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Atractor is a Portuguese non-profit association, based in Porto, devoted to maths popularization. Their main activities are listed below:

The DVD "Symmetry, the dynamical way"

(Simetria, apresentaçao interactiva. Launched in Summer 2009, 6 languages). This DVD was created by Atractor and it aims to give a presentation (as elementary as possible) of orbifold ideas applied to the classification of planar symmetry. The DVD is not a film; it contains a lot of interactive applications about the symmetry in the plane. There, you can see "stamps" (orbifolds) stamping the 17 different patterns of plane tilings (wallpaper groups) and the 7 different patterns of strip tilings (frieze groups). You can get an idea about why there is only a limited number (17+7) of tilings/friezes, by playing a "game" and trying to combine different symmetries so that you get all possible combinations with (fractionary) Euler number 0.


GeCla stands for Generation and Classification, and it is a program to explore plane symmetries. The program contains 4 different modes:

  • Find Symmetries. With this tool you can try to find the symmetries of an image.
  • Generation of rosettes, friezes and patterns. You can use this tool to generate your own symmetric images. The file images which are generated are not "ordinary images" in the sense that, included in the jpeg file, the program also saves information about its symmetry group. So if, afterwards, you open these images in GeCla, GeCla will know which are the symmetries of these images and it can help you with the classification.
  • Classification. This is similar to "Find Symmetries", but it is a bit more sophisticated. You can use the program to classify the image according to its symmetry and you can decide whether you need or not help from the program. In the end, the program provides a report of the errors committed.
  • Competition. This allows organizing competitions between students in which they generate images and then classify the ones made by their opponents. These competitions can be done online.

GeCla already has versions in five languages: EN, IT, GE, PT and SP.

The exhibition "Symmetry, playing with mirrors"

(Simetria, jogos de espelhos). The original exhibition comes from the University of Milan (Italy) -(Simmetria, giochi di specchi)-, Atractor adapted and enlarged this exhibition, which is hosted in the Rectory of the University of Porto (Porto, Portugal). A travelling copy has gone to more than 50 places in Portugal and abroad.

The exhibition "Mathematics Alive"

(Matemática Viva). Matemática Viva (Maths Alive) was a math exhibition, created in 2000, to celebrate the International Year of Mathematics. It contains more than 60 exhibits and was on display in Pavilhão do Conhecimento (Lisbon, Portugal) for 10 years.


AtrMini AtrMini is a set of virtual games aimed at younger users, and which can be downloaded for free from Atractor's site. There are versions available for PC (Windows and Mac) and also for tablet and smartphone, for Android and IOS system.

Atractor's site

Atractor's site contains more than 2000 webpages devoted to Mathematics Promotion, most of them illustrated by images and interactive applications, such as applets, CDFs and flash applications.