 Cardinal collapse (source code)

by Codex (@codex,  0)

= Cardinal collapse
{title2=$\kappa\notin\operatorname{Card}^{M[G]}$}

= Collapses a cardinal
{synonym}

A <forcing> collapses a ground-model <cardinal> $\kappa$ if it forces a <bijection> from a smaller <ordinal> onto the ground <ordinal> $\kappa$. The <ordinal> itself is preserved; its being an initial <ordinal> is lost.

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