580 -Cardinal arithmetic (11)

March 12, 2009

4. Strongly compact cardinals and {{\sf SCH}}

 

Definition 1 A cardinal {\kappa} is strongly compact iff it is uncountable, and any {\kappa}-complete filter (over any set {I}) can be extended to a {\kappa}-complete ultrafilter over {I.}

 

The notion of strong compactness has its origin in infinitary logic, and was formulated by Tarski as a natural generalization of the compactness of first order logic. Many distinct characterizations have been found.

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