Sudoku Players' Forum (clone)

Although it's worth noting that that guide - and much of the discussion in this forum - is geared towards solving 'advanced' puzzles, that is, ones which are much harder than puzzles that appear in books and newspapers, and which require very complex tactics that generally involve keeping meticlous "candidate lists" (or having a computer program to do it for you). For 'normal' sudoku solving, only the stuff before "For the addict" is really relevant, and that can be done (with a little practice) without much or any use of pencilmarks.

em wrote:The point I was actually trying to make, albeit unsuccessfully, was that I thought it was a little condescending of you to say that other people don’t understand Swordfish because you hadn’t seen a proof.

Thank you, Em for sharing your thoughts. You are right, I can't say other people don’t understand Swordfish because I haven't seen a proof. My question is, "Without a proof presented with its description, is a swordfish really that simple to understand for most people?". Whilst I am not expecting an answer to this question, the point remains that for any technique to be called logical, the logic behind that technique should be fully understood prior to its application. To gain such understanding, a technique should has been proven at least once. I surely don't disagree that some people don't need to see a proof to understand how a swordfish works.

Thank you Jeff - I know you were being helpful and my thoughts sound testy on re-reading. I was actually in an argumentative mood - just in case you don’t know that it was TIC and not intended to offend.

Jeff wrote:Angus, Nicely done. Your proof also explains why a swordfish can have a 322, 332 or 333 formation.

This can also be extended to the 222 formation.

For example:

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. . . | . . A | . . A
. . . | . . . | . . .
. . . | . . . | . . .
---------------------
A . . | . . . | . . A
. . . | . . . | . . .
. . . | . . . | . . .
---------------------
A . . | . . A | . . .
. . . | . . . | . . .
. . . | . . . | . . .

MCC wrote:This can also be extended to the 222 formation.

Thanks, MCC.

Thank you for all of your responses. My question came from being able to do easy and medium puzzles in the newspaper but I haven't been able to complete a hard one. The newspaper puzzle directed me to this site.

I think I understand the concepts and enjoy using logic so I don't know why I can't do a harder puzzle.

Is there a secret with pairs? Or is it just continuing to do the puzzle until you figure out which number goes where?

I have been learning Sukoku by doing the puzzles in the Total Jumbo Sudoku book by Michael Mepham. I have done all the easy ones and am now doing the medium ones. Is this a good approach in learning to do Sudoku?

Marie26

If you post the original grid and the position you've reached on a 'hard' puzzle you're working on, then we may be able to help you overcome your difficulties.

Marie26 wrote:I have been learning Sukoku by doing the puzzles in the Total Jumbo Sudoku book by Michael Mepham. I have done all the easy ones and am now doing the medium ones. Is this a good approach in learning to do Sudoku?

It's as good a way as any. There are no hard and fast rules to learning the game so whatever suits you is fine. For me, practice is the key. I'm not familiar (as far as I know, I could be using the techniques described on this Forum and elsewhere without being aware of it) with techniques or their names and I've never gotten further than Pappacom's Fiendish level - which suits me at the moment. I do at least one puzzle a day, on paper, and that suits me.

As MCC stated, post the puzzle you're stuck with and where you are stuck and someone will give you a hint. It's easier to do this than to list a lot of techniques, especially when it's so hard to grade different puzzles. What I mean by that is, what's Hard for Michael Mepham - no disrespect intended - may not be Hard for Pappocom and the techniques listed for Pappocom's Hard grade won't be any use to you.

I have noticed from my time here that mostly everybody gets stuck with one of their puzzles at one time or another and someone is always on hand to help out.

Post it like this :

Code: Select all

Copy & paste this grid into Word, (for example)

. . . | . . . | . . .
. . . | . . . | . . .
. . . | . . . | . . .
------+-------+------
. . . | . . . | . . .
. . . | . . . | . . .
. . . | . . . | . . .
------+-------+------
. . . | . . . | . . .
. . . | . . . | . . .
. . . | . . . | . . .

Replace relevant dots/periods with numbers and then paste that grid back into the forum embedded in "code" tags (which forces fixed width characters).


Just makes it easier to read. Code button is at the top of the screen when you press reply (ie, you copy and paste the above grid into Word, replace the dots with the numbers you have, then back in the Forum, click reply, press the Code button, copy and paste the grid with numbers and dots from Word back into the Forum, then press the Code button at the end of the grid, so that the grid is embedded into the code tags). It'll look like this on your reply, except that there will be some numbers on the grid (obviously!) :

Code: Select all

[code]. . . | . . . | . . .
. . . | . . . | . . .
. . . | . . . | . . .
------+-------+------
. . . | . . . | . . .
. . . | . . . | . . .
. . . | . . . | . . .
------+-------+------
. . . | . . . | . . .
. . . | . . . | . . .
. . . | . . . | . . .
[/code]

I hope that's clear!

Luna

Marie26 wrote:"....Is there a secret with pairs? Or is it just continuing to do the puzzle until you figure out which number goes where ..."

Hi again Marie,

Following on from Luna and MCC above I would add that there's no "secret" with "pairs" but you do need to fully understand what "naked" and "hidden" pairs mean as they are useful techniques for puzzle solving. These techniques (including 'singles' and 'triples') and 'Locked Candidates'(1) and (2) are aptly explained in the previous suggested link
http://www.angusj.com/sudoku/hints.php

Cec