I would also like (from time to time or in the books) puzzles like that 7x7 with negative numbers, but due to the really high level of difficulty (solver rating of 214, remember the discussion in the section Specific puzzles / your own puzzles, topic "The solution for a 7x7 special puzzle (-3 to 3)", this link viewtopic.php?f=16&t=99) it should be assigned with more than 16 points and obviously 3 or more days for the solution. Perhaps before going to that difficulty it would be interesting to get familiar with an intermediate one like an assymmetrical 6x6 (-3 to 2) or (-2 to 3).

Note that the size and difficulty level are not necessarily correlated: in other
words, I can easily generate a 7x7 puzzle with numbers [-3, ..., 3] that is quite easy.

Patrick

I think in the same way that it's the unfamiliarity with the new cages what makes the "apparent" more difficulty (probably no readjustments required ...).

But your observation suggests me a curiousity: Is the difficulty level "preadjusted" for every puzzle during the week?, for instance, in the case of the 9x9's, apart of the clearly more difficult on tuesdays, the other six during the week have each a particular difficulty level? or, in other words, are they different and preadjusted depending on the day of the week?. The 12x12's on thursdays and sundays have the same level or you make the sunday's a little more difficult (more free time )?. The "adjustable" parameter is the "solver rating" itself or simply the distribution of the cages/operators? (this links with the old discussion on the "a priori" or "a posteriori" solver rating).

The difficulty level is always in a range (solver rating range), which may be small or fairly large.
The range for the 9x9 on Tuesday is higher (i.e. the lower and upper limit are higher) than for
the other days of the week.

12x12 is the same on Thursday and on Sunday

The only reason I see why a 7x7 -3 to 3 puzzle should be more difficult than standard 7x7, is the existence of 0 which, in multiplication and division cages, makes some fields "any value". 7x7 with only sums and differences has exactly the same difficulty wheter it is 1-7, 0-6 -3 - 3 or 10-16.

Thank you, that clarifies the question.
And, in the case of tuesday's 9x9, it seems that having an "exact layout" (along with a high range of the solver rating) increases the difficulty. That's why I was wondering the other day (thread "cage shape" in "Specific puzzles / ... " if some type of layouts like the one for which I sent you the code, without individual cells, was going to be more difficult or not.

Solver rating is key. Here is a sample 9x9 with one of the Tuesday layouts, with a low solver rating:

(difficulty factor 51)

Thank you very much for this extra 9x9, you are right, very easy, very few minutes to solve it. An what about "the other side of the river?", would you be so kind of providing (when you have time) one of the most difficult 9x9's?, I assume in the range of 200 or more?. Something that requires 14 days or so to solve it ... .

The 9x9's (other than Tuesday's which are definately beyond my capabilities--I hate Mondays because these puzzles are so frustrating for me) have not only different cage shapes but fewer multiplication/division functions in the cages of late......for me, this makes it much harder as there are too many numbers that can add up to say 45 in an irregularly shaped cage than when you have to multiply/divide (which is why I have so much trouble with Tuesdays ).

Sorry for the ambiguity, but yes, I did mean 7x7 puzzles with possible cell values -3...+3. Thanks for considering it, Patrick. I'm glad to hear you can simply adjust the difficulty of the puzzles. Some of the ideas I've had have met with resistance from other members, and I want to make it clear I'm not pushing for "harder" puzzles, just "interesting" puzzles.

And as long as I'm posting, I have another suggestion. When I click on the number indicating the number of unread forum posts, I'd like to be taken straight to http://www.calcudoku.org/forum/search.php?search_id=unreadposts instead of the main forum page.