File size: 17,500 Bytes
1c3ffd8 |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 |
import Mathlib
import Mathlib.Analysis.SpecialFunctions.Pow.Real
set_option linter.unusedVariables.analyzeTactics true
open Real Set
lemma mylemma_1
(x a: β β β)
(hxp: β (i : β), 0 < x i)
(hβ: β (n : β),
1 β€ n β§ n β€ 2023 β
a n = sqrt ((Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k)
* Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k)) :
β (n : β), (1 β€ n β§ n β€ 2022) β a (n) < a (n + 1) := by
intros n hn
have hβ: a n = sqrt ((Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k)
* Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k) := by
refine hβ n ?_
constructor
. exact hn.1
linarith
have hβ: a (n + 1) = sqrt ((Finset.sum (Finset.Ico 1 (n + 2)) fun k => x k)
* Finset.sum (Finset.Ico 1 (n + 2)) fun k => 1 / x k) := by
refine hβ (n + 1) ?_
constructor
. linarith
linarith
rw [hβ,hβ]
refine sqrt_lt_sqrt ?_ ?_
. refine le_of_lt ?_
refine mul_pos ?_ ?_
. refine Finset.sum_pos ?_ ?_
. exact fun i _ => hxp i
. simp
linarith
. refine Finset.sum_pos ?_ ?_
intros i _
exact one_div_pos.mpr (hxp i)
. simp
linarith
have gβ: 1 β€ n + 1 := by linarith
rw [Finset.sum_Ico_succ_top gβ _, Finset.sum_Ico_succ_top gβ _]
repeat rw [add_mul, mul_add]
have hβ: 0 < (Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k) * (1 / x (n + 1)) +
x (n + 1) * ((Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k) + 1 / x (n + 1)) := by
refine add_pos ?_ ?_
. refine mul_pos ?_ ?_
. refine Finset.sum_pos ?_ ?_
. exact fun i _ => hxp i
. simp
linarith
. exact one_div_pos.mpr (hxp (n + 1))
. refine mul_pos ?_ ?_
. exact hxp (n + 1)
. refine add_pos ?_ ?_
. refine Finset.sum_pos ?_ ?_
. intros i _
exact one_div_pos.mpr (hxp i)
. simp
linarith
exact one_div_pos.mpr (hxp (n + 1))
linarith
lemma mylemma_amgm
(b1 b2 b3 b4 :β)
(hb1: 0 β€ b1)
(hb2: 0 β€ b2)
(hb3: 0 β€ b3)
(hb4: 0 β€ b4) :
(4 * (b1 * b2 * b3 * b4) ^ (4:β)β»ΒΉ β€ b1 + b2 + b3 + b4) := by
let w1 : β := (4:β)β»ΒΉ
let w2 : β := w1
let w3 : β := w2
let w4 : β := w3
rw [mul_comm]
refine mul_le_of_le_divβ ?_ (by norm_num) ?_
. refine add_nonneg ?_ hb4
refine add_nonneg ?_ hb3
exact add_nonneg hb1 hb2
have hβ: (b1^w1 * b2^w2 * b3^w3 * b4^w4) β€ w1 * b1 + w2 * b2 + w3 * b3 + w4 * b4 := by
refine geom_mean_le_arith_mean4_weighted (by norm_num) ?_ ?_ ?_ hb1 hb2 hb3 hb4 ?_
. norm_num
. norm_num
. norm_num
. norm_num
repeat rw [mul_rpow _]
ring_nf at *
linarith
repeat { assumption }
. exact mul_nonneg hb1 hb2
. exact hb4
. refine mul_nonneg ?_ hb3
exact mul_nonneg hb1 hb2
lemma mylemma_2
(x a: β β β)
(hxp: β (i : β), 0 < x i)
(hβ: β (n : β),
1 β€ n β§ n β€ 2023 β
a n = sqrt ((Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k)
* (Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k)))
(n: β)
(hn: 1 β€ n β§ n β€ 2021) :
(4 * a n β€
(Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k) * (1 / x (n + 1) + 1 / x (n + 2)) +
(x (n + 1) + x (n + 2)) * Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k) := by
repeat rw [mul_add, add_mul]
have gββ: 0 β€ Finset.sum (Finset.Ico 1 (1 + n)) fun x_1 => x x_1 := by
refine le_of_lt ?_
refine Finset.sum_pos ?_ ?_
. exact fun i _ => hxp i
. simp
linarith
have gββ: 0 β€ Finset.sum (Finset.Ico 1 (1 + n)) fun x_1 => (x x_1)β»ΒΉ := by
refine le_of_lt ?_
refine Finset.sum_pos ?_ ?_
. intros i _
exact inv_pos.mpr (hxp i)
. simp
linarith
have hββ: 4 * ( ((Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k) * (1 / x (n + 1))) *
((Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k) * (1 / x (n + 2))) *
((x (n + 1) * Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k)) *
(x (n + 2) * Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k) ) ^ (4:β)β»ΒΉ
β€ (Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k) * (1 / x (n + 1)) +
(Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k) * (1 / x (n + 2)) +
((x (n + 1) * Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k) +
x (n + 2) * Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k) := by
let b1:β := (Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k) * (1 / x (n + 1))
let b2:β := (Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k) * (1 / x (n + 2))
let b3:β := (x (n + 1) * Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k)
let b4:β := x (n + 2) * (Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k)
have hb1: b1 = (Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k) * (1 / x (n + 1)) := by
exact rfl
have hb2: b2 = (Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k) * (1 / x (n + 2)) := by
exact rfl
have hb3: b3 = (x (n + 1) * Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k) := by
exact rfl
have hb4: b4 = x (n + 2) * (Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k) := by
exact rfl
rw [β hb1, β hb2, β hb3, β hb4]
have gβ: 4 * (b1 * b2 * b3 * b4) ^ (4:β)β»ΒΉ β€ b1 + b2 + b3 + b4 := by
have b1p: 0 β€ b1 := by
rw [hb1]
refine mul_nonneg ?_ ?_
. ring_nf
exact gββ
. refine le_of_lt ?_
exact one_div_pos.mpr (hxp (n + 1))
have b2p: 0 β€ b2 := by
rw [hb2]
refine mul_nonneg ?_ ?_
. ring_nf
exact gββ
. refine le_of_lt ?_
exact one_div_pos.mpr (hxp (n + 2))
have b3p: 0 β€ b3 := by
rw [hb3]
refine mul_nonneg ?_ ?_
. exact LT.lt.le (hxp (n + 1))
. ring_nf
exact gββ
have b4p: 0 β€ b4 := by
rw [hb4]
refine mul_nonneg ?_ ?_
. exact LT.lt.le (hxp (n + 2))
. ring_nf
exact gββ
exact mylemma_amgm b1 b2 b3 b4 b1p b2p b3p b4p
linarith
have hββ: 4 * a (n) = 4 * (((Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k) * (1 / x (n + 1))) *
((Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k) * (1 / x (n + 2))) *
((x (n + 1) * Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k)) *
(x (n + 2) * Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k) ) ^ (4:β)β»ΒΉ := by
simp
ring_nf
have gβ: (Finset.sum (Finset.Ico 1 (1 + n)) fun x_1 => x x_1) ^ 2
* x (1 + n) * (x (1 + n))β»ΒΉ * x (2 + n) * (x (2 + n))β»ΒΉ *
(Finset.sum (Finset.Ico 1 (1 + n)) fun x_1 => (x x_1)β»ΒΉ) ^ 2
= x (1 + n) * (x (1 + n))β»ΒΉ * x (2 + n) * (x (2 + n))β»ΒΉ *
(Finset.sum (Finset.Ico 1 (1 + n)) fun x_1 => x x_1) ^ 2 *
(Finset.sum (Finset.Ico 1 (1 + n)) fun x_1 => (x x_1)β»ΒΉ) ^ 2 := by
linarith
have gβ: x (1 + n) * (x (1 + n))β»ΒΉ * x (2 + n) * (x (2 + n))β»ΒΉ = 1 := by
rw [mul_assoc]
have ggβ: x (1 + n) * (x (1 + n))β»ΒΉ = 1 := by
refine div_self ?_
exact ne_of_gt (hxp (1 + n))
have ggβ: x (2 + n) * (x (2 + n))β»ΒΉ = 1 := by
refine div_self ?_
exact ne_of_gt (hxp (2 + n))
rw [ggβ, ggβ]
norm_num
rw [gβ] at gβ
rw [gβ]
simp
repeat rw [mul_rpow]
have gβ: ((Finset.sum (Finset.Ico 1 (1 + n)) fun x_1 => x x_1) ^ (2:β)) ^ (4:β)β»ΒΉ
= (Finset.sum (Finset.Ico 1 (1 + n)) fun x_1 => x x_1) ^ (1/(2:β)) := by
rw [β rpow_mul gββ (2:β) (4:β)β»ΒΉ]
norm_num
have gβ: ((Finset.sum (Finset.Ico 1 (1 + n)) fun x_1 => (x x_1)β»ΒΉ) ^ (2:β)) ^ (4:β)β»ΒΉ
= (Finset.sum (Finset.Ico 1 (1 + n)) fun x_1 => (x x_1)β»ΒΉ) ^ (1/(2:β)) := by
rw [β rpow_mul gββ (2:β) (4:β)β»ΒΉ]
norm_num
-- rw [gβ, β sqrt_eq_rpow (Finset.sum (Finset.Ico 1 (1 + n)) fun x_1 => x x_1)]
-- rw [gβ, β sqrt_eq_rpow (Finset.sum (Finset.Ico 1 (1 + n)) fun x_1 => (x x_1)β»ΒΉ)]
have gβ: a (n) = sqrt ((Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k)
* Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k) := by
refine hβ n ?_
constructor
. exact hn.1
. linarith
norm_cast at *
rw [gβ, gβ, β mul_rpow]
rw [β sqrt_eq_rpow]
ring_nf at gβ
exact gβ
. exact gββ
. exact gββ
. exact sq_nonneg (Finset.sum (Finset.Ico 1 (1 + n)) fun x_1 => x x_1)
. exact sq_nonneg (Finset.sum (Finset.Ico 1 (1 + n)) fun x_1 => (x x_1)β»ΒΉ)
exact Eq.trans_le hββ hββ
lemma mylemma_3
(x a: β β β)
(hxp: β (i : β), 0 < x i)
(hx: β (i j : β), i β j β x i β x j)
(hβ: β (n : β),
1 β€ n β§ n β€ 2023 β
a n = sqrt ((Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k)
* (Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k)))
(hββ: β (n : β), 1 β€ n β§ n β€ 2023 β 0 < a n) :
(β (n : β), 1 β€ n β§ n β€ 2021 β a n + 2 < a (n + 2)) := by
intros n hn
have gβ: 0 β€ a n + 2 := by
refine le_of_lt ?_
refine add_pos ?_ (by norm_num)
refine hββ n ?_
constructor
. exact hn.1
. linarith
have gβ: 0 β€ a (n + 2) := by
refine le_of_lt ?_
refine hββ (n + 2) ?_
constructor
. linarith
. linarith
rw [β sqrt_sq gβ, β sqrt_sq gβ]
have gβ: 0 β€ (a n + 2) ^ 2 := by exact sq_nonneg (a n + 2)
-- simp
refine Real.sqrt_lt_sqrt gβ ?_
have gβ: 0 β€ ((Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k)
* (Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k)) := by
refine le_of_lt ?_
refine mul_pos ?_ ?_
. refine Finset.sum_pos ?_ ?_
. exact fun i _ => hxp i
. simp
linarith
. refine Finset.sum_pos ?_ ?_
. intros i _
exact one_div_pos.mpr (hxp i)
. simp
linarith
have gnβ: a (n) ^ 2 = ((Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k)
* (Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k)) := by
rw [β sq_sqrt gβ]
have gβ: 0 β€ a n := by
refine le_of_lt ?_
refine hββ n ?_
constructor
. exact hn.1
. linarith
refine (sq_eq_sqβ gβ ?_).mpr ?_
. exact
sqrt_nonneg
((Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k) *
Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k)
. refine hβ (n) ?_
constructor
. exact hn.1
. linarith
have gnβ: a (n + 2) = sqrt ((Finset.sum (Finset.Ico 1 (n + 2 + 1)) fun k => x k)
* Finset.sum (Finset.Ico 1 (n + 2 + 1)) fun k => 1 / x k) := by
refine hβ (n + 2) ?_
constructor
. linarith
. linarith
rw [add_sq, gnβ, sq_sqrt]
. have gaβ: 1 β€ n + 2 := by linarith
rw [Finset.sum_Ico_succ_top gaβ _, Finset.sum_Ico_succ_top gaβ _]
have gaβ: 1 β€ n + 1 := by linarith
rw [Finset.sum_Ico_succ_top gaβ _, Finset.sum_Ico_succ_top gaβ _]
rw [add_assoc, add_assoc, add_assoc]
rw [add_mul, mul_add]
rw [β gnβ]
repeat rw [add_assoc]
refine add_lt_add_left ?_ (a (n) ^ 2)
rw [mul_add (x (n + 1) + x (n + 2))]
have hβ: 4 < (x (n + 1) + x (n + 2)) * (1 / x (n + 1) + 1 / x (n + 2)) := by
repeat rw [add_mul, mul_add, mul_add]
repeat rw [mul_div_left_comm _ 1 _, one_mul]
repeat rw [div_self ?_]
. have hcβ: x (n + 1) * x (n + 2) * (x (n + 1) / x (n + 2))
= x (n + 1) * x (n + 1) := by
rw [mul_assoc, β mul_div_assoc, mul_div_right_comm, div_self ?_]
simp
exact ne_of_gt (hxp (n + 2))
have hcβ: x (n + 1) * x (n + 2) * (x (n + 2) / x (n + 1))
= x (n + 2) * x (n + 2) := by
rw [mul_comm (x (n + 1)) (x (n + 2)), mul_assoc, β mul_div_assoc, mul_div_right_comm, div_self ?_]
simp
exact ne_of_gt (hxp (n + 1))
have hββ: 0 < x (n + 1) * x (n + 2) := by
refine mul_pos ?_ ?_
. exact hxp (n + 1)
. exact hxp (n + 2)
have hββ: 2 < x (n + 1) / x (n + 2) + x (n + 2) / x (n + 1) := by
refine lt_of_mul_lt_mul_left ?_ (le_of_lt hββ)
rw [mul_add, hcβ, hcβ, β sq, β sq]
refine lt_of_sub_pos ?_
have ghββ: x (n + 1) ^ 2 + x (n + 2) ^ 2 - x (n + 1) * x (n + 2) * 2
= (x (n + 1) - x (n + 2)) ^ 2 := by
rw [sub_sq]
linarith
rw [ghββ]
refine (sq_pos_iff).mpr ?_
refine sub_ne_zero.mpr ?_
exact hx (n+1) (n+2) (by linarith)
linarith
. exact ne_of_gt (hxp (n + 2))
. exact ne_of_gt (hxp (n + 1))
clear gnβ gnβ gβ gβ gβ gβ gaβ gaβ
have hβ: 4 * a (n) β€ (Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k)
* (1 / x (n + 1) + 1 / x (n + 2)) +
((x (n + 1) + x (n + 2))
* Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k) := by
exact mylemma_2 (fun k => x k) a hxp hβ n hn
linarith
. refine mul_nonneg ?_ ?_
. refine Finset.sum_nonneg ?_
intros i _
exact LT.lt.le (hxp i)
. refine Finset.sum_nonneg ?_
intros i _
simp
exact LT.lt.le (hxp i)
theorem imo_2023_p4
(x : β β β)
(a : β β β)
(hxp: β (i: β), (0 < x i) )
(hx: β (i j: β), (i β j) β (x i β x j) )
(hβ: β (n:β), (1 β€ n β§ n β€ 2023) β
a n = Real.sqrt ( (Finset.sum (Finset.Ico 1 (n + 1)) fun (k : β) => (x k))
* (Finset.sum (Finset.Ico 1 (n + 1)) fun (k : β) => 1 / (x k)) ) )
(hβ: β (n:β), (1 β€ n β§ n β€ 2023) β β (kz:β€), (a n = βkz )) :
(3034 β€ a 2023) := by
have ha1: a 1 = 1 := by
have gβ: sqrt ((Finset.sum (Finset.Ico 1 (1 + 1)) fun k => x k)
* Finset.sum (Finset.Ico 1 (1 + 1)) fun k => 1 / x k) = 1 := by
norm_num
refine div_self ?_
exact ne_of_gt (hxp 1)
rw [β gβ]
exact hβ (1) (by norm_num)
have hββ: β (n : β), (1 β€ n β§ n β€ 2023) β 0 < a n := by
intros n hn
have ha: a n = sqrt ((Finset.sum (Finset.Ico 1 (n + 1)) fun k => x k)
* Finset.sum (Finset.Ico 1 (n + 1)) fun k => 1 / x k) := by
exact hβ (n) (hn)
rw [ha]
refine Real.sqrt_pos.mpr ?_
refine mul_pos ?_ ?_
. refine Finset.sum_pos ?_ ?_
. intros i _
exact hxp i
simp
linarith
. refine Finset.sum_pos ?_ ?_
. intros i _
exact one_div_pos.mpr (hxp i)
simp
linarith
have hββ: β (n : β), (1 β€ n β§ n β€ 2023) β β (kn:β), a n = βkn := by
intros n hn
have gββ: 0 < a n := by
exact hββ n hn
let β¨p, gpβ© := hβ n hn
let q:β := Int.toNat p
have gββ: βq = p := by
refine Int.toNat_of_nonneg ?_
rw [gp] at gββ
norm_cast at gββ
exact Int.le_of_lt gββ
use q
rw [gp]
norm_cast
exact id gββ.symm
have hββ: β (n:β), (1 β€ n β§ n β€ 2021) β a n + 2 < a (n+2) := by
exact fun n a_1 => mylemma_3 (fun i => x i) a hxp hx hβ hββ n a_1
have hβ: β (n:β), (1 β€ n β§ n β€ 2021) β a n + 3 β€ a (n+2) := by
intros n hn
have gβ: a n + 2 < a (n + 2) := by exact hββ n hn
have gββ: β (p:β), a n = βp := by
apply hββ
constructor
. linarith
. linarith
have gββ: β (q:β), a (n + 2) = βq := by
apply hββ
constructor
. linarith
. linarith
let β¨p, _β© := gββ
let β¨q, _β© := gββ
have gβ: p + 2 < q := by
suffices gββ: βp + (2:β) < βq
. norm_cast at gββ
. linarith
have gβ: βp + (3:β) β€ βq := by norm_cast
linarith
have hβ: β (n:β), (0 β€ n β§ n β€ 1010) β a 1 + 3 * (β(n) + 1) β€ a (3 + 2 * n) := by
intros n hn
induction' n with d hd
Β· simp
exact hβ (1) (by norm_num)
Β· rw [mul_add]
simp
have gβ: a (3 + 2 * d) + 3 β€ a (3 + 2 * (d + 1)) := by
refine hβ (3 + 2 * d) ?_
constructor
. linarith
. linarith
have gβ: a 1 + 3 * (βd + 1) + 3 β€ a (3 + 2 * d) + 3 := by
refine add_le_add_right ?_ (3)
apply hd
constructor
. linarith
. linarith
refine le_trans (by linarith[gβ]) gβ
rw [ha1] at hβ
have hβ: (3034:β) = 1 + 3 * (β1010 + 1) := by norm_num
rw [hβ]
exact hβ (1010) (by norm_num)
|