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## How Were Rosetta/Philae Operations Scheduled?
Unless you live unplugged you certainly saw the astounding pictures of Comet 67P/Churyumov–Gerasimenko taken by the Philae lander. Besides producing nice images, Philae embarked scientifc instruments , each developed by a European laboratory, to accomplish scientific experiments when approaching, and after landing on the comet. Given that communication takes about 25 minutes between Earth and Philae once landed, it was very important to carefully plan every operations of the mission in advance. Indeed, there... [More]
Tags: constraint_programming analytics |

## Solving the hardest Sudoku - part 1
Do you know the hardest Sudoku problem? Do you know the best way to solve it? Before answering these questions, let me remind you of what the Sudoku puzzle is about in case you haven't read a newspaper in the last decade (adapted from wikipedia ): The objective is to fill a 9×9 grid with digits so that the digits in each column, each row, and each of the nine 3×3 sub-grids that compose the grid (also called ""blocks") are pairwise different. The puzzle setter provides a partially completed grid, which... [More]
Tags: sudoku mathematical_optimization analytics optimization mathematics constraint_programming |

## Tower of Hanoi at Large
Did you know that the Tower of Hanoi puzzle had real world applications? I was lucky enough to be involved with one such application . Before describing the application, let me recap briefly what the puzzle is about. I'll borrow the definition from wikipedia . The Tower of Hanoi (also called the Tower of Brahma or Lucas' Tower , [ 1 ] and sometimes pluralised) is a mathematical game or puzzle . It consists of three rods, and a number of disks of different sizes which can slide onto any rod. The puzzle starts with the disks... [More]
Tags: smarter_city analytics constraint_programming optimization |

## Solving Flexible Job Shop Scheduling Problems
A recent post by Quintq team about solving hard scheduling problems made me wonder how our Constraint Programming Optimizer (CP Optimizer) would perform on the same problems. I therefore contacted Philippe Laborie who is working on CP Optimizer. He worked with another colleague, Petr Vilim, and quickly produced quite interesting results using our forthcoming version 12.6 of CP Optimizer . Here is how Philippe and Petr describe what they did. Jean-François Puget This benchmark is known as Flexible Job Shop... [More]
Tags: constraint_programming benchmark |

## Constraint Programming
Update on september 6 2013. Paul shaw made a great presentation on our Constraint programming Optimizer that complements this post nicely. Slides and replay are available in our developerWorks community. Constraint Programming is one of these key words you may have seen that eludes a precise definition. For some it is a computer programming language paradigm beside imperative programming or functional programming. Such people often speak about Constraint Logic Programming (CLP). For others, including me,... [More]
Tags: artificial_intelligence constraint_programming optimization |