Solve system of inequalities modulo












0












$begingroup$


Let $p in mathbb{N}$ be a composite number and let $x, y$ be vectors with elements from $mathbb{Z}_p$ of some fixed length (in my case it's 39). How to find such $k in mathbb{Z}_p$ that the value below is minimized?
$$
max(f(x + ky)))
$$

Here, $max$ is just maximum value of vector entries, while $f$ is the inclusion map from $mathbb{Z}_p$ to $mathbb{Z}$.



I'm looking for practical solutions. In my case $k = 39$ and $p = 311^2 cdot 313^2 cdot 317^2 cdot 331^2 cdot 337^2 cdot 347^2 cdot 349^2 cdot 353^2$. The brute force search over all values of $k$ is impossible.



Another version of the problem is as follows:



Given $0 leq nu < p$, find $k in mathbb{Z}_p$ such that
$$
max(f(x + ky))) < nu
$$



Is there any clever approach to any of the problems?



As an addendum, here's example on what exact function I want to minimize.
Let $p = 10$, $k = 3$. Here's example in Python:



p = 10
x = [4, 3, 8]
y = [1, 5, 0]
for v in range(p):
print(max([(e+v*f) % 10 for e, f in zip(x, y)]))


Output:



9 6 9 5 7 9 4 4 7 7


So here, we know that the minimum is at $v = 6$ or $v = 7$.










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$endgroup$












  • $begingroup$
    @Macavity no, that's just my sloppiness in the code (sorry)
    $endgroup$
    – enedil
    Dec 30 '18 at 2:04
















0












$begingroup$


Let $p in mathbb{N}$ be a composite number and let $x, y$ be vectors with elements from $mathbb{Z}_p$ of some fixed length (in my case it's 39). How to find such $k in mathbb{Z}_p$ that the value below is minimized?
$$
max(f(x + ky)))
$$

Here, $max$ is just maximum value of vector entries, while $f$ is the inclusion map from $mathbb{Z}_p$ to $mathbb{Z}$.



I'm looking for practical solutions. In my case $k = 39$ and $p = 311^2 cdot 313^2 cdot 317^2 cdot 331^2 cdot 337^2 cdot 347^2 cdot 349^2 cdot 353^2$. The brute force search over all values of $k$ is impossible.



Another version of the problem is as follows:



Given $0 leq nu < p$, find $k in mathbb{Z}_p$ such that
$$
max(f(x + ky))) < nu
$$



Is there any clever approach to any of the problems?



As an addendum, here's example on what exact function I want to minimize.
Let $p = 10$, $k = 3$. Here's example in Python:



p = 10
x = [4, 3, 8]
y = [1, 5, 0]
for v in range(p):
print(max([(e+v*f) % 10 for e, f in zip(x, y)]))


Output:



9 6 9 5 7 9 4 4 7 7


So here, we know that the minimum is at $v = 6$ or $v = 7$.










share|cite|improve this question











$endgroup$












  • $begingroup$
    @Macavity no, that's just my sloppiness in the code (sorry)
    $endgroup$
    – enedil
    Dec 30 '18 at 2:04














0












0








0





$begingroup$


Let $p in mathbb{N}$ be a composite number and let $x, y$ be vectors with elements from $mathbb{Z}_p$ of some fixed length (in my case it's 39). How to find such $k in mathbb{Z}_p$ that the value below is minimized?
$$
max(f(x + ky)))
$$

Here, $max$ is just maximum value of vector entries, while $f$ is the inclusion map from $mathbb{Z}_p$ to $mathbb{Z}$.



I'm looking for practical solutions. In my case $k = 39$ and $p = 311^2 cdot 313^2 cdot 317^2 cdot 331^2 cdot 337^2 cdot 347^2 cdot 349^2 cdot 353^2$. The brute force search over all values of $k$ is impossible.



Another version of the problem is as follows:



Given $0 leq nu < p$, find $k in mathbb{Z}_p$ such that
$$
max(f(x + ky))) < nu
$$



Is there any clever approach to any of the problems?



As an addendum, here's example on what exact function I want to minimize.
Let $p = 10$, $k = 3$. Here's example in Python:



p = 10
x = [4, 3, 8]
y = [1, 5, 0]
for v in range(p):
print(max([(e+v*f) % 10 for e, f in zip(x, y)]))


Output:



9 6 9 5 7 9 4 4 7 7


So here, we know that the minimum is at $v = 6$ or $v = 7$.










share|cite|improve this question











$endgroup$




Let $p in mathbb{N}$ be a composite number and let $x, y$ be vectors with elements from $mathbb{Z}_p$ of some fixed length (in my case it's 39). How to find such $k in mathbb{Z}_p$ that the value below is minimized?
$$
max(f(x + ky)))
$$

Here, $max$ is just maximum value of vector entries, while $f$ is the inclusion map from $mathbb{Z}_p$ to $mathbb{Z}$.



I'm looking for practical solutions. In my case $k = 39$ and $p = 311^2 cdot 313^2 cdot 317^2 cdot 331^2 cdot 337^2 cdot 347^2 cdot 349^2 cdot 353^2$. The brute force search over all values of $k$ is impossible.



Another version of the problem is as follows:



Given $0 leq nu < p$, find $k in mathbb{Z}_p$ such that
$$
max(f(x + ky))) < nu
$$



Is there any clever approach to any of the problems?



As an addendum, here's example on what exact function I want to minimize.
Let $p = 10$, $k = 3$. Here's example in Python:



p = 10
x = [4, 3, 8]
y = [1, 5, 0]
for v in range(p):
print(max([(e+v*f) % 10 for e, f in zip(x, y)]))


Output:



9 6 9 5 7 9 4 4 7 7


So here, we know that the minimum is at $v = 6$ or $v = 7$.







number-theory inequality modular-arithmetic nonlinear-optimization






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edited Dec 30 '18 at 2:03







enedil

















asked Dec 30 '18 at 0:02









enedilenedil

1,174619




1,174619












  • $begingroup$
    @Macavity no, that's just my sloppiness in the code (sorry)
    $endgroup$
    – enedil
    Dec 30 '18 at 2:04


















  • $begingroup$
    @Macavity no, that's just my sloppiness in the code (sorry)
    $endgroup$
    – enedil
    Dec 30 '18 at 2:04
















$begingroup$
@Macavity no, that's just my sloppiness in the code (sorry)
$endgroup$
– enedil
Dec 30 '18 at 2:04




$begingroup$
@Macavity no, that's just my sloppiness in the code (sorry)
$endgroup$
– enedil
Dec 30 '18 at 2:04










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