Изменения

** $π_{FirstName}(σ_{Name=M34391}(π_{FirstName, Name}(S × G))) ⇒ $** $π_{FirstName}(π_{FirstName, Name}(σ_{Name=M34391}(S × G))) ⇒ $** $π_{FirstName}(σ_{Name=M34391}(S × G))$

**$σ_{P_1.p > P_2.p ∧ P_2.p ≥ 60}(P_1 ⋈_{P_1.SId = P_2.SId} P_2) ⇒$**$σ_{P_1.p > P_2.p ∧ P_2.p ≥ 60 ∧ P_1.p > 60}(P_1 ⋈_{P_1.SId = P_2.SId} P_2) ⇒$**$σ_{P_1.p > P_2.p}(σ_{p > 60}(P_1) ⋈_{P_1.SId = P_2.SId} σ_{p ≥ 60}(P_2))$