All Questions
6 questions
0
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16
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Complexity of finding single source paths with capacity constraints and length constraints
Let $G=(V,A)$ be a directed graph with distinguished vertex $s\in V$ and let $c:A\rightarrow{\mathbb N}$ denote arc capacities. For any $t\in V,t\not=s$ we are given two numbers: $C_{t},L_{t}$. Let $...
1
vote
0
answers
51
views
Hardness of an optimization problem when some variables are fixed
Given a general optimization problem, I would like to know what we can say about the hardness of the problem when a subset of its variables are fixed.
With the two (related) examples, it is clear that ...
3
votes
1
answer
214
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NP-hardness of finding maximum of minimum element in diagonal of a matrix
For $A = \{a_{ij}\} \in R^{n\times n}$, is finding
$$
\max_{\sigma \in S_n}\min_{1 \le i \le n} a_{i,\ \sigma_i}
$$
NP-hard?
1
vote
0
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70
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Shortest Lattice Vector with restricted $x$
Let $\Lambda$ be a lattice with basis, $B$ consisting of vectors $b_i$, so that the elements of $\Lambda$ are of form, $y\in \Lambda \iff y=Bx=\sum_i b_ix_i$ for some $x_i\in\mathbb{Z}$.
My questions ...
16
votes
2
answers
603
views
NP-hardness of finding 0-1 vector to maximize rows of {-1, +1} matrix
Consider the following discrete optimization problem: given a collection of $m$-dimensional vectors $\{ v_1, \dots, v_n \}$ with entries in $\{-1, +1\}$, find an $m$-dimensional vector $x$ with ...
1
vote
0
answers
49
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Cost associated set problem NP-hard
I have the following problem. I wonder whether or not it appears in the literature. Is it NP-hard?
Given a set $S = \{1,2,\ldots,m\}$, and $A_1,\ldots, A_n$ are subsets of $S$. Each set $A_i$ has ...