Preferred clue patterns

jido · Posted: Fri Aug 17, 2007 7:33 pm Post subject: Preferred clue patterns

When chosing a mask for the clues to show, is it better to chose random clues or are there some patterns that sudoku players prefer?

Is there a difference between sudoku beginners, intermediate, advanced in that respect?

Thanks.

jido · Posted: Sat Aug 18, 2007 12:32 am Post subject:

After doing some reading around here, I think I should focus on "unavoidables".

Maybe beginners would like more than two clues per unavoidable, while intermediate or advanced players would want no more. Then use random positions (maybe shooting for aesthetics) for the rest.

What maximum size unavoidable should I be looking at? If I do not want too much processor use, is it enough to look at size up to 9, then count on statistics and hope bigger sets are covered?

I will not go more than size 11. In sudoku checker there are >400 sets of size 12.

wapati · Posted: Sat Aug 18, 2007 2:09 am Post subject:

At first I thought that you wondered about random spacing versus symmetry.

I now think that neither of us know what your question is.

Elucidate?

jido · Posted: Sat Aug 18, 2007 9:36 am Post subject:

No I was not thinking about random spacing versus symmetry. I was thinking of the patterns in a grid that appeal to sudoku players.

For example, a beginner would like the satisfaction to fill a line or a box fast, or find all the 4's in the grid (that's my level).

An intermediate player would like the challenge to have less clues, forcing him or her to scan all boxes, marking the cells with alternatives...

Finally the advanced player would simply want a grid that is not easily solvable with common techniques.

I think it is possible to generate the two first type of grid automatically by looking at the unavoidables and insert more or less clues in there according to the level.

The third type of grid (advanced) would require a solver and some heuristics, so I would probably not target that group. I can just include a "enter your own" puzzle type, where people can paste boards from other sources.

jido · Posted: Sun Aug 19, 2007 3:45 am Post subject:

Hey, can someone run this grid through checker?

I found only one unavoidable of size <= 6 in it

daj95376 · Posted: Sun Aug 19, 2007 6:26 am Post subject:

jido · Posted: Sun Aug 19, 2007 11:18 am Post subject:

Yeah, maybe it does require ~30 clues for a random grid. I found that 27 givens starting from a 25 and adding clues until sudokusolver solves it, then clearing the most obvious moves:

JPF · Posted: Sun Aug 19, 2007 5:05 pm Post subject:

Hi jido,
Your puzzles are nice but not minimal.
You can remove some givens and still have valid puzzles.
Here are some examples :

Puzzle 1
remove 4 givens :

jido · Posted: Sun Aug 19, 2007 6:02 pm Post subject:

Thanks!
Did you make the puzzles by hand, by program or find from a database?

I think I may have missed something important... Is this a size 4 unavoidable set?

JPF · Posted: Tue Aug 21, 2007 9:57 pm Post subject:

Well, my computer is becoming my right hand Smile

What kind of database could I use to find puzzles having a given solution ?

To answer your initial question, look at the techniques used by a solver.
If you don't have your own solver, see here.

JPF

Jean-Christophe · Posted: Wed Aug 22, 2007 9:02 am Post subject:

gsf · Posted: Wed Aug 22, 2007 4:12 pm Post subject:

JPF · Posted: Thu Aug 23, 2007 7:12 am Post subject:

Thanks gsf.

Your program is obviously not a database Smile

gsf · Posted: Thu Aug 23, 2007 6:15 pm Post subject:

jido · Posted: Mon Aug 27, 2007 3:10 pm Post subject:

This is exciting...

gsf, what is the meaning of the line starting with # after each result? For example: