Well-formed formulas The set of wffs is the intersection of all sets s of formulas such that 1. pE S for each propositional variable p 2. For each formula a,fA∈S,then(~A)∈S 3. For all formulas a and B,ifA∈ s and e∈S, then(A∨B)∈S a wff is a member of the set of wffs Logic in Computer Science- p 4/39Well-Formed Formulas The set of wffs is the intersection of all sets S of formulas such that: 1. p ∈ S for each propositional variable p 2. For each formula A, if A ∈ S, then (∼ A) ∈ S 3. For all formulas A and B, if A ∈ S and B ∈ S, then (A ∨ B) ∈ S A wff is a member of the set of wffs. Logic in Computer Science – p.4/39