I wasn't saying that all Sudoku's can be solved without back-tracking, I was just commenting about that its bad design to only guessing and back-tracking while there are other methods for finding a solution much faster. It is nice to note some improvements that could be made to the program, but missing the fact that a very poor performing algorithm is being used, is much worse. It is like correcting spelling mistakes in a mathematical proof while missing the fact that it has a logical error.

I have read stories that NASA considers to shutdown this rover mission due to budget cuts and priorities.

Most Sudoku's can be solved without back-tracking. There is a rather trivial mapping of Sudoku's to Exact Cover problems (see: Hardest Sudoku). Good solvers, only use back-tracking when needed, and try to apply logic reduction first. When there is a column were A implies B, all rows in which B is true and A false can be eliminated, because a selection of such a row will leave the A column empty. Most of the published Sudoku's can be solved with using this simple reduction rule.

I wonder if the the opportunity rover project will get an extra extension now, or that this very succesfull rover will be left alone, while still being functional.

Here in Europe radars remain essential because of Russian planes (both fighters and nuclear bombers) are flying around with their ADS-B switched of, just to test how quick European forces respond to possible treats. These planes fly in international air space, but often at close range of commercial flights. European countries are quite angry about this behavior, but the Russians think that they do nothing wrong. Just waiting for the first mid-air collision to happen. About a decade ago, the Russians started with these flights again, which they did during the Cold War. Especially, the last year they are become bolder and bolder, trying to enter national air space over and over again, and flying at supersonic speeds.

We only used branches for very long running project or after a release. All other work was simply done in our development branch. Keeping you changes local for a long time is no problem. I used to use update many times a day, always keeping up-to-date with the latest check-ins on the development branch and occasionally having to resolve a merge conflict. For really long running projects, I would create a patch at the end of the day and store it on a file server for back-up. Transfering changes from one branch (development) to another branch (for a bug-fix release) can simply be implemented by creating patches and apply these to the given branch. Which is not really much complicated than all the commands that you have to use in Git for some operations.

I am not denying that Git is more powerful than Subversion, but to me it seems much less user-unfriendly and less robust agains commonly made mistakes. I feel Git makes me think much more about what I have done, and is less forgiving for small mistakes, in that sense it often feels like a burden than a support.

And why then does it say in all kind of manuals that you should not use rebash unless you know what you are doing!

After using Git for about a year now, my conclusion is that subversion is good enough for your team, and heaven compared to Git. With subversion you can just peform an update without having to wonder if you might have something that still needs to be commited. I am also not convinced that creating branches and merging all the time is realy a good way of working for the team we are working in. I am getting used to stash, pull, stash pop, and resolve possible merge conflicts, and only commit and push when I am done with my changes. Yes, that sounds very much like working with Git in a subversion manner, but it seems to be the most productive way of working for us.

If you have come to this realization, I would consider you an expert. I think being an expert has not so much to do with your knowledge of the subject (the number of programming languages that you master, the number of libraries and/or frameworks that you know by heart) but your attitude toward the subject. Once you are aware of your strenghts and weaknesses with respect to the subject, you have become an expert.

Being an expert does not depend on what languages you master, it is having come to the understanding that programming is like writing and that you have to continue to develop your writing style, seeking out different ways of expressing yourself. It is all about knowing how to develop good interfaces (between different parts of your application and/or framework), how to separate concerns. But it is also about knowing when to stop, when to refactor something and when to just leave it like it is and implement a 'hack'. And also about realizing that developing software is often a team effort and coming to the realization that other members of your team have their own weaknesses and strenghts, and that it is all about finding trying to combine these with your own for the best achievable result, knowing that perfection is impossible in the imprefect world we live in.

I ride my bike almost every day, to work, to the city center and for doing shoppings. I try to bike as much as possible. I am too lazy to do sports, and biking is my way of doing exercises, which I find important having a job where I sit quiet most of the time. I am proud to live in the country with the (probably) best biking facilities in the world.

In fact in Chinese many words (characters) are pronounced in the same way and same tone, just like there are words in English that are pronounced in the same way, but written differently. Which meaning is intended is usually clear from the context. Tones often differ between dialect, and usually this is not a problem, not any more when English speakers from different dialects speak with each other. Furthermore, tones are restricted to the vowels, not to the sentences, as otherwise it would not be possible to sing in Chinese. The use of tones do not restrict you with respect to expressing emotions and there are just as many ways of saying hello in Chinese than there are in English.

I do not know whether Wikipedia counts as a reliable source, but it gives the same number: Chinese language and Languages of China. I also would not count Cantonees as a dialect of Mandrin. Cantonese has nine tones, where as Mandrin has only four, and most words are pronounced differently.

Some minorities are allowed to use their own language. I have been to a large city were many signs were written with Arabic characters.

In China, highschool is divided into junior secondary school and senior secondary school, both being three years. Only junior secondary school is compulsory. So, not all Chinese do attend highschool in the sense that they attend both junior and senior secondary school. In 2010 the percentage was 82.5. One should note that these percentages have increased strongly in the past two decades. To enter most higher education institutions it is not sufficient to finish senior secondary school, but one has to pass a state exam as well. I am aware that Chinese are obesessed with education, but it is also a fact that many Chinese still live in rural areas, where the quality of education is not always very high.

Fact is that most Chinese do not speak English, as I have experienced first hand. In fact 30% of the Chinese do not have Mandrin (including local dialects) as their first language: see this list of languages spoken in China. English is now taught at highschool, but not all Chinese do attend highschool. I have noticed that they are usually beter at reading the language than speaking it. I have met Chinese who published scientific papers in English, but could not keep a normal conversation.

Maybe the added weigh of obesity, will cause more force on our bones and compensate for the lack of it by moving less.

Spoiler alert for the movie Interstellar

It seems he did not get the main idea of the movie. The whole movie rests on the idea that it is possible to manipulate gravity in the past. The traversable wormhole was created by some humans in the far future and allowed the main character to communicate with the past, causing himself to join a space program, which would lead him to the place to communicate with the past, and by this save human kind from some disaster and in the far future allow to develop the technology to create the wormhole and a black hole with strange properties. So, it also involves a form of bootstrapping. Which makes even less sense, if indead traversable wormholes could be made at all.