Expansion and Extension 1. If 2 is an expansion of fi, then Th(Fi)c Th(F2) 2.f2UI2 is a conservative extension of升1∪I1, en Th(F1∪I)=Th(F2∪I2)nC(1) Logic in Computer Science - p 8/21Expansion and Extension 1. If F2 is an expansion of F1, then Th(F1) ⊆ Th(F2). 2. If F2 S Γ2 is a conservative extension of F1 S Γ1, then Th(F1 ∪ Γ1) = Th(F2 ∪ Γ2) ∩ L(F1) Logic in Computer Science – p.8/21