On Perplexus, there is a link to the list of unsolved puzzles. But, as many visitors might find out, the list of unsolved puzzles is filled with lots of puzzles that have already been solved. We realize that this is due to the large number of puzzles which do not have official solutions posted.

For about a month, Journeymen and scholars have been working on a project to look through all the "unsolved puzzles" and sort through them. The main motivation behind this project was to expose those few puzzles that truly have not been solved. I initiated the project, but most of the credit goes to the people who helped: Dustin, Hugo, Gamer, brianjn, and Jer. We went through the whole list of "unsolved puzzles" and sorted them into various categories, beginning with 1-15-2004 puzzles and going all the way back.

This list is not a complete one. There are actually a few that have been particularly difficult to categorize, and they may join this list later. Also, this list does not include any puzzles posted more recently than "If you break me..." on 1-15-2004. The list is not necessarily up to date.
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The List of Truly Unsolved Puzzles:

Points On A Circle (in Geometry)
Posted on 2004-08-14 by ThoughtProvoker (No Solution Yet, 16 Comments)
Poker Hands (in Probability)
Posted on 2004-07-09 by Thalamus (No Solution Yet, 7 Comments)
Standing for higher powers (in Riddles)
Posted on 2005-12-31 by Enigma (No Solution Yet, 15 Comments)
The end of the game (in Numbers)
Posted on 2005-12-28 by Cory Taylor (No Solution Yet, 6 Comments)
Entangled code (in Cryptography)
Posted on 2005-12-25 by Tristan (No Solution Yet, 16 Comments)
Easily distinguished codes (in Numbers)
Posted on 2005-11-29 by Tristan (No Solution Yet, 7 Comments)
Next Numbers Please #6 (in Sequences)
Posted on 2005-09-09 by Brian Smith (No Solution Yet, 4 Comments)
Britannia Rul-ed The Waves Part 3 (in Sequences)
Posted on 2005-08-25 by sassy (No Solution Yet, 8 Comments)
Another Pattern of Numbers (in Numbers)
Posted on 2005-07-29 by Erik O. (No Solution Yet, 12 Comments)
Sequence of Letters (in Sequences)
Posted on 2005-07-15 by Dustin (No Solution Yet, 4 Comments)
Centrifugal Balance II (in General)
Posted on 2005-10-18 by Brian Smith (No Solution Yet, 25 Comments)
Pawns to stay put (in Games)
Posted on 2005-10-03 by Brian Smith (No Solution Yet, 13 Comments)
Word Meld 7 (in Word Problems)
Posted on 2005-01-22 by David Shin (No Solution Yet, 11 Comments)
Rummy Luck (in Probability)
Posted on 2005-01-07 by sassy (No Solution Yet, 9 Comments)
Splitting Heirs (in Shapes)
Posted on 2005-06-15 by Bryan (No Solution Yet, 8 Comments)
Rational sine (in Just Math)
Posted on 2005-05-02 by lmnop (No Solution Yet, 5 Comments)
Class Pass (in Probability)
Posted on 2004-06-24 by Gamer (No Solution Yet, 14 Comments)
Bird on a Wire (in Just Math)
Posted on 2004-06-07 by Sam (No Solution Yet, 39 Comments)
The Fifteen Steps (in Games)
Posted on 2004-04-26 by Gamer (No Solution Yet, 15 Comments)
(first part solution missing)
Chords and Chords (in Geometry)
Posted on 2004-03-24 by SilverKnight (No Solution Yet, 23 Comments)
Ten Colors (in General)
Posted on 2004-03-05 by Aaron (No Solution Yet, 6 Comments)
B-Palindromes (in Numbers)
Posted on 2004-02-25 by DJ (No Solution Yet, 7 Comments)
(solution in comments deemed as imcomplete)
Thirty two barbarians (in General)
Posted on 2004-01-28 by Gamer (No Solution Yet, 33 Comments)


Now let's hope none of my html went wrong with this post.

Congratulations and thankyou Tristan, Dustin, Hugo, Gamer, brianjn, and Jer. You have done a fantastic job on this project.
Now the challenge is on to all of the interested Perplexus faithful to try to "Solve the Unsolved." 23 and 13 to go ... and counting.
Readers are plentiful; thinkers are rare. - Harriet Martineau

I think The Highest Grade is unsolved in the general case; the specific numbers for that problem are solved.

If anyone has something to add to this list, or thinks that anything should be taken off (either because of an incorrect categorization or because of a recent solution) please say so here.

The conversing club 3, I gave a seating arragement and a method to construct it, which was what the problem asked for, so, what is missing?

Gamer himself sorted The conversing club 3, so you might want to ask him about it.

Oh, I thought it was unsolved and didn't want to go through the comments, can you give me a link to your comments?

That is pretty cool! I didn't know you could do that

Well, if you click on the "most commented on" search, the url contains all the information. It has a label, and then it lists all the pids of the problems that the search found. I just manipulate the url, and it gives any list I want. Apparently, this is something Levik had already programmed in so it could be used by his search link. He also did something similar with the "New replies" search. Neat, huh? Now if only I had thought of it before posting this list!

Ga

So it looks like you solved it, but the solution isn't understandable for someone who is just looking at it right now without reading the rest of the comments. Keep in mind that in a tough problem like this, the reason your method works is also important.

If you want to write the solution that is fine with me, but I would also be willing to write it or look at it too.

That's good, I just didn't want the solution to consist of a link to that thread. :)

Comments/solution added. Richard gave the pointer to the solution by way of links but I guess we want something more substantial.

As I said earlier, "The main motivation behind this project was to expose those few puzzles that truly have not been solved." The other motivation behind the project was so that we could post the official solutions to many problems that are ready for it.

There were several different categories for varying degrees of readiness for posting the official solution. Some don't have any official solution written yet. Some don't have complete official solutions. But some are ready to go this moment.

Starting Wednesday, I will start to post the official solutions of the puzzles in that last category. The solutions will be posted at the rate of 22 a week: 4 each weekday and 2 on Saturdays. This rate is subject to change.

Yes, this means that I will be posting the solutions to other author's problems, and that may include yours. If you have signed on recently, I will try to contact you if possible to warn you. But if you have an issue, you should contact me just in case. You may post your concern in this thread, or better yet, you can leave a note under the official solution. So that you have plenty of time to voice your concerns, I will start by posting the solutions of problems written by members that are no longer active.