Theorem: betaReductionPreservesType (Nederpelt/STLC.lean)

State before:
V 𝕍 : Type
inst✝¹ : DecidableEq V
inst✝ : DecidableEq 𝕍
Γ : TCtxt V 𝕍
M M' : Λ V 𝕍
σ : 𝕋 𝕍
⊢ (M ↠ M') → (Γ ⊢ M : σ) → (Γ ⊢ M' : σ)
Tactic:
sorry
State after:
no goals