vDash\phi(x)\). <ref>[https://logicdavid.github.io/files/mthesis.pdf#page=21]</ref> |
Revision as of 06:38, 2 October 2023
A \(\Sigma_n\)-correct cardinal is a cardinal \(\kappa\) such that \(V_\kappa\) is a \(\Sigma_n\)-elementary substructure of \(V\), where \(\Sigma_n\) is from the Lévy hierarchy.[Citation needed]
A regular cardinal is \(\Sigma_2\)-correct iff for every first-order formula \(\phi(x)\) and any \(x\in H_\kappa\), if \(\exists\alpha(H_\alpha\vDash\phi(x))\), then there is a \(\beta<\kappa\) such that \(H_\beta\vDash\phi(x)\). [1]