 ##  [Sahlqvist Correspondence](/sahlqvist-correspondence) 

  ##  [Sahlqvist Correspondence](https://mathlogic.quantumdictionary.io/sahlqvist-correspondence-0) 

  
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- Natural &amp; Formal Sciences -

**Mathematics &amp; Logic Dictionary**

 
Definition

A syntactic method in modal logic identifying a wide class of modal formulas (Sahlqvist formulas) that enjoy guaranteed first-order frame correspondents and canonical completeness: each Sahlqvist formula corresponds effectively to a first-order condition on frames and generates a canonical axiom whose addition yields completeness for the corresponding frame class.