Problem Detail: Consider a machine that has nested interrupts (a higher priority interrupt can interrupt a lower priority one, the current instruction’s address is saved and later restored). Why would a programmer want to disable all interrupts using instructions like x86’s Read More …
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[Solved]: NP completeness of closest vector problem
Problem Detail: Let $mathcal{B} = {v_1,v_2,ldots,v_k} in mathbb{R}^n$ be linearly independent vectors. Recall that the integer lattice of $mathcal{B}$ is the set $L(mathcal{B})$ of all linear combinations of elements of $mathcal{B}$ using only integers as coefficients. That is $$L(mathcal{B}) = { Read More …
[Solved]: When describing a CS paper, can it be assumed that the meaning of “tick” is known?
Problem Detail: I thinkt this question fits better here than on english.stackexchange. When describing a figure in a computer science paper, is it safe to use “tick” meaning “tick mark”? Examples: … (see the thick line right of tick “17”) meaning Read More …
[Solved]: Counting elements that are greater than the median of medians
Problem Detail: Short version: I want to know where the $-2$ comes from in the formula on p. 221 of CLRS 3rd edition. Long version: CLRS (3rd ed.) give an algorithm for $O(n)$ worst case arbitrary order statistic of $n$ distinct Read More …
[Solved]: Identifying an object in an image based on color (AI ?)
Problem Detail: First off, I am not sure if this is the correct stackexchange site to ask this question on, so moderators can feel free to move it. I am working on an application that identifies an object in an image. Read More …
[Solved]: randomized algorithm for checking the satisfiability of s-formulas, that outputs the correct answer with probability at least $frac{2}{3}$
Problem Detail: I’m trying to practice myself with random algorithms. Lets call a CNF formula over n variables s-formula if it is either unsatisable or it has at least $frac{2^n}{n^{10}}$ satisfying assignments. I would like your help with show a randomized Read More …
[Solved]: Language with $loglog n$ space complexity?
Problem Detail: We know that every non-regular language can be recognized with $ Omega (loglog n) $ space complexity. I’m looking for an example of a language which is $ Theta (loglog n) $ space complexity (if such exists). Asked By Read More …
[Solved]: Why are syntax trees used in genetic programming?
Problem Detail: Reading a course on genetic programming, the first chapter describes the syntax tree as the basic representation of programs in genetic programming. What are the reasons leading to the choice of a syntax tree in genetic programming? Are there Read More …
[Solved]: Can Euclidean TSP be exactly solved in time better than (sym)metric TSP?
Problem Detail: Symmetric/Metric TSP can be solved via the Held-Karp algorithm in $mathcal O(n^2 2^n)$. See A dynamic programming approach to sequencing problems by Michael Held and Richard M. Karp, 1962. In Exact Algorithms for NP-Hard Problems: A Survey (PDF) Woeginger Read More …
[Solved]: Maxima of diagonals in a column wise and row wise sorted matrix
Problem Detail: Let ${a_i}$ and ${b_i}$ be non-decreasing sequences of non-negative integers. How fast can one find $$c_j=max_{0 leq i< j}{a_i+b_{j-i-1}}$$ for all $0leq jleq n-1$? Naively, it takes $O(n^2)$ time, but I’m hoping monotonicity can help here. It’s easy to Read More …
