Sudoku's are really simple for computers. Simply map them to an Exact Cover and then solve the Exact Cover by reduction. Never takes more than a few seconds, even for the most hard ones. This is because Sudoku's have one solution and I have never come across a Sudoku that has one solution and cannot be solved by simple logic reasoning. There do exist Exact Covers that have one solution, but require guessing. But even if some Sudoku would require some guessing, it still cannot be a complex problem, and a back-tracking algorithm would solve it quickly. See Hardest Sudoku for some more details, algorithms and such.

It is easy to define a Soduku with more than one solution. Just take a Soduko and remove some hints. Great chance it will now have multiple solutions.

It's okay. Sadly, with Alzheimer's Disease progress is always negative. There is no cure and also no hope for improvements. Of course, patients varry from day to day, so sometimes you can be fooled in believing that there is progress, but in the long run this is not the case. Alzheimer's Disease is a fatal disease with an average life span of about ten years after it has been diagnosed. My wife was diagnosed based on abnormal protein levels in the brain fluid (through epidural), which at that time, 2006, was still experimental, but is now believed to be one of the most accurate methods available. At that time was 49 years old and thus is a rare case of Early Onset Alzheimer's Disease. Most often Alzheimer's Disease is a greater burden for the caretakers (family members) than the patient itself. Although the prognoses is very bad, it does not mean that is no longer can be happy.

URU in the Myst sequel of games has been open sourced by Cyan Worlds. See openuru.org.

With neuro-degenrative disorders (dementia) it is not the case that all brain cells die at once. Even with people who have progressed far, still have brain with living brain cells. The brain cells that are left can form new connections. Maybe the magnetic stimulation can improve the communication between the brain cells that are left. In the past decades several medicines have developed that stimulate the production of certain neurotransmitters with the same effect. However, most of these medicines only work with a few people and the effect is mostly not very dramatic. The problem is that all these things do not cure or even halt the neuro-degenerative process. It might be a breakthrough in the research but it is definitely not a breakthrough in the cure of such disorders. But any method that can elevate the simptoms is nevertheless important because for the suffers of these diseases and their caretakers.

My wife, when in the process of being diagnosed with Alzheimers, reported that her thinking was much clearer after she had got an MRI scan. The effect lasted only half a day. I reported this to her neurologist, who said that it was nonsense. But what I have read here, it looks like that what she reported was real. This was in the fall of 2012. In the mean time she has progressed a lot and I wonder if stimulation would have any benefit now.

According to my exact cover program (which required only logic reductions to solve the puzzle) this sudoku can be solved without having to make any guess.

My program for converting a Sudoku to an exact cover took 0,015 second. My program for solving an exact cover took 0,031 seconds. This time is including producing 23K output file containing log and result. This mainly due to the fact that the exact cover can be solved with only applying logic reductions, taking two columns and see if there an implication. If this is the case, all rows that do not contain a 1 value in both columns can be removed. This results in 60 rows giving the solution to the sudoku, one row for each empty position.

If you convert this Sudoku to an exact cover problem, it can be solved by logic reduction alone. An exact cover solver that I wrote took 0.031 seconds to do this (including generating output for each reduction it made). Exact cover problems are in NP-complete, but a Sudoku that can be solved with logic reasoning alone, can always be solved with only logic reductions.

I don't really understand what is the idea of announcing that you are going to make a very important announcement without saying anything about the contents of the announcement while almost everybody can guess what the announcement is going to be about. They are doing this over and over again. Why not simply state: Yes we have found good evidence for the existence of the Higgs bosom and tomorrow we are going to share the results in detail. In that way the general public knows all it needs to know and the scientist can queitly study the proof after the initial exictment is over.

When (long ago) my father was diagnosed with cancer, he nor my mother was informed about this (we are talking 40 years ago) because the doctors thought my mother could not deal with it and my father would die anyway. Somehow, my father recovered from the cancer (don't ask me how). However, for many years my parents encountered problems when they wanted to change their healt insurance, because the health insurance company knew (from the bills that they paid) exactly what was going on with my father.

I am getting the impression that the SAT score correlates rather strong with Verbal intelligence. While the type of puzzles, which I answered correctly within a second, are very much depending on non-verbal (performal/visual) intelligence. I think this is true for many of the Slashdot readers. But on the other hand, I have to agree, I often see intelligent people (especially those who are strong on verbal skils) make thinking errors like the one mentioned in the article, and I also often caught myself making these kind of mistakes, while I am rather strong non-verbal thinker. I guess that my experience with debugging has learned me to think things through and not rely on the first answer that pops up in my mind. I also have come to the realisation that real thinking is hard and requires effort. But it is also a fact that many intelligent people stumble on problems like the Monty Hall puzzle, and that some of those cannot be convinced of the correct answer. I have come to the conclusion that some people with a PhD degree are lacking the non-verbal intelligence required to understand a problem like the Monty Hall puzzle, which sometimes frustrates me.

I noticed that all the authors are Chinese. You would almost get the impression that research (in hard sciences) in the USA has been taken over by Chinese.

Yes, almost like claiming that you have violated the copyrights by copying the words "to be" from the works of Shakespear.

Aside from the fact that it is a linear problem to solve (simple polynomial if you add lens correction), you also need a good feature extractor to create a 3D model from a set of 2D pictures. There are some excellent packages for doing 3D reconstruction, but they also come with a high price tag. There are some free implementations as well, but they are not very good.

Is seems to be an interesting solver, but you have to add a lot more for building an application for 3D reconstruction. I wonder if Google is going to release the software behind PhotoTour as well. And preferable for Windows.