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This is a branch that includes: computational complexity theory; complexity classes, NP-completeness and other completeness concepts; oracle analogues of complexity classes; complexity-theoretic computational models; regular languages; context-free languages; Komolgorov Complexity and so on.

1 vote
0 answers
104 views

Simultaneous elimination of variables in multiple polynomials

I have a system of $n=O(1)$ non-homogeneous polynomials of total degree $d=O(1)$ $p_1,\dots,p_r\in \mathbb Z[x_1,\dots,x_n]$. I would like to eliminate $n-1$ variables simultaneously from the $n$ poly …
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1 vote
0 answers
88 views

Proof for non-existence of short integer program for squares

We do not know if $P=NP$ or not or if there is a superfast integer mutiplication algorithm. But I do not think either assumption is necessary to answer this question. Is there a way to show within an …
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2 votes
0 answers
90 views

Why cannot we adapt Barvinok type counting techniques to general convex integer programs?

Decision problems in Integer Linear Programming have Lenstra type algorithms (https://www.math.leidenuniv.nl/~lenstrahw/PUBLICATIONS/1983i/art.pdf) have been generalized to convex integer program tech …
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3 votes
1 answer
328 views

Nonexistence of short integer program sequence which generates squares

Is there a way to show within an integer program with constant number of variables and constraints of length $poly(\log B)$ (say length $\leq10^{1000000}\log B$), it is not possible for a variable to …
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3 votes
1 answer
272 views

On shortest vector problem

Assume we have an oracle which gives the length of the shortest vector in a lattice. Given this oracle can we find the shortest vector in polynomial time?
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1 vote
0 answers
34 views

Does $2$ variable linear Diophantine equation in $NC$ imply $2$ dimensional shortest vector ...

Consider the Linear Diophantine in known $a,b,c\in\mathbb Z$ $$ax+by=c.$$ Above can be solve by Extended Euclidean which is not in $NC$ as far as we know. It is clear if Extended Euclidean is in $NC$ …
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1 vote
0 answers
101 views

On determinant and permanent of certain homotopy defined simple matrices

Let $A_1,A_2,B_1,B_2$ be four $n\times n$ $0/1$ square matrices where $$\det(A_1)=\det(A_2)=per(A_1)=per(A_2)=1$$ $$\det(B_1)=\det(B_2)=per(B_1)=per(B_2)=0$$ hold ($per$ refers to permanent). I. What …
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1 vote
0 answers
161 views

On an optimization question

Suppose we have a square matrix $M=(1-z)A+zB$ where $A,B$ have integer entries from $\{0,1\}$ with $\det(A)+\det(B)=1$ and $\det(A),\det(B),per(A),per(B)\in\{0,1\}$ and we want to find $z\in[0,1]$ tha …
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2 votes
0 answers
214 views

Modular inverse computation - avoiding Euclidean algorithm

Modular inverse is known to be computable by Extended Euclidean algorithm which is the reaping the rewards of computing the GCD of two numbers or proving two numbers are coprime. If we already know t …
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0 votes
0 answers
121 views

Will an integer program to deterministically factor integers help derandomize $\mathbb F_q[x...

There are many analogies between the objects $\mathbb F_q[x]$ and $\mathbb Z$. Supposing there is a fixed (say $10^9$) dimension linear integer program (describable without any objective function) in …
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2 votes
1 answer
476 views

Modular square roots problem which is $NP$ hard

It is well known extracting modular square roots modulo a composite number factors the modulus. On other hand given $u,v>0$ and an integer $n$, deciding if there is a factor of $n$ in $[u,v]$ is $NP$ …
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1 vote
0 answers
69 views

Is this factorization problem in EXP?

Factorization is not known to have a polynomial time algorithm. Traditionally the input length is number of bits in representation of the integer to be factored. However now consider integers of form …
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2 votes
0 answers
197 views

On GCD and lattice reduction

$LLL$ algorithm is vectorized version of Euclidean algorithm for $GCD$. Even the $m=2$ case known to Lagrange and Gauss does not have an $NC$ algorithm for shortest vector. If $GCD$ is in $NC$ and in …
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4 votes
0 answers
104 views

Questions in number theory related to $NC$ and $P$-completeness

Given $a,b\in\mathbb N$ find $\operatorname{GCD}(a,b)$. Given $a,b,c\in\mathbb N$ find $x,y\in\mathbb Z$ such that $ax+by=c$. Euclidean algorithm solves both. My question is if either 1 or 2 is i …
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2 votes
1 answer
171 views

On roots of irreducible quadratics modulo composites

Assume factorization of $N$ is unknown. What is the best complexity we know to find roots of the irreducible equation $$ax^2+bx+c\equiv0\bmod N?$$ Is this problem equivalent to any hardness results?
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