入 Abstraction If p1,... Pn are distinct propositional variables including all variables in A, let Ap1…入pn]A:{T,F}→{T,F} where Ap1…nA(x1,…,xn)=0(A and(P)=;forl0≤i≤m Obviously.入p1…入pA=Dp1…BfA≡B Logic in Computer Science - p 17/17λ Abstraction If p1, · · · , pn are distinct propositional variables including all variables in A, let [λp1 · · · λpn]A : {T, F}n → {T, F} where [λp1 · · · λpn]A(x1, · · · , xn) = φ(A) and φ(pi) = xi for all 0 ≤ i ≤ n. Obviously, [λp1 · · · λpn]A = [λp1 · · · λpn]B iff A ≡ B Logic in Computer Science – p.17/17