Puzzles are not only entertainment, but also a good exercise for the mind. The classic Rubik's Cube appeared in 1974. However, it is still enjoyed by adults and children. But few people know that there is one more similar puzzle - a triangular Rubik's cube, it is Meffert’s pyramid, “Moldavian pyramid” or “Japanese tetrahedron”. After numerous independent attempts to paint the sides of the pyramid in plain colors, the mystery of how to assemble a triangular Rubik's cube haunts many. It is time to solve this puzzle.
A bit of history
Those who first see Meffert’s pyramid mistakenly assume that it was invented based on the Rubik’s cube diagram. But this is not so. Meffert's pyramid appeared 3 years earlier than the usual cubic puzzle. It was invented by a German entrepreneurial young man, Uwe Meffert.
Initially, he made this toy for his own entertainment, using several pieces of wood, an elastic band and a central ball. It didn’t even occur to him that this puzzle could be interesting to anyone else. But that all changed when, in 1975, Erne Rubik patented the Rubik's Cube and began to promote it to the masses. Then Meffert remembered his pyramid and made the whole world think about how to assemble a triangular Rubik's cube.
Design
The design of the puzzle plays a key role in its solution. Therefore, before you learn how to assemble a triangular Rubik's cube, you need to understand what it is.
Meffert's pyramid consists of:
- 4 axial elements;
- 6 rib elements;
- 4 trivial angular.
Each axial element, in turn, has triangles facing three adjacent faces. Meffert’s pyramid is designed in such a way that each of its fragments during rotation can easily move and not fall out of it.
If we talk about how to collect a triangular Rubik's cube, it should be noted that with this puzzle design, 75,582,720 configurations are possible. This figure is not so scary, considering that the design of the classic Rubik's Cube implies 43,252,003,489,956,000 possible states.
Modifications
In addition to the Meffert pyramid and the Rubik's Cube, there is another similar puzzle - tetraminx. With the shape of a truncated tetrahedron, it visually resembles the “Moldavian Pyramid”. But, despite the similarity, it has a completely different mechanism.
People who understand how to assemble a Rubik's 3x3 cube, the assembly scheme of which is available to everyone today, can easily deal with tetraminx. Because, unlike the Meffert pyramid, in the tetraminx you need not only to arrange the colors on its sides, but also to restore the tetrahedron itself.
God Algorithm
God's Algorithm is a well-thought-out puzzle solving algorithm in which you need to perform a minimum number of actions. This applies to all puzzles that have a finite number of configurations and moves. These include: the Meffert Pyramid, the Tower of Hanoi, Taken.
How to collect a Rubik's Cube? Schemes for beginners are based on the algorithm of God, which implies finding the optimal solution to the puzzle to return the initial configuration of the pyramid to the final one.
God number
From the definition of the algorithm of God follows another concept - "the number of God." This is the maximum number of moves for which you can solve the puzzle with the most difficult initial configuration. That is, this is such a number for which the Meffert pyramid and other similar puzzles can always be solved. If the number of moves exceeded this number, then the solution was broken by the algorithm of God.
If we talk about how to assemble a 3x3 Rubik's cube, then the assembly diagram, made mathematically correct, cannot exceed 20 actions. For Meffert's pyramid, the maximum number of moves for which it can be solved is 11.
How to collect a triangular Rubik's cube? Method 1
Having understood the structure and basic terms used in the assembly of the “Mongolian pyramid”, you can proceed directly to the process itself. It is much easier to assemble a tetrahedron than a cube. Therefore, it is better to start getting acquainted with such puzzles from him.
Step-by-step guide:
- Carefully consider all the faces of the pyramid and expand its vertices so that they coincide with the color of the middle element.
- On one side, expand the middle tetrahedra so that the three vertices with the triangles in contact with their sides are the same color. To understand which side to start folding the pyramid, you should look at the top of the opposite side. The side of the final configuration of the pyramid will be the color that is not on it.
- Build the base of the pyramid. To do this, select the lower central triangle, which has the same color with the face under construction. Then turn the axis on which it is located to the right. The horizontal row below the top of the pyramid is to the left. Return the working axis to its original position. The horizontal row must be turned to the right.
- To build the bottom row, you need to look at the result. If the triangle of the desired color is on the face under construction, turn the three diagonal elements on the lower left vertex to the left. The horizontal row under the central apex is to the left. Repeat the first step in the opposite direction. If the desired color is not on the face under construction, then the central part of the pyramid is rotated counterclockwise. The horizontal row under the central apex is to the right. And again, the first action is repeated, only clockwise.
- Rotate the vertex until the faces are fully assembled and turn the pyramid down.
All other sides of the tetrahedron are assembled in the same way. This is the simplest and most common scheme, how to assemble a triangular Rubik's cube. If, with the correct sequence of actions, the puzzle remains unsolved, you need to check the design of the pyramid. Perhaps it was violated during production.
Method 2
The second method is designed for high-speed assembly of the Meffert pyramid. Layering allows you to cope with the task in just 30 seconds. But the base is built in the same way as in the first method. Further, the process depends on the resulting configuration.
If 2 rib elements are located in their places in the expanded position, then:
- Turn the three diagonal elements on the lower right vertex down.
- Three diagonal elements on the bottom left vertex - down.
- In the same sequence, perform these actions in the opposite direction.
If 3 triangles at the vertex are not located in their places, but when they are rotated 120 degrees, they become correct, violating the position of the vertex and the central element:
- When the desired triangles are on the right side of the source, the three diagonal elements on the lower right vertex need to be turned down.
- The horizontal row under the central apex is to the right.
- Repeat the first step in the opposite direction.
- Turn the horizontal row under the central peak to the right again.
- Three diagonal elements on the lower right vertex - down.
- The horizontal row under the central apex is to the right.
- Three diagonal elements on the lower right vertex - up.
When the necessary elements are on the left side, the actions are similar, only they need to be done in the opposite direction.
How easy is it to assemble a 3x3 Rubik's Cube? Schemes for children allow you to quickly get the hang of such an exciting process, but you should start training with the pyramid. Thanks to the design, it can be assembled in just 11 moves with all possible configurations. Therefore, the desired result can be achieved much faster, which will inspire the solution of more complex puzzles.