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Comment Interpretting instead of compiling (Score 2) 674

I once discovered that an interpretting parser was faster than a compiled version of it. Probably because the compiled version became so large that it was larger than the CPU caches, causing lots of reads from memory, while the interpretter did not. It is often the case that interpretting is fast enough and that there is no need for compiling (to machine code or virtual machine).

Comment Re:wireless sensor network (Score 1) 67

The LoRa network has some measurements against these kind of attacks. I built a LoRa node myself (to connect to the free network owned by with only limited coverage, see and had to generate two private/public keys, one for the wireless connection and one for the application, meaning that the transmitted information is encrypted. There is also frame counting implemented. The maximum rate on this free network is limited to about 80 bytes per hour. Maybe the commercial network has a slightly higher rate and is bi-directional. The railway station of Utrecht has connections in five directions and is know to cause massive delays in the very tightly scedule rail network in the Nethelands due to (for example) frozen rail switches. So, I guess they are only using it to signal these kind of things. Not something as vital as the position of the switch.

Comment Self taught (Score 1) 515

I learned Algol 60, FORTRAN, and Lisp while still in high school. Writing programs out on paper before traveling to a near by city by train to make punch cards and run the programs, often going home with s stack of listings to study the results. Only in second year of university did I learn something truely new: currying and lazy evaluation. More details.

Comment Re:It time, this will be good for Lee Sedol (Score 1) 111

I felt that both the commentaries on the official stream and the one of AYA with Kim Myungwan were mostly focusing on analysing alternatives to moves that were already played, instead of focusing on possible moves to be played. At one point Haijin Lee, also known as Haylee, the current secretary of the International Go Federation, took a seat behind the computer. While Lee Sedol was taking a long time to think about the 78 move, she suggested the "wedge" move to Kim Myungwan. He first asked with some surpise: "This one?", and after she confirmed he exclaimed: "O, that is very creative". They analyzed the various possibilities to take benefit of the move, but did not see how it could work. Haijin at one time remarked, "It has to work", indeed because otherwise the game would be a loss. Then with still 6:16 on the clock, Lee Sedol played the proposed "wedge" move at L11. Then Haylee has to go. Then AlphaGo plays the move that Kim Myungwan just played as a possible continuation. Soon it is acknowledged that it is a mistake and that the chances for Lee Sedol have turned. The "wedge" move is later recognized as the genius move with which Lee Sedol defeats AlphaGo. Demis Hassabis tweeted Mistake was on move 79, but #AlphaGo only came to that realisation on around move 87 and When I say 'thought' and 'realisation' I just mean the output of #AlphaGo value net. It was around 70% at move 79 and then dived on move 87. The question remains if there is another move that AlphaGo could have played to prevent Lee Sedol from winning. If this is not the case, then move 78 is simply an over play that tricked AlphaGo.

It seems that AlphaGo suffers from the horizon effect, meaning that when it is ahead, it becomes blind for wining sequence that starts with an unusual move. It is great that Lee Sedol has won this game, because it shows that humans still have a better understanding of the game. Relying on a mental vocabular for reasoning about the game, has some weaknesses, it might still prove superior when reasoning about very complex situations like the one encountered in this game. It seems that Lee Sedol took most time to think about this move. Later on in the game, AlphaGo, played some bad moves, probably because its winning percentage had dropped.

Comment Already on the market: Xsens MTi-G (Score 1) 127

A product with these specifications seems to be already available on the market: MTi-G by Xsens. The technical specifications talk of a resolution of 2.5 cm, which is about an inch. It uses the kind of sensor fusion algorithms described in the article. Xsens is a Fairchild Semiconductor company, an industry icon delivering power solutions for the mobile, industrial, cloud, automotive, lighting, and computing industries. Xsens has offices in Enschede, the Netherlands and Los Angeles, California.

Comment Re:Over use of back-tracking (Score 1) 230

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.

Comment Over use of back-tracking (Score 1) 230

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.

Comment Radars remain essential in Europe (Score 1) 52

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.

Comment Re:Like Coca Cola, git is the real thing (Score 1) 203

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.

Comment Re:Like Coca Cola, git is the real thing (Score 1) 203

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.

Comment I would consider you an expert (Score 1) 220

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.

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