| View previous topic :: View next topic |
| Author |
Message |
storm_norm
Joined: 18 Oct 2007
Posts: 1741
|
 Posted: Sun Mar 02, 2008 11:01 am Post subject: March 2 bundle |
 |
|
these were posted on sudoku.org.uk
#966
| Code: | +-------+-------+-------+
| . 7 . | . 2 . | . . . |
| 2 . . | . . 7 | 8 . . |
| . . . | 4 . . | . . 2 |
+-------+-------+-------+
| . . . | . . 4 | . 6 9 |
| . . 3 | . 8 . | 7 . . |
| 5 1 . | 9 . . | . . . |
+-------+-------+-------+
| 9 . . | . . 3 | . . . |
| . . 6 | 5 . . | . . . |
| . 2 . | . 9 . | . 4 . |
+-------+-------+-------+ |
=================
weekly extreme # 75
| Code: | +-------+-------+-------+
| . . . | . 6 8 | . . . |
| . 2 . | 7 . 9 | . 1 . |
| . . 1 | . . . | . . 4 |
+-------+-------+-------+
| . 5 7 | 6 . . | . 9 . |
| 2 . . | . 8 . | . . 1 |
| . 1 . | . . 7 | 5 4 . |
+-------+-------+-------+
| 5 . . | . . . | 4 . . |
| . 9 . | 5 . 6 | . 3 . |
| . . . | 4 7 . | . . . |
+-------+-------+-------+ SE 8.4 |
================
daily telegraph-Feb 29
| Code: | +-------+-------+-------+
| . . 8 | . . 1 | 9 . . |
| . . . | 4 . . | . 5 . |
| . . . | . 3 . | 8 . 6 |
+-------+-------+-------+
| . 5 2 | . . . | 7 9 . |
| . . . | 1 . 3 | . . . |
| . 6 3 | . . . | 2 4 . |
+-------+-------+-------+
| 3 . 4 | . 7 . | . . . |
| . 8 . | . . 5 | . . . |
| . . 6 | 9 . . | 3 . . |
+-------+-------+-------+ |
================
the opening moves to the extreme are an x-wing then an xy-wing... then??
the telegraph is a one stepper.
Last edited by storm_norm on Mon Mar 03, 2008 5:40 am; edited 1 time in total |
|
| Back to top |
|
 |
Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
|
| Posted: Sun Mar 02, 2008 4:28 pm Post subject: |
|
|
| Norm, I know the first two puzzles are the Friday and Sunday diabolicals that I still refer to as Mepham, even though he's gone. Is the extreme from the same source, one level harder than the diabolical? |
|
| Back to top |
|
|
Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
|
| Posted: Sun Mar 02, 2008 6:41 pm Post subject: |
|
|
| Quote: | | the opening moves to the extreme are an x-wing then an xy-wing... then?? |
After that I eliminated one candidate to break up a deadly pattern. Then a couple of iterations of extended Medusa and that did it. |
|
| Back to top |
|
|
storm_norm
Joined: 18 Oct 2007
Posts: 1741
|
| Posted: Sun Mar 02, 2008 8:16 pm Post subject: |
|
|
marty,
I am not exactly sure of all the details, but it looks like Andrew Stuart has been leading the way for that site to hold these competitions. and from what I have been reading, he has several competition puzzles going on all the time, including the daily and the weekly extremes. so I am assuming that Andrew Stuart is the one coming up with the puzzles. |
|
| Back to top |
|
|
keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
|
|
| Back to top |
|
|
storm_norm
Joined: 18 Oct 2007
Posts: 1741
|
| Posted: Mon Mar 03, 2008 5:39 am Post subject: |
|
|
oops, ok, I will take it out. |
|
| Back to top |
|
|
keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
|
| Posted: Mon Mar 03, 2008 6:45 am Post subject: |
|
|
| storm_norm wrote: | | oops, ok, I will take it out. |
No need to do that. Just so people have the cross-reference.
Keith |
|
| Back to top |
|
|
Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
|
| Posted: Tue Mar 04, 2008 10:46 am Post subject: |
|
|
I had encountered this "Extreme" puzzle before it was posted here and solved it exactly as Marty described above. However, this posting prompted me to revisit it and see what I could do if I avoided any use of extended Medusa. It made for a nice study in AICs. Those wishing to explore AICs might want to follow along. (I don't claim this is the most elegant solution. But, I found it interesting.) I number the steps in brackets, for those keeping count.
After basics plus: [1] the X-Wing on <8> in c28; [2] the XY Wing with r6c9 pivot that removes <7> from r7c8; and [3] the r79c38 {26} UR that removes <2> from r9c8, we have:
| Code: |
+-----------------+-------+------------------+
| 3479 347 3459 | 1 6 8 | 2379 257 23579 |
| 368 2 3568 | 7 4 9 | 368 1 3568 |
| 679 678 1 | 3 5 2 | 679 678 4 |
+-----------------+-------+------------------+
| 38 5 7 | 6 1 4 | 238 9 238 |
| 2 346 346 | 9 8 5 | 367 67 1 |
| 689 1 689 | 2 3 7 | 5 4 68 |
+-----------------+-------+------------------+
| 5 367 236 | 8 9 1 | 4 26 267 |
| 1478 9 48 | 5 2 6 | 178 3 78 |
| 16 68 26 | 4 7 3 | 1269 568 2569 |
+-----------------+-------+------------------+
|
[4] I started by looking for exploitable ALSs and quickly noticed an interesting possiblity in the middle floor that led to a nice branched AIC:
| Code: |
({67})r5c78=(3)r5c7
/ \
(8)r2c9-(8=9)r6c9 (3={68})r2c17-(8)r2c9; r2c9<>8
\ /
(6={89})r6c13-(8=3)r4c1
|
Notice how the two branches knock out the two <3>s in the {368} ALS in r2.
[5] Note that the 2 <8>s in r4 of b6, considered as a group, are strongly linked with the <8> in r6c9. We can exploit this in a chain:
(3)r5c3-(3=8)r4c1-(8)r4c13=(8)r6c9-(8=7)r8c9-(7)r7c9=(7-3)r7c2=(3)r7c3-(3)r5c3; r5c3<>3
[6] We have now exposed a {468} XY Wing, pivot r8c3, that removes <6> from r5c2 and r79c3.
The grid now:
| Code: |
+----------------+-------+------------------+
| 3479 34 459 | 1 6 8 | 2379 257 23579 |
| 368 2 568 | 7 4 9 | 368 1 356 |
| 679 678 1 | 3 5 2 | 679 678 4 |
+----------------+-------+------------------+
| 38 5 7 | 6 1 4 | 238 9 238 |
| 2 34 46 | 9 8 5 | 367 67 1 |
| 689 1 689 | 2 3 7 | 5 4 68 |
+----------------+-------+------------------+
| 5 67 3 | 8 9 1 | 4 26 267 |
| 1478 9 48 | 5 2 6 | 178 3 78 |
| 16 68 2 | 4 7 3 | 169 568 569 |
+----------------+-------+------------------+
|
[7] There is now an AIC that exploits some strong links in <8>, <4> and <3> with a couple of bivalues along the way. Some Medusa multi-coloring helped me find it.
(3-8)r2c7=(8)r3c8-(8=8)r9c28-(8=4)r8c3-(4)r5c3=(4-3)r5c2=(3)r5c7-(3)r2c7; r2c7<>3
[8] This exposes a {68} W-Wing in b37, based on the strongly linked <8>s in c8, that removes <6> from r9c7.
[9] It also exposes an otherwise useless XYZ Wing in r2c7|r35c8. We can transport the <6>s in r35c8 to r79c9 (by grouped strong links). This eliminates <6> from r2c9. (NOTE: I don't believe that this step is necessary for the solution. However, I included it because it is not an AIC and is interesting.)
[10] With <3> gone from r2c7, we have another AIC (which Medusa multi-coloring could find):
(8-5)r2c3=(5-3)r2c9=(3)r2c1-(3)r4c1=(3-4)r5c2=(4)r5c3-(4=8)r8c3-(8)r2c3; r2c3<>8
[11] Now that r2c3 is a {56} bivalue, we can exploit it in another AIC:
(5)r1c3-(5=6)r2c3-(6=8)r2c7-(8)r3c8=(8-5)r9c8=(5)r1c8-(5)r1c3; r1c3<>5
The grid now:
| Code: |
+----------------+-------+---------------+
| 3479 34 49 | 1 6 8 | 279 257 59 |
| 68 2 5 | 7 4 9 | 68 1 3 |
| 679 678 1 | 3 5 2 | 679 678 4 |
+----------------+-------+---------------+
| 38 5 7 | 6 1 4 | 238 9 28 |
| 2 34 46 | 9 8 5 | 367 67 1 |
| 689 1 689 | 2 3 7 | 5 4 68 |
+----------------+-------+---------------+
| 5 67 3 | 8 9 1 | 4 26 267 |
| 1478 9 48 | 5 2 6 | 178 3 78 |
| 16 68 2 | 4 7 3 | 19 568 59 |
+----------------+-------+---------------+
|
[12] There is another otherwise useless XYZ Wing in r2c1|r37c2. We can transport the <6>s in r37c2 to r9c1, thus removing <6> from r36c1. Notice that a naked quad in b1 now removes <7> from r3c2, resulting in some more simplification:
| Code: |
+---------------+-------+--------------+
| 3479 34 49 | 1 6 8 | 279 257 59 |
| 68 2 5 | 7 4 9 | 68 1 3 |
| 79 68 1 | 3 5 2 | 679 678 4 |
+---------------+-------+--------------+
| 38 5 7 | 6 1 4 | 238 9 28 |
| 2 34 46 | 9 8 5 | 367 67 1 |
| 89 1 689 | 2 3 7 | 5 4 68 |
+---------------+-------+--------------+
| 5 7 3 | 8 9 1 | 4 26 26 |
| 148 9 48 | 5 2 6 | 18 3 7 |
| 16 68 2 | 4 7 3 | 19 58 59 |
+---------------+-------+--------------+
|
[13] Next is an XY Chain, from r2c7 via b1, c2, r9 and b9 to r8c7. Or, perhaps more elegantly, it can be seen as a {68} remote pair, r2c7 and r9c2, extended by the <8> strong link in b9. In either case, it removes <8> from r4c7.
[14] Unless someone can see something I cannot, we need one more AIC:
(8)r68c1-(8=6)r2c1-(6)r3c2=(6-8)r9c2=(8-5)r9c8=(5-2)r1c8=(2)r1c7-(2=3)r4c7-(3=8)r4c1-(8)r68c1; r68c1<>8
This solves the puzzle. |
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
