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Given a list of (not necessarily distinct) positive integers, $a=(a_1,...,a_n)$, can one reproduce the list (up to reversing the order, i.e. reproduce $(a_1,...,a_n)$ or $(a_n,...,a_1)$) from the underlying multiset, $\{a_1,a_2,...,a_n\}$ and the unordered pairs, $$\left\{\left\{\sum_{i=1}^k a_i,\sum_{i=k+1}^n a_i\right\}\right\}_{k\in [n]}, \quad \left\{\left\{\sum_{i=1}^k (a_i+1),\sum_{i=k+1}^n (a_i+1)\right\}\right\}_{k\in [n]}?$$

If not, how about with the information of any number of `cuts' i.e.

$$\left\{\left\{\sum_{i=1}^{k_1} a_i,\sum_{i=k_1+1}^{k_2} a_i, ..., \sum_{i=k_{l}+1}^n a_i\right\}\right\}_{k\in [n],l\in\mathbb{N}}, \quad \left\{\left\{\sum_{i=1}^{k_1} (a_i+1),\sum_{i=k_1+1}^{k_2} (a_i+1), ..., \sum_{i=k_{l}+1}^n (a_i+1)\right\}\right\}_{k\in [n],l\in\mathbb{N}}?$$

I know that if you don't also consider the collection of terms with $a_i+1$, you can't distinguish $(1,2,1,3,2)$ and $(1,3,2,1,2)$. (For more information about the cases which can't be distinguished, see https://personal.math.ubc.ca/~steph/papers/elsarticle-weightedchrom.pdf)

As an example, if the list was $(1,2,1,3,2)$ I would be given the multisets $\{1,1,2,2,3\}$, $\{\{1,8\},\{2,7\},\{3,6\},\{4,5\}\}$, and $\{\{2,12\},\{3,11\},\{5,9\},\{7,7\}\}$. (You can distinguish which set you are looking at by looking at the sum of the terms, or the minimal elements.)

EDIT : Given just a single cut, Sil found a counter example with the two lists, (1,2,1,3,1,2) and (1,2,3,1,1,2).

  • Lists $(1,2,1,3,1,2)$ and $(1,2,3,1,1,2)$ both produce multisets ${{1,9},{3,7},{4,6},{3,7},{2,8}}$ and ${{2,14},{5,11},{7,9},{5,11},{3,13}}$. – Sil Mar 22 '23 at 09:31
  • Unfortunate, I'll rephrase the question to be about using the more general information. – Ishaan Shah Mar 22 '23 at 13:04
  • In your "any number of cuts"scenario are you assuming that $k_1,k_2,\dots,k_l$ are fixed? Or is the multiset somehow consisting of all possible cuts at the same time? Also it is unclear what you mean by $k \in [n]$ in that case. – Sil Mar 22 '23 at 17:06

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