User talk:MatEngel

Fundamental solutions to the eight queens problem

The current article [[1]] shows the 12 "fundamental" solutions of the 8 queens puzzle. It does not tell the user that some of them are "not very different". I did a change to insert this information, with small explanation. Another user ([[2]] reverted my change, with remark "revert good-faith addition; probably OR, nonstandard terminology. Queens do not live on a torus, so these are not true symmetries.)"

My answer to this remark: "Queens do not live on a torus": if queens live on the board, they live also on what he calls torus; it is for me like: an inhabitant of London is also an inhabitant of England. He may be proud to be inhabitant of London and almost forget he is inhabitant of England, but he still is. Coming back the queens: the board can always be viewed periodically, which leads to the torus perspective. The problem is more that symmetries depend depend on the allowed moves. Mathematically speaking they arise from groups acting on a set; here, the set is the board, and you can choose different groups. If you restrict you to the dihedral group (only rotations by 90°, and reflection at middle axis), you get the 12 fundamental solution. This group is perfect, as it carries solutions always to other solutions, and non-solutions to non-solutions. Bigger groups which contain also the shift operations can mix solutions with non-solutions; nevertheless, they are "true symmetries" of the board, and give the insight, that some of the fundamental solutions are close to each other.

I tried to insert this point, without too much mathematical terminology, and still think it is worth to have it in the article.

Comments on my point are welcome!

Welcome!

Hello, MatEngel, and welcome to Wikipedia! Thank you for your contributions. I hope you like the place and decide to stay. Unfortunately, one or more of your edits to the page Waterfall model have not conformed to Wikipedia's verifiability policy, and may be removed if they have not yet been. Wikipedia articles should refer only to facts and interpretations that have been stated in print or on reputable websites or other forms of media. Always remember to provide a reliable source for quotations and for any material that is likely to be challenged, or it may be removed. Wikipedia also has a related policy against including original research in articles. Additionally, all new biographies of living people must contain at least one reliable source.

If you are stuck and looking for help, please see the guide for citing sources or come to the new contributors' help page, where experienced Wikipedians can answer any queries you have! Here are a few other good links for newcomers:

I hope you enjoy editing here and being a Wikipedian! Please sign your name on talk pages using four tildes (~~~~); this will automatically produce your name and the date. If you need help, check out Wikipedia:Questions, ask me on my talk page, or ask your question on this page and then place {{help me}} before the question. Again, welcome! Walter Görlitz (talk) 14:01, 23 September 2014 (UTC)[reply]