Truth Definition(Truth The truth of a sentence p of L in a structure A in which every a E A is named by a ground term of l is defined by inductionTruth . Definition (Truth) . . The truth of a sentence φ of L in a structure A in which every a ∈ A is named by a ground term of L is defined by induction. 7. A |= ∃vφ(v) ⇔ for some ground term t, A |= φ(t). 8. A |= ∀vφ(v) ⇔ for all ground term t, A |= φ(t). Yi Li (Fudan University) Discrete Mathematics May 28, 2013 5 / 24