{
  "file_path": "D:\\Python\\Quantum\\research\\lean\\NguyenRH1\\NguyenRH1\\LiSkeleton.lean",
  "old_string": "/-- [SKELETON] Margin convexity (D-057, draft \u00a73.1 Step 4): for any",
  "new_string": "/-- [PROVED session 011] Second derivative of a sum (needs first-deriv\ndifferentiability at n and eventual differentiability near n). -/\ntheorem deriv2_add {f g : \u211d \u2192 \u211d} {n : \u211d}\n    (hf1 : DifferentiableAt \u211d (deriv f) n) (hg1 : DifferentiableAt \u211d (deriv g) n)\n    (hf2 : \u2200\u1da0 m in \ud835\udcdd n, DifferentiableAt \u211d f m)\n    (hg2 : \u2200\u1da0 m in \ud835\udcdd n, DifferentiableAt \u211d g m) :\n    deriv (deriv (f + g)) n = deriv (deriv f) n + deriv (deriv g) n := by\n  have he : deriv (f + g) =\u1da0[\ud835\udcdd n] (fun m => deriv f m + deriv g m) := by\n    filter_upwards [hf2, hg2] with m hfm hgm\n    exact deriv_add hfm hgm\n  have h2 : HasDerivAt (fun m => deriv f m + deriv g m)\n      (deriv (deriv f) n + deriv (deriv g) n) n := (hf1.add hg1).hasDerivAt\n  exact (h2.congr_of_eventuallyEq he.symm).deriv\n\n/-- [PROVED session 011] Second derivative of a constant multiple. -/\ntheorem deriv2_const_mul {f : \u211d \u2192 \u211d} {n : \u211d} (c : \u211d)\n    (hf1 : DifferentiableAt \u211d (deriv f) n)\n    (hf2 : \u2200\u1da0 m in \ud835\udcdd n, DifferentiableAt \u211d f m) :\n    deriv (deriv (fun m => c * f m)) n = c * deriv (deriv f) n := by\n  have he : deriv (fun m => c * f m) =\u1da0[\ud835\udcdd n] (fun m => c * deriv f m) := by\n    filter_upwards [hf2] with m hfm\n    exact deriv_const_mul c hfm\n  have h2 : HasDerivAt (fun m => c * deriv f m) (c * deriv (deriv f) n) n :=\n    (hf1.const_mul c).hasDerivAt\n  exact (h2.congr_of_eventuallyEq he.symm).deriv\n\n/-- [PROVED session 011] Second derivative of a constant function. -/\ntheorem deriv2_const_val (K n : \u211d) : deriv (deriv fun _ => K) n = 0 := by\n  have h1 : \u2200\u1da0 m in \ud835\udcdd n, HasDerivAt (fun _ => K) 0 m := by\n    filter_upwards [] with m\n    exact hasDerivAt_const m K\n  exact deriv2_of_hasDerivAt_nhds h1 (hasDerivAt_const n 0)\n\n/-- [PROVED session 011] Per-point first derivative of the S-function. -/\ntheorem hasDerivAt_marginS (c : \u211d) {m : \u211d} (hm : 0 < m) :\n    HasDerivAt (fun m => (1 / 2) * m * Real.log m + c * m - 4)\n      ((1 / 2) * (Real.log m + 1) + c) m := by\n  have hlog : HasDerivAt Real.log m\u207b\u00b9 m := Real.hasDerivAt_log (ne_of_gt hm)\n  have hml := ((hasDerivAt_id' m).const_mul (1 / 2)).mul hlog\n  have h := (hml.add ((hasDerivAt_id' m).const_mul c)).sub_const 4\n  have hm0 : m \u2260 0 := ne_of_gt hm\n  convert h using 2\n  field_simp [hm0]\n  ring\n\n/-- [PROVED session 011] Second derivative of the S-function: S\u2033 = 1/(2n). -/\ntheorem marginS_deriv2 (c : \u211d) {n : \u211d} (hn : 0 < n) :\n    deriv (deriv fun m => (1 / 2) * m * Real.log m + c * m - 4) n =\n      1 / (2 * n) := by\n  have h1 : \u2200\u1da0 m in \ud835\udcdd n, HasDerivAt (fun m => (1 / 2) * m * Real.log m + c * m - 4)\n      ((1 / 2) * (Real.log m + 1) + c) m := by\n    filter_upwards [eventually_gt_nhds hn] with m hm\n    exact hasDerivAt_marginS c hm\n  have h2 : HasDerivAt (fun m => (1 / 2) * (Real.log m + 1) + c) ((1 / 2) * m\u207b\u00b9) n := by\n    have h := ((Real.hasDerivAt_log (ne_of_gt hn)).add_const 1).const_mul (1 / 2)\n    convert h.add_const c using 2 <;> ring\n  exact deriv2_of_hasDerivAt_nhds h1 h2\n\n/-- [SKELETON] Margin convexity (D-057, draft \u00a73.1 Step 4): for any"
}