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Víktor Bautista i Roca
Lives in Santa Coloma de Gramenet
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Víktor Bautista i Roca

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Science GIF Hall of Fame inductee #001: Striking a flint is like sparking a tiny galaxy or two
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Víktor Bautista i Roca

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Tot en u: feixistes, homòfobs, idiotes i analfabets
All in one: Fascists, homophobes, idiots and analphabets
Un fatxa homòfob porta una bandera que  barreja l'arc de sant Martí amb una estelada, on hi ha escit: «Queréis independencia... pues que os den por culo». I un altre fatxa homòfob que possiblement no sap llegir es pensa que és un gai independentista i l'agredeix. Impagable.
A homophobic fascist carries a flag that mixes the rainbow flag with the pro independence Catalan flag, where you can read, literally, «You want independence... so get fucked in the ass». And another homopnobic fascist, who probably cannot read, thinks the first one is a pro-independence gay, and physically assaults him. No words.
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Perfect Squared Squares

It is easy to tile a square area using smaller square tiles that are all the same size as each other, but tiling a square area using smaller square tiles that are all of different sizes is much harder. 

This picture shows one possible way to tile a 1376 by 1376 square using smaller square tiles that are all of different sizes. The numbers in each smaller square denote the length of each of its sides, as opposed to its area. The solution in the picture has another remarkable property: it is not possible to form a rectangle from the union of a subset of the tiles, except in trivial ways. 

A rectangle that is partitioned into smaller squares is known as a squared rectangle. If the rectangle happens to be square, then it is known as a squared square. If all of the smaller squares have different sizes, the squared square is called perfect, and if no proper nontrivial union of the smaller squares forms a rectangle, the squared square is called simple. The configuration in the picture is therefore an example of a simple perfect squared square, or SPSS for short.

The history of perfect squared squares is surprisingly long. It starts in 1902 when H.E. Dudeney published a puzzle called Lady Isabel's Casket. The puzzle involves partitioning a square into different sized smaller squares together with a rectangle. In 1903, Max Dehn proved the key result that a rectangle can be tiled by squares if and only if its length is a rational multiple of its width. This result can be used to show that if a tiling by squares is possible, then the rectangle can be scaled in such a way that all of its side lengths, as well as all the side lengths of its constituent squares, are integers. Since 1903, a large number of examples of squared rectangles have been produced by many mathematicians. The history of the subject is surprisingly rich, and is recounted in detail in the paper http://arxiv.org/abs/1303.0599 by Stuart E. Anderson.

The simple perfect squared square in the picture was discovered in 2013 by James B. Williams using a computer search. It has the distinctive feature that none of the seven largest constituent squares (shaded in purple) appears as a corner piece (shaded in green).

Now I know what you're thinking. What happens if you try to construct a similar type of square tiling on a cylinder? Or a Möbius strip? Or a Klein bottle? Or a projective plane? And what happens if we use triangles instead of squares? Well, you'll be pleased to know that the site http://www.squaring.net treats all these cases in detail. (You should have a look at the site, because it probably contains more detail than you are expecting.) The illustration here comes from that website, which is maintained by Stuart E. Anderson.

On the other hand, if you're wondering why people would want to study this, I don't have a good answer, except that it is challenging and aesthetically appealing.

#mathematics #sciencesunday #spnetwork arXiv:1303.0599
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Jugant a Ingress al capvespre
Playing Ingress at dusk
15 persones d'edats variades, tots mirant al mòbil i amb la cara reflectint el verd de les pantalles. Un gran dia. De fet, entre ahir i avui, he caminat 20 km tot jugant.
15 people of different ages, all looking at ther mobile phones, and with their faces reflecting the green of the screens. A great day. In fact, between yesterday and today, I've walked 20 km on the game.
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+maqui nueno ei, que n'hi havia dos que abans eren blaus i s'han canviat. Bàsicament, diuen, pel bon rotllo en el nostre bàndol.
A veure quan t'animes. 
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πR²·2R = 4/3πR³ + 1/3·πR² ·2R
El volum d'una esfera, més el d'un con de la mateixa alçada i radi, és igual al volum del cilindre que la circumscriu.
The volume of a sphere plus a that of a cone of the same height and radius is equal to the volume of the cylinder that circumscribes the sphere.
(c) Rod Bogart
https://twitter.com/RodBogart/status/455123609195802624
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Venda no sedentària?  
Pel que sembla, a nivell legal, de la venda ambulant se'n diu "no sedentària". Suposo que ambulant era massa clar.
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In his circles
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Campanes repicant a l'església major de Santa Coloma
Bells ringing out in my town's main church
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Pluja a mitjanit
Rain at midnight
Pluja just davant de la casa Milà (la Pedrera). Curiós com cada gota porta una direcció diferent.
Rain from just in front of Casa Milà (la Pedrera) , Barcelona. Curious how each drop has a different direction.
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+maqui nueno a la Pedrera ara hi ha una lona que la cobreix i una bastida. Estàvem hackejant els portals quan em vaig adonar que si miraves la pluja de manera que l'estructura de la bastida tapava els focus, les gotes de pluja es veien, mentre que els focus no emprenyaven. 
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Here's a little girl I met on the streets in a little town in Morocco. They all speak French there, and I know a few French children's poems, so I was able to tell her one of them! When I started telling her, she started singing it back to me... and I learned that the poem also has a song-form — she was cool.
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Art By Edgar Zuniga Jimenez
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Very nice :)
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People
In his circles
410 people
Have him in circles
5,079 people
Micaël Reynaud's profile photo
Work
Occupation
Sóc informàtic, però ara em dedico al món dels jocs.
Basic Information
Gender
Male
Birthday
April 22
Story
Introduction
Informàtic de formació, m'hi vaig dedicar durant gairebé 10 anys. Ara estic en una etapa més centrat en el món dels jocs. Per exemple:
  • He creat jocs (alguns han guanyat premis, un ha estat publicat)
  • He fet conferències, xerrades, exposicions... sobre jocs
  • Faig tallers de jocs variats (aualé, toghızqumalaq, jocs de cordills, jocs tradicionals...)
  • He estat voltant per pobles ensenyant jocs motors tradicionals d'arreu del món
  • Participo en campionats, bàsicament d'aualé i toghızqumalaq (vaig ser al primer campionat del món, al Qazaqstan)
I bé, un altre dia explicaré més coses.
Bragging rights
He aparegut a diaris d'Antigua & Barbuda, Suïssa i el Qazaqstan :-)
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Map of the places this user has livedMap of the places this user has livedMap of the places this user has lived
Currently
Santa Coloma de Gramenet
Dilluns 3 hi vaig. Em diuen que sí, que per web hi ha ofertes especials, però que amb ells no es depèn de quan vingui el missatger a portar-te el mòbil i tal. Demano un Xperia SP i la portabilitat. Em diuen que aquest model ara no el tenen a la botiga però que en dos dies el tenen i que a partir d'aleshores, en dos dies més la portabilitat està feta. Dimecres 5 hi torno, que no m'han dit res. Em diuen que avui els ha arribat el mòbil, i que ara iniciaran la portabilitat. Dissabte 8 em diuen que la portabilitat en realitat són entre 24 i 72h, i que els caps de setmana no compten. Dimarts 11 hi torno. Resulta que el mòbil encara no el tenen. Que el de dimecres 5 no era el meu sinó el d'uns altres clients que portaven des de feia un mes esperant-lo. Que potser arriba demà. En resum, que dilluns 1 em van mentir dient-me que era més ràpid i que en dos dies tindria el mòbil, si sabien que hi havia gent esperant-ne de feia un mes. Que dimecres em van mentir dient-me que els havia arribat. I que dissabte van continuar amb la mentida. Un comportament penós.
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Public - 2 months ago
reviewed 2 months ago
Primera impressió correcta. Venen a pes i a part pagues el recipient (pots portar-hi el teu). Encara he de provar el xampú de poma que he comprat. Per cert, ingredients: Aqua, sodium laureth sulfate, magnesium laureth sulfate, cocamidopropyl betaine, aloe barbadensis, polyquaternium-7, hydrolyzed wheat protein, sodium hydroxymethylglycinate, parfum. Afegit: Ja fa uns dies que faig servir el xampú, i bé. Suposo que un dia d'aquests passaré a comprar-hi gel de bany.
Public - 2 months ago
reviewed 2 months ago
Un bon menú del dia, però amb poca varietat vegetariana.
Public - 6 months ago
reviewed 6 months ago
Bona selecció de material. No gaire bona atenció.
Public - 6 months ago
reviewed 6 months ago
13 reviews
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Un lloc històric que cal visitar. Actes culturals interessants. Bon bar restaurant.
Public - 4 months ago
reviewed 4 months ago
Sempre hi he trobat allò que buscava.
Public - 6 months ago
reviewed 6 months ago
Bones pizzes, bones amanides i bon preu. Un únic problema, per a mi. Massa soroll.
Public - 6 months ago
reviewed 6 months ago