Problem Detail: I just started a course called ‘Automata and Formal Languages’. I’m having difficulty in proofingdisproofing this equality. $ (L_{1} circ L_{2})^{+} = L_{1}^{+} circ L_{2}^{+} $ Where: $ L_{1} $, $L_{2}$ are Languages. $circ$ is the concatenation operation between Read More …
Category: Uncategorized
Image pattern detection – Finding similarities in same image
Problem Detail: The problem: Only pattern-like images are supposed to be uploaded and be used as backgrounds to a site, photos should not. How would you detect if an image looks enough like itself to be regarded as a pattern? Asked Read More …
What is the purpose of M:N (Hybrid) threading?
Problem Detail: In other words, what advantages does Hybrid threading have over 1:1 (kernel only) and N:1 (user only) threading? This is a follow-up to What is the difference between user-level threads and kernel-level threads? Asked By : Sheldon Answered By : svick Read More …
I can not see why MSD radix sort is theoretically as efficient as LSD radix sort
Problem Detail: Here is the pseudocode for LSD radix sort from http://www.cs.princeton.edu/~rs/AlgsDS07/18RadixSort.pdf public static void lsd(String[] a) { int N = a.length; int W = a[0].length; for (int d = W-1; d >=0; d–) { int[] count = new int[R]; for(int Read More …
Chromatic polynomial of a square
Problem Detail: Consider a square, ABCD. Intuitively it seemed to me that its chromatic polynomial is $lambda(lambda – 1)(lambda – 1)(lambda – 2)$ where there are $lambda$ colours available.. That is there are $lambda$ ways in which a colour for A Read More …
Using coloring optimization or coloring decision to solve coloring search
Problem Detail: How can you show that coloring search can be solved by making a polynomial number of calls to the solution for coloring optimization or coloring decision? (Coloring search is the algorithm to color the vertices of a graph such Read More …
Is it possible that the halting problem is solvable for all input except the machine’s code?
Problem Detail: This question occurred to me about the halting problem and I couldn’t find a good answer online, wondering if someone can help. Is it possible that the halting problem is decidable for any TM on any input so long Read More …
Minimum space needed to sort a stream of integers
Problem Detail: This question has gotten a lot of attention on SO: Sorting 1 million 8-digit numbers in 1MB of RAM The problem is to sort a stream of 1 million 8-digit numbers (integers in the range $[0,: 99mathord{,}999mathord{,}999]$) using only Read More …
Operator precedence in propositional logic
Problem Detail: there is some kind of priorities for the elements in propositional logic ? for example : p ∧¬q → r , given this ,we there may be two options (p ∧¬q) → r OR p ∧ (¬q → r) Read More …
Computing the mode of XOR subsequences
Problem Detail: I was confronted with this problem in an online programming challenge and it has been bugging me since: In the problem, you are given a list of 16-bit numbers, say $a_0, a_1, …, a_n$. An “XOR subsequence” is defined Read More …
