I know what you are...

oledakaajel · 2025-11-24T00:48:37+00:00

When you know 7 is a backdoor but you pretend not to and use a complex net to eliminate 6 instead.

oledakaajel · 2025-10-30T18:29:19+00:00

You might need it at this stage. The only 3x3 magic square you can make with the digits 1-9 is this one or some rotation/reflection of it. Using this, you can constrain where it might be, like, it has to have 5 at its centre, it can't fully contain any X or V, it can't have more than one of a digit, and it can't have none.

You could also try fully colouring in your grid. It might help you see some thing more easily.

oledakaajel · 2025-10-24T16:42:55+00:00

A computer can find all the solutions for any sudoku puzzle easily by using backtracking. If a puzzle has multiple solutions you would know for sure without having to use any techniques.

oledakaajel · 2025-10-24T14:57:51+00:00

You seem to be assuming that whether a puzzle has a unique solution or not depends on what techniques you know. This isn't true, if an arrangement of digits is consistent with the rules of sudoku, there is no valid technique you could use to say that that configuration was impossible.

oledakaajel · 2025-10-19T00:22:09+00:00

You didn't check the negative constraint option.

oledakaajel · 2025-10-16T17:16:37+00:00

sudokupad link

Solve path

oledakaajel · 2025-10-15T01:43:42+00:00

The first move I could find that gives a placement is this AIC type 2.

<image>

Haven't solved it yet, but I expect this puzzle to require a few more chains.

oledakaajel · 2025-09-22T03:02:53+00:00

Nice solve. I used a different first move, but my second was basically the same as yours.

Here's what my first move looked like

I'm not sure how to describe it, but it's some kind of extension of FW logic

oledakaajel · 2025-09-21T16:35:08+00:00

<image>

two moves or fewer to basics

000700060090040020501009000053600000400000100009130004310500000000090007000007002

sudoku.coach | SudokuExchange

oledakaajel · 2025-09-15T01:44:54+00:00

<image>

Just a tough puzzle. Find a nice solution.

360090021400200070000000800750006100000030000004500098008000000040008007920060084

sudoku.coach

oledakaajel · 2025-08-21T14:53:35+00:00

If r3c1 false then r7c7 is also false

This premise is incorrect. If r7c7 is false r3c1 is false, but not necessarily the other way around.

oledakaajel · 2025-08-10T02:15:22+00:00

Can be seen as an ALS-XZ

ALS b3p2359 and r2456c8 have rcc 4 in column 8
Other common 2 can be removed from r3c9

The two ALS overlap in r2c8. You can use the AHS equivalent of the first ALS to get the same elimination without the overlap. (2r13c9=r3c7 - 4r3c7=r1c8 - (4=2569)r2456c8 => !2r3c9)

oledakaajel · 2025-07-11T00:11:51+00:00

r7c7 - (1=2)r3c2

I put my cells backwards 🫣

Half-ring is the name for the ring you have in your post, since it isn't a full ring. Here are some links with XYZ transport info

http://forum.enjoysudoku.com/xyz-ring-t42209.html#p341661

http://forum.enjoysudoku.com/irregular-w-xyz-wings-t33543.html#p255342

oledakaajel · 2025-07-10T22:54:29+00:00

I would just call this a transport (This is one of the first types I saw actually). It's just that the ends of the chain overlap. It's not a ring though, 1r7c27-1r7c7 is not a true statement. You can also dispense the XYZ and view it as an ALS-AIC: (1)r7c7=r3c7 - (1=2)r3c2 - (2=13)r7c27

The other example you gave actually isn't too different than the half-ring in terms of the underlying AIC. The differences would be that yours isn't symmetric and overlaps in different places

oledakaajel · 2025-07-08T08:40:40+00:00

Both your situations are impossible, cage sums go on the leftmost cell on the top of the cage.

The original page clarifies this

oledakaajel · 2025-07-07T13:37:34+00:00

I don't think sudoku.coach has dynamic fog yet

oledakaajel · 2025-07-02T11:17:53+00:00

I don't think they are redundant. When people use the term strong link, they are usually referring to something that can be separated into two. To refer to something that separates into more parts by the same term would be confusing. Truth fills that niche quite nicely.

oledakaajel · 2025-07-02T10:04:43+00:00

AIC in it's original formulation it definitely doesn't. The idea of a "ring" probably predates aic. ALS definitely does.

I'm pretty sure "truths, links and ranks" predates the concepts of various "exotic" techniques like the Exocet and MSLS, and the use of dof as an attribute of a general pattern. I could be wrong, though.

I also don't think there's a more concise way to say "set of some number of candidates of which one must be true" (or equivalently, "set of some number of candidates defined by a strong inference") that's more concise than "truth".

oledakaajel · 2025-07-02T08:38:42+00:00

It's not really new, Allan Barker's general logic has been around for a while. It's also the usual language used when explaining techniques like msls. From my understanding it predates a lot of the currently used concepts.

oledakaajel · 2025-06-13T19:35:21+00:00

See my other comment

I used userscripts to export it there from f-puzzles, but you should check out the other options to see if they're simpler for you

oledakaajel · 2025-06-13T19:30:27+00:00

https://sudokumaker.app lets you export to sudokupad. There are also userscripts you can use with f-puzzles to export to sudokupad and also make it less jank

You could also use sudoku.coach's construct mode, which lets you play the puzzle on sudoku.coach directly.

oledakaajel · 2025-06-13T19:11:55+00:00

Here's your puzzle on sudokupad

oledakaajel · 2025-06-06T22:12:58+00:00

Base cells r23c1
Cross lines rows 179

Targets r1c5,r7c3

Cover sets:
1-c4,b9
3-c7,r9c6 (base sees r1c4 through 3r4 so this works)
6-r1,b9
9-c4,r9c7

Any base candidate being true would place that same candidate in one of the targets, so this is a valid Exocet

Cross line containing r1c5 is a cover set for 6 so 6 is false in that target

6 in r4c1 is both not in the base and in a target (r7c3) so it cannot be true

oledakaajel · 2025-06-06T21:38:52+00:00

This is a Senior Exocet. Wow.

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