How is work on 8-man tablebases progressing?

[hgm]

I computed the size requirements without and with reducing using permutations of same pieces to illustrate.
Note that the number for reducing is just an approximation, dividing by the number of permutations of like pieces for those endgames.
Last on each line is the percentage of space you need if you don't use like-piece symmetry.

3: 524288 524288 100
4: 306184192 290979840 105
5: 96921976832 79135331668 122
6: 22360673484800 14305093222384 156
7: 4218203345518592 1947456033067182 216
8: 690330986839277568 213529294167604807 323
9: 101523728307603898368 19652448336691703337 516
10: 13728689646745625296896 1561065282681230985761 879
11: 1734484955477896291418112 109176580993481410741492 1588
12: 207127250281663267673735168 6824378818319881564216564 3035

I suppose the largest reduction is from permuting mupltiple Pawns, and when you would work by P-slice, you would exploit that automatically. So the only real question is how much you would save due to equivalence of permutations of the other pieces.

[mosfel24]

Well, at least I don't see any point in spending half the effort to do something half.

That is already a really weird attitude; half the job done without introducing any loss of efficiency should be considered a good start.

It becomes an even more counter-productive stance when you apply it to doing, say, 99% of the job for 1% of the effort. Especially if the remaining 1% concerns only cases that no one is interested in.

Your pi metaphor sucks. You should have said "no point in calculating the first 12 digits of pi when you cannot calculate the next million digits". Engineers would not agree...

Engineers seem fine with chess engines, which do 99% of the job for 1% of the effort.

[Koistinen]

I suppose the largest reduction is from permuting mupltiple Pawns, and when you would work by P-slice, you would exploit that automatically. So the only real question is how much you would save due to equivalence of permutations of the other pieces.

I did the same computation but reducing pawn symmetry on both sides the same way:
3: 524288 524288 100
4: 301465600 290979840 103
5: 92467625984 79135331668 116
6: 20567155539968 14305093222384 143
7: 3735559724230246 1947456033067182 191
8: 588698109703146693 213529294167604807 275
9: 83439994934544916195 19652448336691703337 424
10: 10887163846326643716271 1561065282681230985761 697
11: 1328958932314921409984354 109176580993481410741492 1217
12: 153546176647563470947658810 6824378818319881564216564 2249

[Leo]

I found this about 10 years ago.

Many show interest in what is to expect from 8-man endings. First, take note that the longest 6-man mate took 262 moves (KRN-KNN). Moving to 7-man endings doubled this value. Second, 8-man tablebases include much more endings with both sides having relatively equal strength. All this gives us a strong hope to discover a mate in more than 1000 moves in one of 8-man endgames. Unfortunately the size of 8-man tablebases will be 100 times larger than the size of 7-man tablebases. To fully compute them, one will need about 10 PB (10,000 TB) of disk space and 50 TB of RAM. Only the top 10 supercomputers can solve the 8-man problem in 2014. The first 1000-move mate is unlikely to be found until 2020 when a part of a TOP100 supercomputer may be allowed to be used for solving this task.

[Viz]

I think 8-man can give 0-5 elo gain like 7-man. No practical benefit. Only academic interest. I don't use even 6-man. If there is interesting position I check DTM from Shredderchess .

You are wrong.
With current technology 8 man will lose elo because they will slow down engine a lot during probing because of their enormous size.

[syzygy]

Well, at least I don't see any point in spending half the effort to do something half.

That is already a really weird attitude; half the job done without introducing any loss of efficiency should be considered a good start.

It is not doing half the job. It is doing the job half.

It becomes an even more counter-productive stance when you apply it to doing, say, 99% of the job for 1% of the effort. Especially if the remaining 1% concerns only cases that no one is interested in.

I am fine with doing 99% of the job. I don't care for doing the whole job with 99% correctness.

Your pi metaphor sucks. You should have said "no point in calculating the first 12 digits of pi when you cannot calculate the next million digits". Engineers would not agree...

But I did not say that, as you noticed. My pi metaphor was spot on.

Calculating the first 12 digits of pi as a first step towards calculating the first trillion digits is like calculating the 3/4/5-piece tables as a first step towards calculating the 8-piece tables. It is a necessary step. It is also necessary to do it with 100% accuracy. There is no point in approximately getting 99.99% of the 5-piece tables right "at half the effort". There is no point in getting 11 of the first 12 or 999 of the first 1000 digits of pi right.

Correctly calculating a well-defined subset of the 8-men tables, for example all positions with blocked pawns, could certainly be potentially worth the effort. Approximately calculating the value of 8-men tables, on the other hand, seems silly to me (unless you do it to solve a specific position or to solve some other problem, and if you have determined that your approximation will do for that specific purpose -- as I already wrote).

Now it would be nice if your next reply would not twist my words just so that you can pretend to outsmart me. Note that I am not twisting your words. So be better. Thx.

[syzygy]

I found this about 10 years ago.

Many show interest in what is to expect from 8-man endings. First, take note that the longest 6-man mate took 262 moves (KRN-KNN). Moving to 7-man endings doubled this value. Second, 8-man tablebases include much more endings with both sides having relatively equal strength. All this gives us a strong hope to discover a mate in more than 1000 moves in one of 8-man endgames. Unfortunately the size of 8-man tablebases will be 100 times larger than the size of 7-man tablebases. To fully compute them, one will need about 10 PB (10,000 TB) of disk space and 50 TB of RAM. Only the top 10 supercomputers can solve the 8-man problem in 2014. The first 1000-move mate is unlikely to be found until 2020 when a part of a TOP100 supercomputer may be allowed to be used for solving this task.

The idea that the longest mate must double with every extra piece (as someone has "predicted" in a paper) is really based on nothing.

I believe most pawnless candidates for longest mates have already been computed, and the longest mate record was increased only by a bit. See here:
https://en.chessbase.com/post/8-piece-e ... -interview
[pgn][Event ""]
[White "W + 584"]
[Black ""]
[Site ""]
[Round ""]
[Annotator "Marc Bourzutschky"]
[Result "*"]
[Date "2022.05.07"]
[PlyCount "600"]
[Setup "1"]
[FEN "R7/8/8/8/7q/2K1B2p/7P/2Bk4 w - - 0 1"]

{A new record position where White needs at least 584 moves to achieve
checkmate or transition to a won 7-man ending. This ending was checked with
two independent programs. The original result was obtained with Marc
Bourzutschky's general 8-man generator, the 2nd result from Yakov Konoval's
7-man generator, modified to handle the special situation of 8-man endings
withone pair of blocked pawns. Play near the end of the winning line may look
a little strange, because in the DTC metric the algorithm prefers positions
where Black loses the queen in N+1 moves to positions where he loses his pawn
in N moves. That does not affect the overall correctness of the line.} 1. Rf8 Qe1+ 2. Kb3 Qh1 3. Rd8+ Ke1 4. Bf4 Qb7+ 5. Kc3 Qc6+ 6. Kd3 Qg6+ 7. Ke3 Qb6+ 8. Rd4 Qb3+ 9. Rd3 Qb6+ 10. Ke4 Qb1 11. Kd4 Qb4+ 12. Ke5 Qe7+ 13. Kd5 Qd8+ 14. Kc4 Qc8+ 15. Kd4 Qd7+ 16. Kc3 Qc6+ 17. Kb2 Qb6+ 18. Rb3 Qd4+ 19. Rc3 Qb4+ 20. Kc2 Qa4+ 21. Kd3 Qd7+ 22. Ke4 Qb7+ 23. Kd4 Qd7+ 24. Kc5 Qc8+ 25. Kb4 Qb7+ 26. Ka3 Qe7+ 27. Ka2 Qa7+ 28. Kb2 Qb6+ 29. Ka1 Qa7+ 30. Ba3 Qd4 31. Bg3+ Kd2 32. Bc1+ Kd1 33. Bb2 Qa7+ 34. Ra3 Qg1 35. Kb1 Kd2+ 36. Ka2 Qf1 37. Bc3+ Kc2 38. Bce1 Qc4+ 39. Ka1 Qb5 40. Rc3+ Kd1 41. Ka2 Qa6+ 42. Kb2 Qb5+ 43. Rb3 Qe2+ 44. Ka3 Qa6+ 45. Kb4 Qb7+ 46. Ka4 Qc6+ 47. Rb5 Qc2+ 48. Ka5 Qa2+ 49. Kb6 Qe6+ 50. Kb7 Qf7+ 51. Ka6 Qe6+ 52. Rb6 Qc4+ 53. Kb7 Qf7+ 54. Kc6 Qe6+ 55. Kb5 Qf5+ 56. Kb4 Qe4+ 57. Ka5 Qa8+ 58. Kb5 Qd5+ 59. Ka4 Qa2+ 60. Kb4 Qb1+ 61. Kc5 Qf5+ 62. Kd4 Qg4+ 63. Kc3 Qf3+ 64. Kb2 Qe2+ 65. Ka1 Qc4 66. Rb4 Qc6 67. Kb2 Qc1+ 68. Kb3 Qc2+ 69. Ka3 Qc1+ 70. Ka4 Qc6+ 71. Ka5 Qc5+ 72. Ka6 Qc6+ 73. Ka7 Qc5+ 74. Kb7 Qd5+ 75. Kb6 Qe6+ 76. Kc5 Qc8+ 77. Kd4 Qg4+ 78. Ke3 Qc4 79. Rb8 Qc5+ 80. Ke4 Qe7+ 81. Kd5 Qf7+ 82. Kc5 Qf5+ 83. Kb6 Qe6+ 84. Ka5 Qd5+ 85. Ka4 Qc6+ 86. Ka3 Qf3+ 87. Rb3 Qa8+ 88. Kb2 Qa6 89. Bb4 Qe2+ 90. Ka1 Qa6+ 91. Ba3 Qa4 92. Rb1+ Ke2 93. Bgd6 Qd4+ 94. Rb2+ Kd3 95. Bdc5 Qe4 96. Rf2 Qe1+ 97. Ka2 Qe6+ 98. Kb2 Qe5+ 99. Kb1 Qe1+ 100. Bc1 Qe4 101. B5e3 Kc4+ 102. Ka2 Qe5 103. Bf4 Qd5 104. Rc2+ Kd3+ 105. Kb1 Qb7+ 106. Rb2 Qe4 107. Rd2+ Kc3+ 108. Ka1 Qe1 109. Rb2 Kd3 110. Rb3+ Kc2 111. Rb5 Qf1 112. Rb2+ Kc3 113. Bfd2+ Kd3 114. Kb1 Kd4 115. Rc2 Kd5 116. Bb4 Ke4 117. Rd2 Kf5 118. Bd6 Ke4 119. Bg3 Qb5+ 120. Bb2 Ke3 121. Rc2 Qf1+ 122. Bc1+ Kd4 123. Ka2 Qa6+ 124. Ba3 Kd3 125. Rc7 Qe6+ 126. Kb1 Qb3+ 127. Bb2 Qb5 128. Rc2 Ke3 129. Be1 Qa4 130. Bbc3 Qb3+ 131. Kc1 Qa3+ 132. Rb2 Ke4 133. Kc2 Qa4+ 134. Kd2 Qd7+ 135. Kc1 Qc6 136. Rc2 Qa8 137. Ba5 Kf3 138. Bec3 Qa6 139. Rd2 Qa7 140. Bcb4 Qg1+ 141. Kb2 Qg7+ 142. Ka3 Qa1+ 143. Kb3 Qb1+ 144. Ka4 Qe4 145. Bd8 Qe8+ 146. Kb3 Qe6+ 147. Kc3 Qc6+ 148. Kb2 Qb5 149. Kb3 Qc6 150. Rd3+ Ke4 151. Rd6 Qe8 152. Rd2 Qe6+ 153. Kc3 Qc8+ 154. Kb2 Qb8 155. Bde7 Qh8+ 156. Kc2 Qc8+ 157. Bbc5 Qa6 158. Bed6 Qc4+ 159. Kb2 Kf5 160. Rd4 Qb5+ 161. Kc3 Qa5+ 162. Kb3 Qb5+ 163. Bb4 Kg6 164. Rc4 Qd5 165. Bbc5 Kf7 166. Kb4 Qb7+ 167. Ka5 Qa8+ 168. Kb6 Qd8+ 169. Bc7 Qf6+ 170. Ka5 Qc6 171. Bf4 Qa8+ 172. Kb4 Qb7+ 173. Kc3 Qa8 174. Bce3 Qa1+ 175. Kd3 Qb1+ 176. Kd4 Qb2+ 177. Ke4 Qb7+ 178. Ke5 Qe7+ 179. Kd4 Qf6+ 180. Kc5 Kg6 181. Kb5 Qb2+ 182. Rb4 Qg7 183. Bc5 Qb7+ 184. Ka5 Qc8 185. Bfd6 Qd8+ 186. Ka6 Qa8+ 187. Kb6 Qd8+ 188. Ka7 Qc8 189. Rb7 Qc6 190. Kb8 Qe8+ 191. Kc7 Qf7+ 192. Kb6 Qb3+ 193. Bb4 Qe3+ 194. Ka5 Qg5+ 195. Bbc5 Qd2+ 196. Kb6 Qb2+ 197. Kc7 Qf6 198. Rb4 Qf7+ 199. Kb6 Qe8 200. Rf4 Qd8+ 201. Bc7 Qd2 202. Rf2 Qc3 203. B7d6 Qb3+ 204. Kc7 Qc3 205. Rf4 Qa5+ 206. Kd7 Qb5+ 207. Kd8 Qc6 208. Rg4+ Kf7 209. Rg3 Qa8+ 210. Kc7 Qa5+ 211. Bb6 Qh5 212. Bbc5 Qh7 213. Be7 Qf5 214. Bf8 Qe5+ 215. Bfd6 Qh5 216. Re3 Qf5 217. Re5 Qg4 218. Re7+ Kg6 219. Re3 Qf5 220. Be5 Qf7+ 221. Kb6 Qf5 222. Bcd6 Qf2 223. Bd4 Qf5 224. Re7 Qc2 225. Rg7+ Kf5 226. B4e5 Ke4 227. Re7 Qc4 228. Rh7 Kd5 229. Rh6 Qc6+ 230. Ka7 Qb5 231. Bc7 Ke4 232. Bed6 Qa4+ 233. Kb7 Qb5+ 234. Bb6 Qd5+ 235. Kc8 Qc6+ 236. Bbc7 Qe8+ 237. Bd8 Qc6+ 238. Kb8 Kf5 239. Rf6+ Kg4 240. B8c7 Qe8+ 241. Kb7 Kh5 242. Bf4 Qd7 243. Bg3 Qe8 244. Bgd6 Qd7 245. Kb6 Kg5 246. Rf3 Kg4 247. Rf8 Qe6 248. Kb7 Qd7 249. Be5 Qe7 250. Rf6 Qd7 251. Kb6 Qd3 252. Bcd6 Qc2 253. Rf4+ Kh5 254. Rf8 Kg4 255. Be7 Qe2 256. B5d6 Qd3 257. Rf4+ Kh5 258. Kc7 Qb5 259. Bf6 Qd3 260. Kd7 Qb5+ 261. Kd8 Qb6+ 262. Bc7 Qe3 263. Be7 Kg6 264. Ke8 Qb3 265. Kf8 Qc3 266. Rf6+ Kh7 267. Bed8 Qb4+ 268. Bd6 Qd4 269. B8e7 Qc3 270. Rf4 Qh8+ 271. Kf7 Qg8+ 272. Kf6 Qg6+ 273. Ke5 Qc2 274. Ke6 Kg6 275. Rg4+ Kh5 276. Rg3 Qc4+ 277. Kf6 Qf1+ 278. Kg7 Qa1+ 279. Kf7 Qa2+ 280. Kf6 Qf2+ 281. Kg7 Qd4+ 282. Kg8 Qd5+ 283. Kh8 Qa8+ 284. Rg8 Qa1+ 285. Rg7 Qd4 286. Bg3 Qd7 287. Bf8 Qc8 288. Rg8 Qd7 289. Bg7 Qf5 290. Rf8 Qe6 291. Bf4 Qe7 292. Rf5+ Kg4 293. Rf6 Qd8+ 294. Kh7 Kh5 295. Rh6+ Kg4 296. Bd6 Qd7 297. Kg8 Qc8+ 298. Bgf8 Qc4+ 299. Kg7 Qd4+ 300. Rf6 Kh5 {301. Bf4 Qd7 302. Kg8 Qe8 303. Rh6 Kg4 304. Bd6
Qa8 305. Rf6 Kh5 306. Kh8 Qa1 307. Bfe7 Qb2 308. Bf4 Qd4 309. Kg8 Qd5 310. Kg7
Qg2 311. Bg3 Qb2 312. Bed6 Qb7 313. Bc7 Qb2 314. Bgf4 Qd4 315. Bcd6 Qb2 316.
Bb8 Qb7 317. Bbc7 Qg2 318. Kf8 Qa8 319. Bb8 Qa3 320. Kf7 Qb3 321. Re6 Kg4 322.
Kf6 Qc3 323. Bbe5 Qd3 324. Ke7 Qa3 325. Ke8 Qa8 326. Bb8 Qb7 327. Bbc7 Qb5 328.
Ke7 Qc5 329. Bcd6 Qf5 330. Bde5 Qc2 331. Rf6 Kh5 332. Rh6 Kg4 333. Kf7 Qd3 334.
Rd6 Qh7 335. Kf8 Kf3 336. Rh6 Qd7 337. Rg6 Qd8 338. Kf7 Qd7 339. Kf6 Qd8 340.
Ke6 Qe8 341. Kf5 Qf7 342. Kg5 Kg2 343. Rg7 Qf8 344. Kh4 Kh1 345. Rd7 Qa3 346.
Rd2 Qb3 347. Bd6 Qe6 348. Kg5 Qg8 349. Kf6 Qh7 350. Ke5 Qh8 351. Ke4 Qe8 352.
Kd4 Qb5 353. Rc2 Qb6 354. Kd3 Qb1 355. Kd2 Qb3 356. Bfe5 Qd5 357. Ke3 Qf7 358.
Rc3 Qa7 359. Ke4 Qb7 360. Kd4 Qa7 361. Kd5 Qa8 362. Kc5 Qa6 363. Bc7 Qa7 364.
Bb6 Qa8 365. Re3 Qa6 366. Kc6 Qa4 367. Kc7 Qc4 368. Kb7 Qd5 369. Ka6 Qe6 370.
Kb5 Qd7 371. Kb4 Qd2 372. Kc4 Qc2 373. Kb5 Qb1 374. Kc6 Qg6 375. Kb7 Qf7 376.
Bbc7 Qd5 377. Kb6 Qd2 378. Re4 Qd3 379. Rb4 Qe3 380. Kb5 Qf3 381. Bed6 Qb7 382.
Kc5 Qa6 383. Rb1 Kg2 384. Rb3 Qa7 385. Bb6 Qa2 386. Rc3 Qa4 387. Re3 Kh1 388.
Re5 Kg2 389. Kd5 Qa8 390. Ke6 Qe8 391. Kf6 Qh8 392. Kf7 Qh7 393. Ke8 Qg8 394.
Kd7 Qg4 395. Kc7 Qg7 396. Kc6 Qg4 397. Re3 Qc8 398. Kb5 Qd7 399. Kc5! Kh1 400.
Ra3 Qg4 401. Bbc7 Qg1 402. Kb5 Qg7 403. Ka5 Qd7 404. Kb6 Qe6 405. Rf3 Qh6 406.
Rb3 Qe6 407. Ra3 Qh6 408. Kb7 Qh5 409. Bb6 Qd5 410. Kc7! Qf7 411. Kc6 Qe8 412.
Kb7 Qf7 413. Ka6 Qc4 414. Ka7 Qf7 415. Bdc7 Qd7 416. Ra1 Kg2 417. Rg1 Kf3 418.
Rg3 Ke2 419. Ra3 Qh7 420. Re3 Kf1 421. Rf3 Kg2 422. Rg3 Kf1 423. Rg4 Qd7 424.
Rd4 Qb5 425. Rd2 Qa4 426. Kb8 Qe8 427. Bd8 Qe6 428. Rf2 Ke1 429. Rf4 Qd5 430.
Bdc7 Qg8 431. Ka7 Qg7 432. Rh4 Qd7 433. Rd4 Qe7 434. Kb8 Qe8 435. Rd8 Qb5 436.
Rh8 Qb3 437. Bg3 Kd2 438. Rd8 Ke2 439. Re8 Kd1 440. Bc7 Kd2 441. Re5 Kd1 442.
Re3 Qg8 443. Kb7 Qd5 444. Ka6 Qa8 445. Kb5 Qd5 446. Kb4 Qd2 447. Kc4 Qa2 448.
Kc5 Qc2 449. Kb5 Qb2 450. Ka6 Qa2 451. Ba5 Qc4 452. Ka7 Qd4 453. Bab6 Qd7 454.
Kb8 Kc2 455. Re5 Qg4 456. Bd6 Qd7 457. Bbc7 Kd3 458. Bc5 Qg4 459. B7d6 Qd7 460.
Re3 Kc4 461. Re7 Qd8 462. Kb7 Kd3 463. Kc6 Qc8 464. Kb5 Qf5 465. Re3 Kd2 466.
Kc6 Qc8 467. Kd5 Qf5 468. Kd4 Qg4 469. Ke5 Kd1 470. Kf6 Qh4 471. Kf7 Qh5 472.
Ke7 Qg4 473. Rd3 Kc2 474. Rg3 Qe2 475. Re3! Qg4 476. Kd8 Qg8 477. Re8 Qg5 478.
Kc7 Qh6 479. Be3 Qg6 480. Re5 Kd3 481. Bg5 Qf7 482. Bge7 Qa2 483. Rg5 Ke2 484.
Kd8 Qf7 485. Rg1 Qh5 486. Rg3 Kf1 487. Bf6 Qf7 488. Bd4 Qc4 489. Rg4 Qe6 490.
Rf4 Ke2 491. B6e5 Kd3 492. Rf6 Qg8 493. Ke7 Qh7 494. Rf7 Qh4 495. Bf6 Qe4 496.
Bde5 Ke2 497. Rg7 Kf1 498. Rg5 Qb7 499. Kf8 Qh7 500. Be7 Kf2 501. Ke8 Kf3 502.
B7f6 Kf2 503. Bd4 Kf3 504. Kf8 Qc7 505. Bde5 Qd7 506. Be7 Qe6 507. B5d6 Kf2
508. Bc5 Ke2 509. Kg7 Qd7 510. Bd6 Kf1 511. Kf7 Qc6 512. Be5 Qh6 513. B7f6 Qh7
514. Bg7 Qe4 515. Bf8 Qd3 516. Kg7 Qd7 517. Kh6 Qe6 518. Kh7 Qc4 519. Kg7 Qc6
520. Bfd6 Qa4 521. Rg3 Qa7 522. Kh6 Qa2 523. Rg4 Qd5 524. Rg5 Qc6 525. Rg6 Qc1
526. Kg7 Qe3 527. Bf6 Qa7 528. Kh6 Qe3 529. Kh7 Qa7 530. Rg7 Qe3 531. Bde5 Qd2
532. Rg5 Qf2 533. Kg7 Qd2 534. Kh6 Qe2 535. Rg6 Qd1 536. Rg7 Qf3 537. Rg3 Qf5
538. Rg5 Qe4 539. Bd4 Qh4 540. Kg7 Qf4 541. Rg1 Ke2 542. Bfe5 Qf5 543. Kh6 Qf8
544. Kg5 Qe7 545. Bf6 Qd6 546. Bde5 Qd2 547. Kh5 Qd7 548. Kh4 Qh7 549. Kg5!
Qg8 550. Bg7! Qd8 551. Kh5 Qg8 552. Bd4 Qf7 553. Kg4 Qg6 554. Kh4 Qh7 555. Kg5
Qg8 556. Rg3 Qd8 557. Kh5 Qc8 558. Bge5 Qf5 559. Rg5 Qe4 560. Rg7 Qf5 561. Kh4
Kf1 562. Rg1 Ke2 563. Rg5 Qh7 564. Kg4 Qe7 565. Rg7 Qe6 566. Kh4 Qf5 567. Rc7
Kf1 568. Rc1 Ke2 569. Rc3 Qh7 570. Kg4 Qd7 571. Kg3 Qh7 572. Bf6 Qh6 573. Bde5
Kf1 574. Rf3 Ke2 575. Rf2 Kd1 576. Bd4 Ke1 577. Bc3 Kd1 578. Kg4 Qe3 579. Rd2
Kc1 580. Bg5 Qe6 581. Kh4 Kb1 582. Rb2 Ka1 583. Re2 Kb1 584. Re6}[/pgn]
Mate in 584. It seems the forum's pgn viewer stops at 300 moves.

[hgm]

Well, at least I don't see any point in spending half the effort to do something half.

That is already a really weird attitude; half the job done without introducing any loss of efficiency should be considered a good start.

It is not doing half the job. It is doing the job half.

It becomes an even more counter-productive stance when you apply it to doing, say, 99% of the job for 1% of the effort. Especially if the remaining 1% concerns only cases that no one is interested in.

I am fine with doing 99% of the job. I don't care for doing the whole job with 99% correctness.

Your pi metaphor sucks. You should have said "no point in calculating the first 12 digits of pi when you cannot calculate the next million digits". Engineers would not agree...

But I did not say that, as you noticed. My pi metaphor was spot on.

Calculating the first 12 digits of pi as a first step towards calculating the first trillion digits is like calculating the 3/4/5-piece tables as a first step towards calculating the 8-piece tables. It is a necessary step. It is also necessary to do it with 100% accuracy. There is no point in approximately getting 99.99% of the 5-piece tables right "at half the effort". There is no point in getting 11 of the first 12 or 999 of the first 1000 digits of pi right.

Correctly calculating a well-defined subset of the 8-men tables, for example all positions with blocked pawns, could certainly be potentially worth the effort. Approximately calculating the value of 8-men tables, on the other hand, seems silly to me (unless you do it to solve a specific position or to solve some other problem, and if you have determined that your approximation will do for that specific purpose -- as I already wrote).

Now it would be nice if your next reply would not twist my words just so that you can pretend to outsmart me. Note that I am not twisting your words. So be better. Thx.

But you are still arguing from the misconception that there would be anything wrong with the correctness of the part that was calculated. Which makes everything you say nonsensical and irrelevant. It's like insisting alpha-beta is no good because you only searched small part of the tree, so that this part must be mostly incorrect.

[syzygy]

But you are still arguing from the misconception that there would be anything wrong with the correctness of the part that was calculated. Which makes everything you say nonsensical and irrelevant. It's like insisting alpha-beta is no good because you only searched small part of the tree, so that this part must be mostly incorrect.

Are you referring to this post, which is about "usually you will get the correct result" x 10?
viewtopic.php?p=968448#p968448

[hgm]

Apparently not, because I cannot find the word 'correct' in that posting at all...

The point is that in a generally won end-game most P-slices can be solved as total wins even under rules where opponent promotion is an immediate loss, because in practice you won't be able to beat that extra Queen. Only the small fraction of P-slices for which this is not the case you won't be able to solve.

Another way of looking at it, is that instead of a WDL bitbase, one could use a WUL bitbase, where U means 'undefined'. A probing engine would then have to search on when it hits a U position. And guess what, they are already doing that when they hit a D position. So not much changes for the user. Only some of the W or L would now be a U too. Mostly for positions that a game would never reach, such as multiple Pawns on the pre-promotion rank for both sides.