Problem Detail: Data flow analysis work over a control flow graph. When a language under consideration supports exceptions, control flow graph can explode. What are the standard techniques for dealing with this blow-up? Can we soundly disregard edges induced by exception? Read More …
Category: Uncategorized
[Solved]: Is an irregular language concatenated with a language with which it has no common symbols irregular?
Problem Detail: Here’s an example of what I’m talking about. Suppose I have a languages $$ L_{1} = {a^ib^i mid i>0}, L_{2} = {c^i mid i>0} $$ and $$ L_{1}L_{2} = {a^ib^ic^i mid i>0} $$ Is it true that if $L_{1}$ Read More …
[Solved]: Bellman-Ford: shortest path
Problem Detail: my assumption: – we have an undirected graph with only positive edges – the edges are sorted alphabetically: e.g A-B, A-C, B-D and e.g not C-A, D-B, A-B I do not understand, why we need the first loop (line Read More …
[Solved]: Problems that are Cook-reducible to a problem in NP $cap$ co-NP
Problem Detail: Let $mathcal{A}$ be a problem in $text{NP} cap text{co}$-$text{NP}$. Now assume we can reduce another problem $mathcal{B}$ to it using Cook reduction. What conclusions can we draw about $mathcal{B}$? Does this question even make sense? I’m asking because from Read More …
[Solved]: Which NPC problems are NP Hard
Problem Detail: I have read that TSP and Subset Sum problems are NPC problems which are also NP Hard. There are also problems like Halting Problem which is NP Hard, but not NP Complete And Wikipedia defines this as A problem Read More …
[Solved]: Compute minimum hamming distance of a code
Problem Detail: How do you find the minimum hamming distance of a code? A naive way is computing the distance of each pair of codewords in our code. It becomes hard when the code is sufficiently large. Is there a formula Read More …
[Solved]: Random graph model
Problem Detail: When we say that in random graph we add an edge with a certain fixed probability, what do we actually mean? For example if probability is 0.5, does that mean that we can just add two edges in a Read More …
[Solved]: Connected Graph: Select the minimum number of nodes such that the node and neighbor covers everything
Problem Detail: The problem is to select the minimum number of nodes from a graph such that, the selected nodes and their neighbors consists of all the nodes of the graph. Any straight forward algorithm for this? Repeatedly selecting the node Read More …
[Solved]: What does $log^{O(1)}n$ mean?
Problem Detail: What does $log^{O(1)}n$ mean? I am aware of big-O notation, but this notation makes no sense to me. I can’t find anything about it either, because there is no way a search engine interprets this correctly. For a bit Read More …
[Solved]: PCA and Eigenvectors
Problem Detail: I am trying to understand how PCA works, and think I got most of it except… By calculating eigenvalues/vectors of the covariance matrix of the original dataset allows to find those dimensions where data is least correlated (lowest covariance). Read More …
