Calculating Number of Distinct x Tuples from a Set A

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Discussion Overview

The discussion revolves around calculating the number of distinct x-tuples that can be formed from a set A, specifically focusing on combinations of ordered pairs and the implications of order and distinctness within those pairs. The scope includes combinatorial reasoning and mathematical formulations.

Discussion Character

  • Exploratory
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • Some participants seek to clarify whether the term "tuple" refers to ordered pairs or sets, indicating a potential misunderstanding of notation.
  • One participant suggests that the goal is to find combinations of 14 numbers from a set of 20, treating them as ordered pairs, while emphasizing that the order of the pairs does not matter.
  • Another participant explains that an n-tuple is a sequence where order matters, and proposes a definition for n-combinations involving disjoint sets.
  • Several participants discuss the need to account for the order of elements within ordered pairs and how to adjust calculations accordingly.
  • One participant proposes a method involving combinations and permutations to calculate the number of distinct tuples, while another challenges the correctness of this approach.
  • Another participant introduces a method of counting distinct pairs by considering the total number of pairs and subtracting those with non-distinct terms.
  • One participant suggests a combinatorial approach using combinations of elements from the set, while noting the need to divide by the factorial of the number of pairs to account for the order of tuples.
  • There is a suggestion to explore patterns through examples to better understand the problem, indicating a preference for empirical reasoning.

Areas of Agreement / Disagreement

Participants express differing views on the definitions and implications of tuples versus sets, as well as the correct approach to calculating the number of distinct tuples. No consensus is reached on a definitive method or solution.

Contextual Notes

Participants highlight the importance of distinguishing between ordered and unordered combinations, as well as the necessity of ensuring that elements are not reused across pairs. There are unresolved questions regarding the assumptions made in the calculations and the definitions used.

  • #31
BicycleTree, you are not allowed to swap a key that has already been swapped.

This is what is meant when he said:

Think of it as a physical system containing 10 physical elements, if 1 is used in one pair, it can't be reused in another pair or again in the same pair.
so, (2, 2) can't be used and (2, 3), (2, 4) can't be used.
 
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  • #32
Yeah, but that doesn't strictly apply to the keyboard example. It's not really important.
 

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