Unfoldable cardinal

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In mathematics, an unfoldable cardinal is a certain kind of large cardinal number.

Formally, a cardinal number κ is λ-unfoldable if and only if for every standard model M of cardinality κ of ZFC-minus-power set, such that κ is in M, there is a non-trivial elementary embedding j of M into a standard model with the critical point of j being κ and j(κ) ≥ λ.

A cardinal is unfoldable if and only if it is λ-unfoldable for all ordinals λ.