#1: Ron Jacobson (shmily999) on Aug 23, 2010

thanks for the input to the first guess post.

Along that note, is there a way to check if guessing is required, besides trying to solve the puzzle? I know thre is the solvabilty (is that a word?) help when you check a puzzle, but is there a check for guessing?

Yes and no. If you use the "Check" button when you are creating a puzzle, it will tell you:
a) The puzzle is unique and can be solved with only line/color logic. (Does not require guessing.)
b) The puzzle has a unique solution, but it must be manually solved to see if it is logically solvable. (May or may not require guessing, but it will require an advanced technique if it is not guessing.)
c) The puzzle has multiple solutions. (Inherently requires guessing.)

So when starting out I would strive towards publishing puzzles that fall in a). As you learn the advanced techniques, you will be able to better manually solve your puzzles that fit in category b). Please (IMO) do not publish puzzles that fall in c).

The question mark symbols in the puzzle list are a good indication of the guessing and multiple solutions ratings of a puzzle
- dark red = multiple solutions and much guessing
- dark black = multiple solutions and some guessing
- light red = unique solution and much guessing
- light black = unique solution and some guessing
- no mark = unique solution and no guessing

You can search for any of these combinations on the Find Puzzles page using the solutions and guessing options. Newer puzzles won't be marked correctly until either Jan reviews them or enough people rate them.

I've always had an issue with what people call guessing on this site - to me there is a difference between a puzzle that is marked 'requires guessing' because it is difficult but still has a unique solution, and one that has multiple solutions.

Any puzzle with a unique solution is logically solvable - if that logic involves having to prove some squares can't be filled in by using a little trial and error (Jan's addition of an undo feature has made this process a little easier), then I still consider that logic and not guessing.

Bottom line for me is if a puzzle is marked as unique solution and requires guessing, then it's logically solvable but likely to be a challenge. These are the puzzles I look for when I'm in the mood for a workout.

The great thing about Jan's site is there is something for everyone, and the find puzzles page is a good place to search for what you're looking for.

My puzzle "WPC #71 - Friendly" has the light question mark next to it, which means some guessing. It solves with advanced techniques, no guess work involved here. How did this mark get there? Do I need to explain how to solve it logically so this mark does not appear? I am new here so please shed some light... :)

Jan or I will eventually get around to manually marking advanced puzzles as either solvable by logic or requires guessing if their is too much look ahead.

Gator or Jan, could you please look at puzzle #12131. It's solvable with logic alone but still has a "?". Thanks
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Thanks Gator for looking after the solvability of puzzles on the site!

Gator, you apparently have been very busy. I used to have 7 or 8 light questions marks...I had grown quite fond of them. Now I am down to one! :'(

Yep, pretty busy lately. I'm back to April 14th, 2012 and moving that backward when I can plus keeping up on having all of the new puzzles solved.

The new solver has must have cleared up some as well. All but one of mine with the light question marks were reclassified when the new ratings came online. None of them had the "webpbn robot" notification.

The only one left is http://webpbn.com/index.cgi?id=8099 And if Gator would be so kind, we now have a category for it.

Done. :)

I've been improving the solver steadily over many years, in a sort of competition with other solver designers, but have been forgetting to install the newer versions here. I finally did that to get the blot-solving version, and I suspect that it will solve quite a few puzzles that the old one wasn't able to get in the time allowed. However what matters more is that I reran the solver on every old puzzle to separate out the line-solvable and trivial puzzles, and I did this on a faster computer than the one that serves webpbn, without the usual 1-second time limit on solves.

Thank you. (Both.)

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