Effect of Adding Almost-Locked Set Analysis --------------------------------------------- solver: Sudoku Assistant data source: http://magictour.free.fr/top1465 synopsis: All told, in the solutions of the 1465 puzzles in this collection, 2115 marks were eliminated using almost- locked set analysis. The 40 puzzles listed showed improved solution when basic almost-locked set analysis was included. In each case, the first line is without almost-locked set analysis; the second line is with. (This basic analysis includes checking to see if there are marks that are common to two almost-locked sets that are already weakly linked, allowing for the elimination of those marks.) For 14 of these puzzles, adding almost-locked set analysis allowed solution without resort to basic "trial and error" (P). These cases probably have something like an XYZ-Wing that the almost-locked set analysis found. 3D Medusa cannot find that sort of configuration. In all other cases, one type of weak-link analysis (3D Medusa) has been replaced by another (almost-locked set analysis). To load a puzzle into Sudoku Assistant: 1. go to http://www.stolaf.edu/people/hansonr/sudoku 2. click on "Number Block Input" 3. click on "load all 1465" 4. select the puzzle from the selection box that appears Methods used (in order of necessity): cross-hatch scanning (looking for singles; required) range checking (locked candidates) row/cell/block subset elimination A: almost-locked sets analysis (basic only) W: grid (weak cycle) analysis (X-wings, Swordfish, etc.) M: 3D Medusa chain analysis -- strong+weak P: hypothesis and disproof (trial and error) puzzle #clues #tidbits methods #W #M #P #steps ------------------------------------------------------ 12 18 423 MP 3 3 53 12 18 423 A M 3 48 16 18 422 MP 4 2 51 16 18 422 A M 2 45 44 18 417 M 1 52 44 18 417 A 52 47 18 420 M 2 53 47 18 420 A 52 64 18 421 M 3 45 64 18 421 A 47 73 18 420 M 1 48 73 18 420 A 48 75 18 420 M 3 50 75 18 420 A 51 83 18 419 M 2 50 83 18 419 A 49 86 18 420 M 1 45 86 18 420 A 44 94 22 468 M 1 32 94 22 468 A 33 97 18 419 M 3 55 97 18 419 A 52 129 18 422 W2MP 2 6 1 46 129 18 422 A W4M 2 5 47 150 18 422 M 1 51 150 18 422 A 51 155 18 420 M 3 50 155 18 420 A 49 163 18 416 M 2 52 163 18 416 A 51 206 18 415 M 1 50 206 18 415 A 50 226 18 424 M 1 45 226 18 424 A 44 300 19 449 M 2 46 300 19 449 A 42 307 19 449 M 1 42 307 19 449 A 42 405 17 405 W2MP 2 5 1 47 405 17 405 A W2M 1 1 46 512 21 460 MP 8 2 48 512 21 460 A M 11 52 533 22 463 W2M 1 1 32 533 22 463 A W2 1 37 598 24 480 W2 P 2 1 34 598 24 480 A W5 2 33 613 24 487 W2MP 1 4 1 38 613 24 487 A W4M 1 6 41 701 23 473 M 2 32 701 23 473 A 32 848 23 476 W3MP 1 2 1 42 848 23 476 A W3M 2 2 51 906 23 474 W2MP 1 2 1 45 906 23 474 A W5M 2 2 48 1080 21 462 M 1 32 1080 21 462 A 37 1136 23 479 MP 15 1 42 1136 23 479 A M 20 47 1245 24 480 MP 14 2 44 1245 24 480 A M 3 32 1249 23 471 MP 2 2 31 1249 23 471 A M 2 32 1257 24 491 W2M 1 3 32 1257 24 491 A W2 1 31 1306 21 456 M 1 42 1306 21 456 A 41 1321 23 472 W2M 2 1 28 1321 23 472 A W2 2 30 1358 22 472 W2M 1 1 29 1358 22 472 A 31 1365 24 480 P 2 30 1365 24 480 A 28 1386 23 468 W2MP 1 3 1 31 1386 23 468 A W5M 1 3 31 1407 17 408 M 1 42 1407 17 408 A 42 1454 24 472 M 1 22 1454 24 472 A 24 1464 24 475 M 1 30 1464 24 475 A 29