Independence-friendly logic

Independence-friendly logic (IF logic; proposed by Jaakko Hintikka and Gabriel Sandu in 1989) is an extension of classical first-order logic (FOL) by means of slashed quantifiers of the form ( ∃ v / V ) {\displaystyle (\exists v/V)} and ( ∀ v / V ) {\displaystyle (\forall v/V)} , where V {\displaystyle V} is a finite set of variables. The intended reading of ( ∃ v / V ) {\displaystyle (\exists v/V)} is "there is a v {\displaystyle v} which is functionally independent from the variables in V {\displaystyle V} ".

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