C onsequence Definition Let 2 be a(possibly infinite)set of propositions. We say that o is a consequence of∑( and write as∑ha), for any valuation v (D()= T for allT∈∑)→()=TConsequence . Definition . . Let Σ be a (possibly infinite) set of propositions. We say that σ is a consequence of Σ (and write as Σ |= σ) if, for any valuation V, (V(τ ) = T for all τ ∈ Σ) ⇒ V(σ) = T. Yi Li (Fudan University) Discrete Mathematics April 23, 2013 4 / 25