Lean 4 fork for HoTT-compatible kernel extensions (Path types, transport, HITs). Maintained against upstream leanprover/lean4.
478be16fc5
This PR implements the option `mvcgen +jp` to employ a slightly lossy VC encoding for join points that prevents exponential VC blowup incurred by naïve splitting on control flow. ```lean def ifs_pure (n : Nat) : Id Nat := do let mut x := 0 if n > 0 then x := x + 1 else x := x + 2 if n > 1 then x := x + 3 else x := x + 4 if n > 2 then x := x + 1 else x := x + 2 if n > 3 then x := x + 1 else x := x + 2 if n > 4 then x := x + 1 else x := x + 2 if n > 5 then x := x + 1 else x := x + 2 return x theorem ifs_pure_triple : ⦃⌜True⌝⦄ ifs_pure n ⦃⇓ r => ⌜r > 0⌝⦄ := by unfold ifs_pure mvcgen +jp /- ... h✝⁵ : if n > 0 then x✝⁵ = 0 + 1 else x✝⁵ = 0 + 2 h✝⁴ : if n > 1 then x✝⁴ = x✝⁵ + 3 else x✝⁴ = x✝⁵ + 4 h✝³ : if n > 2 then x✝³ = x✝⁴ + 1 else x✝³ = x✝⁴ + 2 h✝² : if n > 3 then x✝² = x✝³ + 1 else x✝² = x✝³ + 2 h✝¹ : if n > 4 then x✝¹ = x✝² + 1 else x✝¹ = x✝² + 2 h✝ : if n > 5 then x✝ = x✝¹ + 1 else x✝ = x✝¹ + 2 ⊢ x✝ > 0 -/ grind ``` |
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