## creating puzzles with certain techniques

Programs which generate, solve, and analyze Sudoku puzzles

### creating puzzles with certain techniques

I have made a generator that uses hidden and naked singles, pairs and triples, x wings and generalised x wings and row/column elimination (if a candidate occurs in only one row in a given box then that candidate cannot occur in that row in another box. ). However many of the puzzles it generates require just hidden and naked singles, or pairs or row and column elimination. Of many puzzles it's produced only one has required triples and only one has required generalised x wings. Is there a way of ensuring a puzzle requires a given technique, or is it a matter of churning out loads of puzzles until you get one with the required spec.
ab

Posts: 451
Joined: 06 September 2005

There is no way really to ensure that you get a puzzle requiring what you want. Just keep generating and then filter.
eclark

Posts: 14
Joined: 26 January 2006

And even if you could -- you couldn't. A puzzle cannot require any specific tactic -- the solver is free to us other methods that you might feel are more complex or difficult than 'required'. Only if there were a specific set of heursitics allowed would it make sense to say that a puzzle requires this or that.
tso

Posts: 798
Joined: 22 June 2005

You can generate a "not so new" puzzle by shuffling rows, columns, and symbols of an old one. The new puzzle will require the same solving chain, but it will look different.
Anyway, I guess it's not funny at all.

On the other side, you can get a higher probability of generatig difficult puzzles this way: every time you have finished generating a puzzle, try removing every given. Surprisingly, it will be eventually solvable (with one unique solution) after removing givens (one or more) you added in early stages of creation. And it will often be more difficult.
comocomocomocomo

Posts: 2
Joined: 10 July 2006