dailysudoku.com

[Brightangel]

I was stuck so I tried to get a hint but a message box came up stating I had either done it wrong or it was impossible. I restarted a couple of times in case I had gone wrong.
The next time I restarted I used the hint button each time till it gave me the message again. So unless the computer got it wrong I think it may just be impossible. Does anyone have a solution?

[Brightangel]

If at first you don't succeed.......Well I persevered and lo and behold I solved it. Maybe a xx in the system perhaps why I could not get a hint.

[Didona]

[Hasel]

Hey ,, even i was not able to complete that






Hasel

[TomT]

I just discovered the discussion list, though I've been solving dailysudoku.com Sudoki for a year or so. I needed to wind down after working all night to get a document finished. On my first try I ended up in a dead end, but this evening it worked out nicely.

When I first discovered Squigglies, I worked out two rules that I applied to each box in turn after doing a sweep to start with:

1) If a particular digit is restricted to just one row/column, then all occurrences of that digit in other boxes in the same row/column can be deleted as candidates.

2) If a particular digit can't be found in a particular row/column in any other box but this one, it has to occur in that row/column in this box and should be deleted from all other rows/columns in this box.

This was enough to solve a lot of puzzles, and often even the ones rated "Very Hard". However, I did get stuck sometimes -- a nasty puzzle last March held me for days. More recently I realized I could apply techniques I apply to ordinary sudoki also to Squigglies. Basically the first rule give above generalizes to this:

1a) If a particular digit is restricted to just N rows/columns in N boxes, then all occurrences of that digit in other boxes in the same row/column can be deleted as candidates.

N can be 2, 3, or theoretically even 4 in a particularly contorted Squiggly. Anyway, I find that with rule (1a) I can solve most Squigglies, and adding rule (2) takes care of the rest.

[Asellus]

Hi TomT. Welcome to the discussion board!

The rules you discuss are all various ways of expressing what is commonly known as Locked Candidates. You can find descriptions of this in various places online, such as here.

Locked Candidates, along with "Subsets" (such as Hidden/Naked Pairs/Triples/etc.) are considered to be "basic" techniques. So, when you see people refer to "after basics", they are referring to the state of a puzzle after these concepts have been applied.

If you are interested in "Squiggly" puzzles in particular, then you should read posts in this forum having to do with the "Law of Leftovers." That makes a big difference in solving "Squiggly" puzzles.

[TomT]

Thanks for the directions, Aselus. Interesting reading. I followed your further link to how you solve puzzles without pencilling, but I haven't had time to fully assimilate it yet.