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# Tough Sudoku for 15/August/2009

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 Great shot, Sue! It would make a terrific 2000-piecer! 15/Aug/09 12:08 AM "Down by the old Mill Stream..." 15/Aug/09 12:13 AM Just beautiful!!!! The water is so calm! 15/Aug/09 12:18 AM Tranquil place. Have a terrific weekend, everyone! 15/Aug/09 1:44 AM 22:32 Maen! Took my time... seemed like a pretty easy Tough today. Thanks for starting the song, Shiela! Good old tune! 15/Aug/09 1:53 AM Dear Steve, Thank you for your tip that the Aug 1 Tough would be an instructive puzzle to follow to learn about loops. It sure was, and I thank you Alfred and Sotir for your solutions that helped illuminate it all. However, I am left with one problem I can’t figure. You all say, More... 15/Aug/09 2:31 AM Slow - 43:07 15/Aug/09 3:32 AM Hmmmm... Wonder if they grind grits there? 15/Aug/09 5:30 AM Hi Brenda.Because of pairs 69 at b13 and 68 at gi3,the only place left for 6 in row 6 is at a6.This gets you to UP39.Regards,Alfred. 15/Aug/09 8:33 AM Argh-gh-gh-gh ! I had made the eliminations and it was right there staring at me, jumping up and down, waving its little hands ! Thanks so much,Alfred ! Mn-m-m, nobody has posted yet. Do we have an interesting one here? Brenda 15/Aug/09 8:48 AM I got to UP 40 today,but no further yet.Will have another go later in the day. 15/Aug/09 10:25 AM Aug 15 .au er 7.3 Again, I did not fully optimize this path.1) start 23 UP 272) (LC2)bc3 => ef3<>2 UP 353) (NP45)g37 => g268<>45 UP 404a) (HP47)df2 => df2<>354b) (HP49)df8 => df8<>1354c) (HP68)e46 = (8)e3 - (8=5)i3 - (5)ef3 = (5)e2 => More... 15/Aug/09 1:20 PM Brenda, You are most welcome! 15/Aug/09 1:32 PM 20:52, I got a little stuck in the middle. Hi everyone. 15/Aug/09 3:23 PM Hi Steve.I followed your proof to step 5),UP51.But in step 6,can't h8 still =1 (as well as 3 or 6) ? BTW,small typo in step 4d).Shouldn't it read 7(f6)? Regards,Alfred. 15/Aug/09 7:31 PM This is my try for today. 1)up27 - locked set on 2 - up402)locked 5 in i23 =>i56<>53)swordfish on 6 c468e46g68=>a48h8hi6,h4<>64)(3)e2=e8-d9=i9=>i2<>35)(1)i5=(1)i9-(1=3)h8-(3)e8 More... More... 15/Aug/09 7:56 PM Hi Neil.Some ideas on your solution:I think your notation in step6 breaks down after 8 at i3,but I can see your logic.In "english";after i9=1,h8=3,later i2=5,i3=8,i1=3,i6=9.So i5=16.Maybe you don't need step 5,as step 6 seems to encompass step 5.I couldn't see the 2 extra UPs after More... 15/Aug/09 10:48 PM Agree with Judy. Suitable extended (to the right?) this would make a nice large jigsaw puzzle. 15/Aug/09 10:55 PM Hi Alfred,Indeed, lots of careless typos in my solution.4d.) (7)f6 = c6 - c8 = (7-5)a8 = e8 - e23 = f3 => f6<>5 UP 41 6) Wwing: (6=3)g8 - h8 =h1 - (3=6)i1 => i9<>6 UP 81 I do have a tendency to make dyslexic type typos, and often cannot find them even after More... 16/Aug/09 10:04 AM Hi Neil, 6) One could use brackets to represent the memory of the chain already traversing that area. The following is not exactly the same chain, but works similarly, using the almost XWing with candidate 3:(9=3)i4 - (XW3)ei19 = (3) h1 - (3=1)h8 - (1)i9 = (1)i5 => i5<>9 16/Aug/09 10:25 AM Alfred and Steve, Many thanks for your elucifdations. Best regards, Neil 16/Aug/09 3:49 PM Hi Alfred, After the 9 is eliminated in i5, there is a hidden pair 29 in df5, so excluding 9 from d4, therefore c4=9 and e4=6. Best regards, NeilPS: Please excuse my typo in my previous thank-you note. 16/Aug/09 5:24 PM 39:52 22/Aug/09 7:37 AM SE=7.3 09/Sep/10 11:17 PM