Today I want to share with you a purchase that was made furrowing the expanses of aliexpress.
The review will be devoted to an excellent puzzle toy - the Rubik's Cube or as it is popularly called the Rubik's Cube. In the review, in addition to the review of the cube itself, assembly options will be considered.
All interested are invited to read.
Some facts about the Rubik's Cube
The Rubik’s Cube is a mechanical puzzle invented in 1974 (and patented in 1975) by the Hungarian sculptor and architecture teacher Ernö Rubik.
The puzzle is a plastic cube.(form factor in the original version 3? 3? 3). Its visible elements on the outside look like 54 faces of small cubes that make up one large cube, and are able to rotate around the 3 internal axes of the cube. Each face consists of nine squares and is painted in one of six colors, in one of the most common color options arranged in pairs opposite each other: red - orange, white - yellow, blue - green; but in different versions of the Rubik's cube, the faces are painted in different colors in a completely different way. Rotating faces allows you to reorder colored squares in many different ways. The player’s task is to “collect the Rubik's Cube”: turning the faces of the cube, return it to its original state, when each of the faces consists of squares of the same color.
The Rubik's Cube is believed to be a leader among toys.according to the total number of sales: around the world, about 350 million Rubik's cubes were sold, both original and various analogues. An interesting fact: if they are put in a row, they will stretch almost from the pole to the pole of the Earth.
Well, what do we have: The cube came in a well-packed one, wrapped in a “little bubble”, but the corners of the packaging still suffered, apparently it was already packed like that.
In addition to packing, the cube was packed in a plastic bag, the cube came assembled, but I could not resist and twisted it, so there is no beautiful photo of the assembled cube.
What was my surprise when the assembly instructions appeared at the bottom of the box, but unfortunately only in Chinese.
The dimensions of the cube are 5.7cm * 5.7cm * 5.7cm, made of plastic that is pleasant to the touch, color elements are made qualitatively and made of the same plastic from which the cube is made.
All sections are disassembled, apparently this is done for convenient disassembly of the cube and cleaning
Cube Weight 102 grams
Having examined the cube in detail, let's move on to the assembly method.
There are many methods for assembling a rubik's cube, one of the most popular is CFOP method
The most popular speed assembly methodthe cube is the CFOP method, it is also the Jessica Friedrich method, which finalized and popularized it, although other people also contributed. If everything is done correctly, the average die can be collected in 56 moves (alas, not in twenty). There are other methods with which you can get good results: Petrus, ZZ, Roux, etc. They are less popular and for the sake of brevity we will restrict ourselves to the CFOP method.
CFOP is the name of the four stages of assembly: Cross, F2L, OLL, PLL:
Cross - Cross
The purpose of the stage is to correctly place fouredge cubes on one of the faces. Anyone who knows how to collect the cube at least somehow will cope with this, but collecting the cross in a few seconds is not so trivial. According to the rules of the competition, before assembly you are given 15 seconds to learn the combination (inspecting), for which at least you need to find these four edge cubes, and it would be nice to draw up a complete sequence of moves in your head. It has been proved that no more than eight turns are always required to assemble a cross on a preselected face (a 180 ° turn is considered to be one), and eight are extremely rare, and seven are infrequent (the average is slightly less than six). In practice, to quickly learn how to find the optimal sequence, it takes a lot of training.
You can choose a face for the assembly of the cross in different ways. The most popular way is to always collect it on the same face (often on white). Then you at all stages of assembly know exactly the relative arrangement of colors, which facilitates the process. Some people are the first to collect the facet that is easiest to collect. On average, this saves one turn, but you constantly have to readjust to a different arrangement of colors. A compromise option is also used - to collect one of two opposite faces (say, either white or yellow), then the set of colors of the side faces does not change.
The main trick of assembling the cross is that itneed to collect relatively. For example, if you are collecting a cross on a white face and a white-blue edge cube is already standing on it in white towards the white center, then it is not so important for you whether the blue side of this cube is aligned with the blue face. It is enough to put a white-green cube on the opposite side, and white-red and white-orange on the left and right. During the assembly process, you can twist the white face as you like, and in the end, with one movement, immediately combine all the side centers with the cubes of the cross. It is only important to remember the exact order of the colors on the cube: if you look at the white side, then blue, red, green, orange (yellow is behind).
Professionals collect a cross on the bottom. It seems difficult for beginners, since it’s almost not visible what you are collecting, but this gives a great advantage when moving on to the next stage: you don’t have to spend time on turning the cube, and during the process of building the cross you can notice the arrangement of the cubes needed to build F2L and outline a plan for further assembly.
F2L - the first two layers; Perhaps the longeststage, the purpose of which is to collect completely two layers: a layer with a cross and an intermediate layer. Essentially, you need to put eight cubes in place: four corner lower layers and four side edges in the middle layer. Unlike assembly methods for beginners, a pair (column) from an angular and an edge cube is assembled immediately (that is, four such pairs must be assembled). Depending on the initial arrangement of the cubes of the pair, you need to apply one or another algorithm (sequence of turns). There are more than 40 such algorithms; you can just memorizeHowever, almost all of them are displayed intuitively. There are two simple cases when a couple is going in three movements: first case and second case
The main difficulty of the stage is to quicklyFind paired cubes. They can be in 16 different places: 8 places in the last layer and 8 in the columns. The columns are more difficult to view, and the less columns you have collected, the more chances are that the cubes you need are in the unassembled ones. If you did not pay attention to the cubes for F2L when assembling the cross, when you go to this stage, you can lose a lot of time just looking. It is also not always wise to start with the first pair found: it is possible that it is going to be a long algorithm, and if you start with another, then in the process the first one will be rebuilt into a more successful combination.
OLL - orientation of the last layer
At this point, the cubes of the last layerThey are oriented so that the last (in our case, yellow) face is collected. At the same time, it does not matter that the cubes, in fact, do not stand in their places: we will do this at the last stage.
There are 57 different initial situations foreach of which has its own build algorithm, from 6 and somewhere up to 14 moves. It is necessary not only to learn all these algorithms, but also to quickly identify which one is necessary to apply at the moment. Here is an example of one of OLL:
The above picture shows the initial situation withaccuracy to the turn (it is assumed that we are collecting the yellow face). To apply this OLL, the yellow squares must coincide not only on the upper side, but also on the side (we ignore the squares of the other colors). It is not always necessary to compare the cube with the circuit completely, you just need to compare enough squares to distinguish it from other combinations. On the right are two algorithms (it’s more convenient for someone to do one, for someone else) in standard notation, below is the OLL number and the probability of its occurrence. Almost all fall out with a probability of 1/54, some with 1/108 and two with a probability of 1/216 (including the lucky combination when OLL got together).
Beginners memorize 57 combinations canseem like torture, so a simplified, but slower version is invented - 2-look OLL. In this case, OLL is divided into two stages, first the cross is assembled, and then the corners. Here you need to memorize only 10 algorithms (3 for the cross, 7 for the corners). Having gained experience in 2-look OLL, you can slowly take up the study of the complete set. In this case, 2-look in any case come in handy: firstly, they are all in a complete set (say, if the cross is assembled itself, then the full OLLs coincide with the 2-look OLL for corners), and secondly, if you come across unfamiliar OLL, you can return to 2-look.
PLL - permutation of the last layer
The final stage of assembly is toplace the cubes of the last layer in the right places. The approach is approximately similar to the previous stage, but there are fewer combinations and algorithms, only 21 (13, if we consider mirror and inverse for one). On the other hand, they are somewhat more difficult to identify, since here you need to take into account different colors, and the colors in the diagram may not coincide with your colors (accurate to the cyclic permutation):
The arrows indicate the cubes that this PLL permutes. The probabilities of most combinations are 1/18, occasionally 1/36 and 1/72 (including the lucky chance when you do not need to do anything).
Again, a simplified version is proposed - 2-look PLL, when first the angles (two combinations) are placed, and then the centers (four combinations), they are quite easy to learn.