Combinations with Irregular Repetition

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Discussion Overview

The discussion revolves around the combinatorial problem of determining the number of unique decks that can be created in the card game Magic: The Gathering, given specific constraints on card repetitions. Participants explore mathematical approaches to frame an equation that addresses combinations with irregular repetition, particularly focusing on the limitations of card quantities in deck construction.

Discussion Character

  • Exploratory, Mathematical reasoning, Debate/contested

Main Points Raised

  • One participant introduces the problem of calculating the number of unique decks possible given 1729 cards with a limit of 0 to 4 copies for most and unlimited copies for 5 specific cards.
  • Another participant suggests breaking the problem into sub-problems by defining how many of the limited cards are used and proposes summing over different combinations of card usage.
  • A third participant expresses interest in finding existing formulas for combinations with limited repetition and seeks keywords for further research.
  • A later reply proposes using generating functions to find the solution, specifically mentioning the coefficient of x^60 in a particular mathematical expression.

Areas of Agreement / Disagreement

Participants do not reach a consensus on a specific solution or formula, and multiple approaches to the problem are presented without resolution.

Contextual Notes

The discussion highlights the complexity of the problem, including the need for assumptions about card usage and the potential for multiple valid approaches to the combinatorial calculations.

Who May Find This Useful

Individuals interested in combinatorial mathematics, game theory, or card game strategy may find the discussion relevant.

Strymon
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Hey folks, I believe this is the correct thread for this topic. I was debating between general mathematics and statistics. I believe it falls here.

So, I play the card game Magic: The Gathering, and one of the core tenants of the game is building a deck from a large variety of cards. The deck is then randomized (shuffled) and the actual game involves doing your best with the cards you've drawn, as well as knowing what you are likely to draw (reminiscent of poker.) Interestingly, in building a deck, knowledge of statistics is very useful as some cards you may want to see more than others.

One thing I've always been curious of, though, is how many possible decks can be created. It would seem like a simple combination problem, or even Combination with Repetition, except for a problem. Most cards you may have no more than four of in your deck, but there are five cards that you may have any number of in your deck.

=============================

So, here's the question:

A deck consists of 60 cards.
There are 1729 cards of which you may have 0 to 4 copies each in your deck.
There are 5 cards of which you may have any number of copies in your deck.

How many unique decks can be built?

=============================

More than the answer (though I'd be excited to see it,) I'd like to know how to frame an equation that would handle a situation like this. Any thoughts are welcome!

Thanks!
 
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If the problem is too complex to find a direct formula, split it in sub-problems:

Assume N of those 60 cards are used which cannot appear more than 4 times, and M different cards of that type are used (##M\geq \frac{N}{4}##).
This gives well-known problems for the number of combinations for those N cards and the 60-N other cards. I am too lazy to look up the formulas.
Afterwards, you can sum over all N and M.
 
Mfb, thanks for your reply!

I actually was not aware there were formulas for combination with limited repetition like this. I had searched around online briefly but wasn't able to find anything that would quite work, even as a partial solution. Are there some particular keywords I could search under to find them?
 
One way is using generating functions, so the solution is the coefficient of x^60 in (1+x+x^2+x^3+x^4)^1729/(1-x)^5
 

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