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For questions about construction and modification of matrices, objects represented by 2-dimensional arrays that are used to define linear operators within linear algebra.

0 votes

Conditional Maximization of a Binary Matrix

There is a solution with something like $\tilde{O}(L!)$ complexity. Enumerate all permutations of the $L$ rows. Consider one such permutation, and permute the rows accordingly. Then apply the follow …
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0 votes

Is there a way to confirm a matrix multiplication solution in O(n)

Yes, Freivald's algorithm meets all of your requirements.
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1 vote

Given a $n \times n$ matrix $M$ find a subset of d rows and d columns so that the sum of the...

It is NP-hard, by reduction from the maximum balanced biclique problem. Suppose you have a bipartite graph $G$, and the goal is to test whether there is a balanced biclique of size $d$. Let $M$ denot …
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1 vote

Mathematical operation for removing duplicate rows in a matrix

A more efficient approach is to hash each row, insert them into a hash table, and find duplicates in that way. The running time will be $O(n^2)$. You can implement something like this using only line …
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2 votes

Learning eigenvalue decomposition

This smells like an XY problem. A neural network is not a good tool to use for computing the eigenvalue decomposition. Machine learning is best for problems where you have examples of input-output p …
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3 votes

Generate paths of fixed length across a weighted matrix (defined in $\mathbb{R}$) whose weig...

You're right. It is a sort of 0-1 knapsack problem. It is NP-complete in general. So you will need to settle for approximate solutions or heuristics or algorithms that only work for short strings o …
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1 vote
Accepted

Selecting a submatrix of a binary matrix NP hard?

Your problem is NP-hard. In particular, it is equivalent to maximum edge weight biclique problem (MWBP), which is known to be NP-hard. Maximum edge weight biclique MWBP is the following problem: give …
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1 vote

Writing an Algorithm to Represent a Bit Matrix in Minimal Operations?

I believe the problem is NP-hard, even with only set(), and is even hard to approximate within a factor better than 2. See https://mathoverflow.net/q/105164/37212, https://cstheory.stackexchange.com/ …
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1 vote

Having a 2D matrix with three typed elements, how to efficiently cover one of the types and ...

This looks very hard to me. I wouldn't be surprised if it is NP-hard. If I had to solve it in practice, my first thought would be to try to solve it using a SAT solver or an ILP solver. I outline be …
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1 vote
Accepted

Finding a map between two matrices that minimises distance differences of neighbors

I expect that solving the problem exactly might be NP-hard. However, here is an approach that I expect will probably be good enough for practical purposes. It uses a subroutine to solve the following …
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1 vote

Data structure to efficiently add zero-rows to a sparse matrix

You can achieve $O(\log n)$ time for all operations, by using a balanced binary search tree for the index that maps from a row index to the row. Such a tree can support $O(\log n)$ time lookup of any …
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2 votes

A hash function for a 2D hash table with a scattering property?

A random bijective function should satisfy this property with high probability for any specific set of indices. So, I suggest you use a random bijection on $[n^2]$. If $n$ is very large, you can comp …
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1 vote

Lower bound on number of zero columns in matrix

(Both matrices are in reduced row echelon form, so both are valid inputs.) However this algorithm will output the same thing for both inputs. Hence this algorithm cannot be correct. …
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0 votes
Accepted

Matrix rank only adding single row

I will assume the original matrix has $n-1$ rows, $n$ columns, and the rows are linearly independent (this is easy to check; and if it is not the case, then the problem is trivial). Adding a new row $ …
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3 votes

Finding a boolean submatrix isomorphic to a specific fixed set of other boolean matrices

The problem is NP-hard; it is at least as hard as the biclique problem. If you can solve the problem for a single shaped box, you can solve for all boxes by just iterating over all the boxes. So your …
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