# Tagged Questions

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### Proving hardness of approximation with reduction in terms of 1/$\epsilon$

I have a reduction that proves that a problem is NP-hard to approximate to a factor $1 + \epsilon$ for any $0 < \epsilon < 1$. The reduction is polynomial in $n$ (the size of the instance of the ...
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### smallest circuit size using XOR gates

Suppose we are given a set of n boolean variables x_1,...,x_n and a set of m functions y_1...y_m where each y_i is the XOR of a (given) subset of these variables. The goal is to compute the minimum ...
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### How can I show that zero-one programming is not in APX?

How can I show that zero-one programming is not in APX? Vertex Cover Problem is in the APX class. So can I try a PTAS-reduction from the zero-one programming problem to Vertex Cover and show that ...
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### Calculating exact/approximate solution to a formula

Suppose we have a set of variable $\mathbf{y} = \left(y_1, ..., y_n \right)$. Also consider the set of functions $g_i(y_i), 1 \leq i \leq n$. Note that $g_i()$ is dependent only on $y_i$. Consider ...
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### Do there exist “odd times” cover problems and what do we know about their approximability?

I am currently investigating a problem which can be formulated as a cover problem, in which real intervals have to be covered an odd number of times by integers. My question is just, if anybody has ...
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### Minimize makespan on identical machines when jobs are vectors

Given are $n$ $d$-dimensional vectors and $m$ machines where $d$ need not be fixed. The objective is to minimize the makespan i.e., assign the vectors to machines such that the maximum of the ...
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### Greedy MAX SAT approximation ratio

Consider a naive MAX SAT approximation algorithm: pick a literal $l$ which appears in maximum number of clauses set the corresponding variable of $l$, such that all clauses containing $l$ are ...
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### Asymmetric metric TSP when many edges have equal costs in both directions

I would like to ask whether there exists a better approximation result on a special case of the ATSP metric instances: when cost(a,b)=cost(b,a) for $O(log(|E|)$ edges, or something close/related to ...
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### Approximating Max-Coverage when the elements need to be covered multiple times

In the set multicover problem we are given a set N of n elements and a set S of m subsets of N. Additionally, each element has a coverage requirement, i.e. the number of times it has to be covered. ...
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### Finding all-pairs anti-distance

Thanks for a great forum. This is my first post here. I am working on a signal processing application and the core of one the main algorithms reduces to a graph theoretical problem. Let $G=(V,E)$ ...
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