Puzzle Description Suppressed:Click below to view spoilers

#1: Teresa K (fasstar) on Dec 31, 2009 [SPOILER]

Comment Suppressed:Click below to view spoilers

Comment Suppressed:Click below to view spoilers

Gator, I think resorted to edge logic when I got stuck. I know it is solvable without the edge logic, but I wasn't able to do it. I'll go back and try to figureout the line logic, but I'm not as good at finding those tricky clues as you are.

Adam, can you find the next clue?

Dot R22C33. But that really doesn't help.

I wanted to make a more difficult puzzle, but this is ridiculous. I really don't want people to agonize over this (unless they want to), so I am publishing an easier version of the same puzzle. (I made a slight alteration to the corners of the frame). But I am leaving this one up as is, just because it is such an enigma. The checker says it is logically solvable, so there must be a way.

I'll keep working at it. I just wanted to make sure I wasn't missing something obvious.

I was going to say the same thing about R22C33 as Teresa. I had forgotten 1 dot that you had placed, but I was at the same spot otherwise.

I finished solving this with edge logic (because I was stuck using line logic). I then cleared the screen and clicked helper. The computer couldn't solve it with line logic either. In fact, the computer was missing the black square in C21R24, and it was missing 4 dots in column 29, rows 21-24.

Nice puzzle, by the way.

Comment Suppressed:Click below to view spoilers

What a beautiful ornament. It was a little tricky to solve, but lots of fun. Thanks Teresa.

Thanks, Adam and Telly and Jewel. I gave up trying to solve it with just line logic. :-)

A tricky solve and a beautiful puzzle. Thanks, Teresa!

Gator asked in another item if pbnsolve could have been mistaken in calling this puzzle line solvable, so I checked it out. Starting from the image in Gator's response #2 above, pbnsolve sets the following cells:

R20C25 must be white (column clue contradiction).

R21C14 must be white (column clue contradiction).

R22C34 must be white (column clue contradiction).

After this you can do a bit more easy line solving (the helper button will do it) then it gets tricky again.

pbnsolve then finds the following:

R22C16 must be black (row clue contradiction).

R22C23 must be white (row clue contradiction).

R26C7 must be white (column clue contradiction).

From there the rest is easy. The helper can complete the puzzle.

So there are a couple cells along the way that are quite tricky to spot, but they are still one-line-at-a-time things.

In the picture I posted row 19 is already complete. So I'm not understanding where to start from your explanation.

Oops. The program uses zero-based indexes, and I forgot to translate them to one-based indexes. I've edited my previous comment to add one to each index.

Simply amazing. :D

Yeah, sometimes simple line solving isn't all that simple. Edge logic is sometimes the easy way to solve a puzzle.

So how come the computer can mark it as line logic solvable, but then can't solve it?

Two different programs. Checker and helper work differently.

I guess that makes sense. I figured they would run the same. I think helper is not that useful, since it misses a lot of things.

The helper is a tiny little program that runs in your browser. It's goal is to help out puzzle designers who have to repeatedly solve different versions of the same puzzle over and over again. It deliberately does only the easy parts for you, while giving you an chance to examine the tricky bits.

The checker is a fairly large and complex program that runs on the web server. It's designed to be a full autonomous solver. It's used to give puzzle designers instant feedback n whether their puzzle has multiple solutions and whether it is solvable with only line and color logic. I've open sourced it so you can get it from http://webpbn.com/pbnsolve.html . I've also done a lot of analysis of it, to compare it's performance to other nonogram solvers written by other people here http://webpbn.com/survey/ . It can solve most puzzles in less than a tenth of a second. There are only two puzzles on the site that take it more than two minutes.

Though the two solvers have some points of similarity, the helper is a Ford Pinto, and the checker is a Ford GT. (OK, I'm from SE Michigan).

Just out of curiosity, which 2 puzzles might those be?
And by the way, any thoughts on why I can't use the "L" key feature?

I messed up there. I was only counting black & white puzzles. The two black and white puzzles that it takes more than 2 minutes to solve are #6574, a really brilliant Gator puzzle, which takes 17 minutes, and #2556, a mess with a pile of multiple solutions. There are 6 color puzzles it takes more than 2 minutes on and I don't remember what they are.

It solves 98.5% of all puzzles in under a tenth of a second. On webpbn it automatically gets cut off after one second, since I don't want the whole website bogging down because the checker is analyzing a puzzle. I believe there are currently 17 puzzles in can't solve in a second.

Nonogram puzzle solving is known to be one of a class of hard problems known as "NP-complete" problems. They have the interesting property that if anyone managed to find a reliably fast algorithm to solve any one of them, then you could use variations of the same algorithm to solve all of them, and become instantly rich and famous, because it includes a huge number of problems of great practical importance. The checker is not going to make me rich and famous.

Great puzzle! I really enjoyed solving it and getting past the tricky bits. I didn't ever get stuck or frustrated, but I did use some edge logic. Really fun. :)

Thanks, Diana. That was quite an accomplishment to finish solving with logic. I think this is the most difficult one of my own that I have solved.

Quite beautiful! A lovely illustration of a memorial event. Very tough to solve because it was a little tedious; but no guessing.

I finally made it through with only line logic no hints!!! Teresa, I did agonize over it but only because I wanted! :)

After David's comment, I checked the comments. Then I HAD to resolve this one. I love the line logic in the puzzle.

Me too! There were a couple of dots that were SO satisfying to find! I didn't track my solve, but it was great fun!

Show: Spoilers

Goto next topic

You must register and log in to be able to participate in this discussion.