Author: ignougroup

Problem Detail: Suppose one wanted to build a tree at random. Let the first insertion at step $i = 1$ be the root node. From here, nodes are inserted into the tree at random one at a time. How would one Read More …

Problem Detail: In the book “The New Turing Omnibus”, an excercise reads as the follows: “Show that no finite automaton can accept the language consisting of all words of the form $a^n b^n, n=1,2,3,…$ The formula represents $n$ a’s followed by Read More …

Problem Detail: Using the Earley vector as a recognizer is quite straightforward: when the end of the string is reached, you just have to check for a completed axiomatic production started at position 0. If you have at least one, then Read More …

Problem Detail: I use a variation of a 5-cross median filter on image data on a small embedded system, i.e. x x x x x The algorithm is really simple: read 5 unsigned integer values, get the highest 2, do some Read More …

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 …

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 …

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 …

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 …

Problem Detail: In studying logic to understand verifying programs I have found that there are books on logic targeted at Computer Science e.g. Logic in Computer Science: Modelling and Reasoning about Systems Mathematical Logic for Computer Science Computability and Logic Handbook Read More …

Problem Detail: Here’s something that has puzzled me lately, and perhaps someone can explain what I’m missing. Problems in NP are those that can be solved on a NDTM in polynomial time. Now assuming P$,neq,$NP, PSPACE$,neq,$NP etc. this means that there Read More …