| Flat_RVar : ∀ Γ Δ σ l, Rule_Flat (RVar Γ Δ σ l)
| Flat_RLam : ∀ Γ Δ Σ tx te q , Rule_Flat (RLam Γ Δ Σ tx te q )
| Flat_RCast : ∀ Γ Δ Σ σ τ γ q , Rule_Flat (RCast Γ Δ Σ σ τ γ q )
| Flat_RVar : ∀ Γ Δ σ l, Rule_Flat (RVar Γ Δ σ l)
| Flat_RLam : ∀ Γ Δ Σ tx te q , Rule_Flat (RLam Γ Δ Σ tx te q )
| Flat_RCast : ∀ Γ Δ Σ σ τ γ q , Rule_Flat (RCast Γ Δ Σ σ τ γ q )