#s of Combinations and Permutations of lines?

In summary, there are formulas that exist for calculating the total number of combinations and showing the breakdown of combinations for any starting configuration of lines. However, there is no known formula to calculate the total number of permutations for any given starting configuration. It would require a more advanced mathematical approach or a brute force method to find all possible permutations.Thank you for reading and I hope this helps!
  • #1
Laubarr
1
0
Hello All,

See picture below:
1601180253662.png

There exist an infinite plane with infinite number of dots. For sake of argument, let's assume they are 1 inch away from each other.

However, below(on your far left) you can see 3 lines already made. The last line is the yellow one.
What you see on the left, are all combinations of possible moves. Move is defined as structure of lines until you reach an empty dot.
Thus, there are 6 combinations of single line(on top). While on bottom you see 10 combinations. 5 of them moves with 2 lines, and 5 with 3 lines.
Total # of combinations is 16.
1601180359244.png

So far so good?
Well the basic unsolved question are:
* Does formula exist to calculate total number of combinations(16 in this case) just by looking at the initial graph of 3 lines?
** Does formula exist to show the breakdown of all combinations (6 for single line, 5 for 2 lines, 5 for 3 lines?
*** is 16 the biggest number of combinations that you can make from 3 line starting configuration? For instance: Try to calculate # of combinations (1 lines, 2 lines, 3 lines) from this initial variation:
1601180757545.png


To not spoil the fun, i will just say there is more than 16. So is this the best solution? How we can prove that this is the best we can do? Obviously we can prove that just by doing all 3 line configurations by hand, but what if we take it to next level? What's the best 4 line configuration and how many combinations it has? How about 5,6.7...(n) ? The tree expands quite rapidly, and also few things need to be explained:

Combinations vs Permutations:

1601181037227.png


Above, there are 4 lines as starting configuration. In this case, there are 36 combinations OR 41 permutations. The reason is because you can go from A > B > C > D or C > B > A > D. Once again, is the a formula to calculate combinations (36) and Permutation(41) from any starting configuration?

1601181237398.png


Notation + Final info to consider:

1601181970060.png


Using above notation, you can notice that each configuration is unique and might have different #s of combinations and or permutations. For example:

1601182436602.png


Anyone with any input, either mechanical or potentially writing a code to get the answers How many combinations/Permutations for each variation with up to 10 lines as a starting configuation, would be greatly appreciated. If your program can handle bigger starting configurations, that's even better!

Thank You and enjoy! :)
 
Mathematics news on Phys.org
  • #2


Hello there,

I can definitely provide some insights and potential solutions to the questions posed in the forum post.

Firstly, to answer the question about the formula for calculating the total number of combinations, it is possible to do so using a mathematical concept known as combinations with repetition. In this case, the number of combinations can be calculated using the formula n^r, where n represents the total number of distinct elements (in this case, lines) and r represents the number of elements in each combination. So for the example given, where there are 3 lines and each combination consists of 2 lines, the formula would be 3^2 = 9 combinations. This can be extended to any number of lines and combination sizes.

To show the breakdown of all combinations, we can use another mathematical concept called binomial coefficients. This allows us to calculate the number of ways to choose r elements from a set of n elements. In the example given, where there are 3 lines and each combination consists of 2 lines, the formula would be (3 choose 2) = 3 combinations. This can also be extended to any number of lines and combination sizes.

Moving on to the question about whether 16 is the biggest number of combinations for a starting configuration of 3 lines, the answer is no. As mentioned in the post, there are more than 16 combinations for this starting configuration. To prove this, we can use the formula mentioned earlier (n^r). For 3 lines and combinations of 2 lines, the maximum number of combinations would be 3^2 = 9. So there are definitely more than 9 combinations in this case.

As for the question about the best 4 line configuration and the number of combinations it has, the same concepts can be applied. Using the formula n^r, we can calculate that there are 4^2 = 16 combinations for a starting configuration of 4 lines with combinations of 2 lines. This can also be extended to any number of lines and combination sizes.

To answer the question about combinations vs permutations, it is important to understand the difference between the two. Combinations refer to the number of ways to choose a subset of elements from a larger set, while permutations refer to the number of ways to arrange a set of elements in a specific order. In the example given, there are 36 combinations but 41 permutations because some combinations can be arranged in different orders to
 

FAQ: #s of Combinations and Permutations of lines?

What is the difference between combinations and permutations?

Combinations and permutations both involve selecting items from a set, but the key difference is that in permutations, the order of the selected items matters, while in combinations, it does not. For example, choosing three out of four colors in a specific order would be a permutation, while choosing three colors without regard to order would be a combination.

How do I calculate the number of combinations or permutations?

The formula for calculating combinations is nCr = n! / (r! * (n-r)!), where n is the total number of items and r is the number of items being chosen. For permutations, the formula is nPr = n! / (n-r)!, where n and r have the same meaning. Alternatively, you can use a combination or permutation calculator to save time and avoid errors.

Can I use combinations or permutations in real-life situations?

Yes, combinations and permutations are used in many real-life situations, such as in probability and statistics, in determining the number of possible outcomes in games and puzzles, and in creating unique passwords or codes.

Are there any limitations to using combinations and permutations?

One limitation is that they can only be used for selecting items from a set, so they may not be applicable in all situations. Additionally, as the number of items or the number of items being chosen increases, the number of combinations or permutations can become very large and difficult to calculate.

Can combinations and permutations be used in combination with other mathematical concepts?

Yes, combinations and permutations can be used in combination with other mathematical concepts, such as probability, factorials, and binomial coefficients. They are also closely related to the concepts of combinations with repetition and permutations with repetition.

Similar threads

Back
Top