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ANALYSIS OF THE FULL LIST OF 246 T&E(3) PUZZLES mentioned before:
http://forum.enjoysudoku.com/the-hardest-sudokus-new-thread-t6539-1190.htmlAs already reported (
http://forum.enjoysudoku.com/the-hardest-sudokus-new-thread-t6539-1200.html):
- all of these puzzles are precisely in T&E(W2, 2);
- 94 of them can be solved using only Subsets + Finned-Fish + the Tridagon elimination rule (defined in the first post of this thread);
- 117 can be solved using Subsets + Finned-Fish + the Tridagon elimination rule + Whips;
(In a few cases, the Tridagon elimination rule can only be applied after a few whip eliminations. )
- 35 have no tridagon elimination rule: 2 6 7 8 13 18 29 36 37 38 39 40 41 48 51 56 60 61 63 72 80 81 102 103 106 118 121 123 126 139 146 147 177 192 217
What about those 35?
33 of them can be solved using Subsets + Finned-Fish + Whips + Tridagon-Forcing-Whips involving relatively short partial-whips.
No puzzle in the list requires any Tridagon related pattern with more than:
- either any number of additional candidates in a single cell,
- or only two additional candidates in different cells.The two exceptions are: #63 and #123
As they behave similarly, I'll analyse only #63
Notice that both of them have Tridagon links and Tridagon-forcing-whip eliminations, so that they are not exceptions to the above remark. They are only exceptions to the capability of these Tridagon patterns to bring them down to (relatively simple) puzzles.
Notice also that they don't have the highest SER (11.6)
#63:
- Code: Select all
+-------+-------+-------+
! . . . ! . . . ! . . 1 !
! . . . ! . . . ! . 2 3 !
! . . . ! 2 4 5 ! 6 . . !
+-------+-------+-------+
! . . . ! 7 . 4 ! . . 5 !
! . . 5 ! . 8 2 ! 7 . 6 !
! . 7 . ! 5 6 . ! 8 . . !
+-------+-------+-------+
! . 8 7 ! 4 . . ! . 6 . !
! 4 6 . ! . . 7 ! . . . !
! 5 . 2 ! 6 . 8 ! . . . !
+-------+-------+-------+
........1.......23...2456.....7.4..5..5.827.6.7.56.8...874...6.46...7...5.26.8...;30
SER = 11.6
- Code: Select all
(solve-w-preferences
"........1.......23...2456.....7.4..5..5.827.6.7.56.8...874...6.46...7...5.26.8...;30"
TRIDAGONS
)
Resolution state after Singles and whips[1]:
+----------------------+----------------------+----------------------+
! 26789 2459 4689 ! 389 379 369 ! 459 45789 1 !
! 6789 459 4689 ! 189 179 169 ! 459 2 3 !
! 13789 139 1389 ! 2 4 5 ! 6 789 789 !
+----------------------+----------------------+----------------------+
! 123689 1239 13689 ! 7 139 4 ! 1239 139 5 !
! 139 1349 5 ! 139 8 2 ! 7 1349 6 !
! 1239 7 1349 ! 5 6 139 ! 8 1349 249 !
+----------------------+----------------------+----------------------+
! 139 8 7 ! 4 12359 139 ! 12359 6 29 !
! 4 6 139 ! 139 12359 7 ! 12359 13589 289 !
! 5 139 2 ! 6 139 8 ! 1349 13479 479 !
+----------------------+----------------------+----------------------+
188 candidates.
- Code: Select all
hidden-pairs-in-a-column: c5{n2 n5}{r7 r8} ==> r8c5≠9, r8c5≠3, r8c5≠1, r7c5≠9, r7c5≠3, r7c5≠1
hidden-pairs-in-a-row: r4{n6 n8}{c1 c3} ==> r4c3≠9, r4c3≠3, r4c3≠1, r4c1≠9, r4c1≠3, r4c1≠2, r4c1≠1
extended tridagon for digits 1, 3 and 9 in blocks:
b4, with cells: r4c2 (link cell), r6c3 (link cell), r5c1
b5, with cells: r4c5, r6c6, r5c4
b7, with cells: r9c2, r8c3, r7c1
b8, with cells: r9c5, r8c4, r7c6
==> tridagon-link[12](n2r4c2, n4r6c3)
tridagon-forcing-whip-elim[13] based on tridagon-link(n4r6c3, n2r4c2)
....for n4r6c3: -
....for n2r4c2: partial-whip[1]: r6n2{c1 c9} -
==> r6c9≠4
singles ==> r9c9=4, r9c8=7, r3c9=7, r8c9=8
whip[1]: c7n4{r2 .} ==> r1c8≠4
tridagon-forcing-whip-elim[18] based on tridagon-link(n4r6c3, n2r4c2)
....for n4r6c3: partial-whip[1]: r5n4{c2 c8} -
....for n2r4c2: partial-whip[5]: c1n2{r6 r1} - c1n7{r1 r2} - c1n6{r2 r4} - c1n8{r4 r3} - r3c8{n8 n9} -
==> r5c8≠9
- Code: Select all
Resolution state:
+-------------------+-------------------+-------------------+
! 26789 2459 4689 ! 389 379 369 ! 459 589 1 !
! 6789 459 4689 ! 189 179 169 ! 459 2 3 !
! 1389 139 1389 ! 2 4 5 ! 6 89 7 !
+-------------------+-------------------+-------------------+
! 68 1239 68 ! 7 139 4 ! 1239 139 5 !
! 139 1349 5 ! 139 8 2 ! 7 134 6 !
! 1239 7 1349 ! 5 6 139 ! 8 1349 29 !
+-------------------+-------------------+-------------------+
! 139 8 7 ! 4 25 139 ! 12359 6 29 !
! 4 6 139 ! 139 25 7 ! 12359 1359 8 !
! 5 139 2 ! 6 139 8 ! 139 7 4 !
+-------------------+-------------------+-------------------+
As I had restricted the max length of Tridagon-Forcing-Whips to 18, that's all we get with the TRIDAGONS preference space, before we start using whips.
However, if I set it to 20, there are long computations but no other elimination seems to appear.
- Code: Select all
whip[3]: c9n9{r6 r7} - r8n9{c8 c4} - r5n9{c4 .} ==> r6c3≠9
t-whip[6]: r6c9{n9 n2} - c1n2{r6 r1} - c1n7{r1 r2} - c1n6{r2 r4} - c1n8{r4 r3} - r3c8{n8 .} ==> r6c8≠9, r4c8≠9
hidden-pairs-in-a-block: b6{n2 n9}{r4c7 r6c9} ==> r4c7≠3, r4c7≠1
whip[1]: c7n1{r9 .} ==> r8c8≠1
whip[1]: c7n3{r9 .} ==> r8c8≠3
biv-chain[3]: r7n5{c5 c7} - r8c8{n5 n9} - r7c9{n9 n2} ==> r7c5≠2
naked-single ==> r7c5=5
naked-single ==> r8c5=2
PUZZLE 0 IS NOT SOLVED. 45 VALUES MISSING.
- Code: Select all
Final resolution state:
+-------------------+-------------------+-------------------+
! 26789 2459 4689 ! 389 379 369 ! 459 589 1 !
! 6789 459 4689 ! 189 179 169 ! 459 2 3 !
! 1389 139 1389 ! 2 4 5 ! 6 89 7 !
+-------------------+-------------------+-------------------+
! 68 1239 68 ! 7 139 4 ! 29 13 5 !
! 139 1349 5 ! 139 8 2 ! 7 134 6 !
! 1239 7 134 ! 5 6 139 ! 8 134 29 !
+-------------------+-------------------+-------------------+
! 139 8 7 ! 4 5 139 ! 1239 6 29 !
! 4 6 139 ! 139 2 7 ! 1359 59 8 !
! 5 139 2 ! 6 139 8 ! 139 7 4 !
+-------------------+-------------------+-------------------+
At this point, I applied gT&E(1), which allowed no more eliminations.
Conclusion: after applying Subsets + Finned Fish + gBraids + the above tridagon-forcing-whip-eliminations, puzzle #63 is not solved.
The final resolution state is indeed in B2B.
The Tridagon-Forcing-Whips were enough to simplify the puzzle form T&E(W2, 2) to T&E(W2, 1) but not enough to solve it.
A similar analysis is valid for puzzle #123.