Consider a 4 colored cube of 343 small cubes each of dimension 1x1x1 having one particular color. No two consective cubes on the other sides can be of same color.

(a) How many at most smaller cubes of each color are possible.

(b) At most how many cubes of different colors would be visible from a single point in space

(c) At most how many cubes of each color in diagonal would be visible from the same point.

Saroosh Sep 12, 2024

#3**0 **

Analyzing the Cube

Understanding the Constraints:

The cube is composed of 343 small cubes (7x7x7).

Each small cube has one of four colors.

No two consecutive cubes on any side can have the same color.

Visualizing the Cube: Imagine the cube as a stack of 7 layers, each layer being a 7x7 square.

Determining the Maximum Number of Cubes per Color

Strategy: We'll start by considering one face of the cube and then extend the logic to the entire cube.

Considering One Face:

On a single face (a 7x7 square), the maximum number of cubes of a single color would be achieved by alternating colors in a checkerboard pattern.

In this pattern, there would be 25 cubes of one color and 24 cubes of another.

Extending to the Entire Cube:

To ensure no consecutive cubes on any side have the same color, we can alternate colors between layers.

This means that half the layers would have one color pattern, and the other half would have the opposite color pattern.

Calculation:

Total cubes = 343

Half of the cubes = 343/2 = 171.5

Since we can't have half a cube, we'll round down to 171.

Therefore, the maximum number of smaller cubes of each color possible is 171.

bader Sep 12, 2024

#5**0 **

Part (b):

To determine how many different cubes of various colors could be visible from a single point in space on a colored cube made up of 343 small 1x1x1 cubes, let's first analyze the structure of the overall cube.

The cube consists of \( 343 = 7 \times 7 \times 7 \) small cubes. The entire cube itself is 7 cubes along each edge.

When viewed from a vantage point, we can typically see three faces of the cube (the top face and two adjacent side faces). We need to ensure that no two adjacent small cubes on these visible faces have the same color.

Given that there are 4 different colors available, we can assign colors to the small cubes while adhering to the restriction of not having adjacent cubes of the same color.

Let's set up a coloring scheme based on the structure:

1. Each face of the cube is made up of \( 7 \times 7 = 49 \) small cubes.

2. Only the outer layer of cubes is visible on these three faces. The three visible faces share some edges and corners at their intersections.

### Counting visible cubes

Since we are looking at three faces:

- The top face has 49 cubes.

- The two side faces also have 49 cubes each, but they share 7 cubes along the edge with the top face and share 7 cubes on the vertical edge between them.

From the above:

- Total cubes from three faces without accounting for overlaps: \( 49 + 49 + 49 = 147 \)

- Overlap from the shared edge between the top and each side face (7 cubes each): \( -7 - 7 \)

- Overlap from the corner cube (counted in both side faces and on top): \( +1 \)

So, the total unique visible small cubes:

\[

147 - 14 + 1 = 134 \text{ cubes}

\]

### Conclusion on the maximum number of visible colors

To maximize the number of visible colors while respecting the adjacent color restriction, we can use a checkerboard-like pattern on the faces.

Given that there are 4 colors and color assignments can be chosen judiciously, you can easily keep up with the requirement of different colors on adjacent cubes.

Based on the checkerboard coloring on such patterns, essentially you can effectively show all 4 colors visible from a single viewing point while adhering to the adjacent color restriction, especially since you're viewing three faces.

### Answer

Thus, at most **4 cubes of different colors** can be visible from a single point in space while satisfying the color adjacency condition.

bader Sep 12, 2024

#6**0 **

Here is part (c).

Analyzing the Cube and the Viewing Point

Understanding the Problem:

We have a 7x7x7 cube with alternating colors on adjacent faces.

We want to maximize the number of cubes of a single color visible in a diagonal.

Key Points:

The maximum number of cubes visible in a diagonal depends on the orientation of the viewing point.

We need to find the optimal viewing point to maximize the number of visible cubes of a single color.

Determining the Maximum Visible Cubes

Optimal Viewing Point:

To see the maximum number of cubes of a single color in a diagonal, we need to position the viewing point directly in front of a corner of the cube. This will ensure that we can see the longest diagonal.

Visualizing: Imagine the cube with a corner facing you. You'll see a diagonal going from the top corner to the bottom corner of the opposite face

.

Counting the Cubes:

In a 7x7x7 cube, the longest diagonal consists of 7 cubes.

Since the colors alternate on adjacent faces, every other cube in this diagonal will be the same color.

Calculation:

Number of cubes in the diagonal = 7

Half of the cubes = 7/2 = 3.5

Rounding down, we get 3.

Therefore, the maximum number of cubes of each color visible in a diagonal from a single point is 3.

AnswerscorrectIy Sep 13, 2024