TABOO Strategy That Makes Hard Sudoku Easy

[@SmartHobbies]

Join the Smartie Party now 🥳to get EXCLUSIVE reward puzzle packs, ad free content, discord access, and so much more👉👉www.buymeacoffee.com/timberlakeB/membership Timestamps 0:00 Intro 00:19 It’s Solving Time 00:36 Puzzle Story 00:58 Finding Snyder Restrictions 02:12 BONUS Trick 05:49 BONUS Tip 07:31 Setting Up Taboo Strategy 10:35 Taboo Strategy Revealed 13:35 Solving Green Cell

[@kennethmiu691]

Thank you for the video! I learned a new trick from it which is the idea that within the 579 in the two cells in box 7, there must be a 7 in one of these two cells, thereby eliminating any other 7 in the box. Nice!

[@SmartHobbies]

Glad you liked the tip and learned something from it, Kenneth.

[@richardcranium0]

If I were solving for time in a tournament (I've never entered one nor am I likely to), I'll use Uniqueness and just go with whatever result it gives me, whether that's an elimination(s) or a digit. What I like to do instead is, for example a BUG +1, I know what the one cell is but don't place that digit, I find some other way (there's almost always another way) to place that digit - kites, Skyscraper, chains, etc. Builds on techniques I already know and (hopefully!) keeps me sharp.

[@SmartHobbies]

That makes perfect sense. It is quite satisfying to solve with one of the other strategies. Do you ever solve puzzles for time?

[@nayfen5767]

you forgot to eliminate the 7 in r3c3 with the UR, even though you said it's applicable in all sectors that see the UR. Here, the elimin comes with the clean up, but it's not always the case

[@SmartHobbies]

Thank you for pointing that out, and you are absolutely right. The elimination goes up the column as well. 💪🏻

[@laszloliptak611]

Nice puzzle. Solved it in 13:55. At the end one can also find a chain to finish solving the puzzle without using the uniqueness trick: r6c4(68)-r7c4(85)-r7c3(53)-r3c3(37)-r3c2(78)-r3c7(89)-r3c6(96), showing that either r6c4 or r3c6 must be 6, so we can eliminate 6 from r6c6. Regarding the avoidance of the uniqueness trick: It is kind of a "meta" information to use, of course only works if the puzzle only has one solution. Not using it is kind of a "hard" mode, where we not only find a solution, but logically prove that there is no other.

[@SmartHobbies]

You make a great point, Laszlo. Thank you for sharing.

[@jonbrowne]

I should have spotted that as I was aware of the technique!

[@SmartHobbies]

It seems so obvious after it gets pointed out, right, Jon?

[@jonbrowne]

Yes indeed Timberlake!

[@Ramakrishnagm]

I solved quickly, and saw your vedio after the same UR 59,59,579,579 in row 8,9., that is the easy to find, I got the same elimination. Nice puzzle thanks.

[@SmartHobbies]

Glad you liked it! Nice job finding the UR.

[@AnonimityAssured]

I thought I might have found a different UR, as the cell you highlighted seemed to play no significant role. Just for fun, I left that cell till last (63 = row 6 column 3): 63, 55, 42, 41, 17, 95, 18, 11, 65, 15, 14, 45, 86, 47, 69, 68, 78, 88 (hidden pair in box), 28, 38, 73 (UR, boxes 7 and 9), 71, 21, 81, 22, 23, 82, 72, 87, 77, 74, 92, 66, 64, 32, 33, 29, 39, 26, 24, 56, 54, 96, 84, 93, 83, 99, 89, 46, 44, 36, 37, 27. Ignoring the UR, there's another taboo strategy. A bit of virtual chaining quite quickly leads to a contradiction: R2C7 = 8 → R3C2 = 8 → R7C1 = 8 → R2C1 = 3 → R2C9 = 6 → R3C6 = 6 → R6C& = 8 → R7C4 = 8; a conflict. Or, R2C7 = 8 → R3C2 = 8 → R7C1 = 8 → R9C6 = 8 → R6C6 = 6 → R2C4 = 6 → R2C9 = 3 → R£C3 = 3 → R7C1 = 3; a conflict. Alternatively, I could have done a few more write-ins before applying a two-way chain: 81 instead of 73 (naked single), 22, 72, 87, 77, 23, 82, 92 (two-way chain from R6C6)*, 21, 71, … * If R6C6 = 6, then R2C4 =6, R2C9 = 3, R3C3 = 3, and R9C2 = 8. If R6C6 = 8, then, R7C4 = 8, and R9C2 = 8. HoDoKu suggests that XY-Chains are needed instead of the UR, but I can't see how they differ significantly from my virtual chains.

[@enjoyalaugh133]

Nice one. 9 mins. no pencil marks

[@SmartHobbies]

Nice job. How long have you been watching the channel?

[@jonbrowne]

Was stuck at the end and couldn’t find rectangle technique! Thanks Timberlake

[@SmartHobbies]

Glad you tried this one Jon. It’s great to see you in the chat again.

[@anaayoung9142]

You solved this one in a similar way you solved the last one. Using uniqueness. My time was 7:33. How I solved it: R3C6 is eitheir 6 or 9. If it is 6 then R3C2 is a 8 (because the logic in the row) making R7C1 a 8. At the same time R6C6 is a 8 and we can't place a 8 in box 8. I think this is right. Not sure 😅 Thanks for the solve! 🤗 Ps: after started to watch you, when I solve classic sudoku I try a bit more than I tried in the past, before I give up and search for help. Interesting right? (Hope this sentence make sense 😅)

[@SmartHobbies]

It does! It sounds like you have more confidence now and believe you can spot something you may not have before. I am so happy for you Ana! Keep it up. 👍🏻

[@iuriikononenko9238]

Don't like to use the UR. It is like circular reasoning - we use uniqueness to prove it has a unique solution. Even when the rule says there is only 1 solution, you can't be sure, if this is the true one solution, or considering uniqueness there is only one.

[@SmartHobbies]

You make a great point. Thank you for sharing. Do you avoid UR altogether in search of other strategies?