Author: ignougroup

Problem Detail: Having trouble with this homework problem. In order to show that A is Turing recognizable and decidable. $text{EVEN} = text{binary strings with even length}$ $Let;A = {(M) | ,M; text{is a DFA such that L(M) is not the same Read More …

Problem Detail: Definitions According to my UML teacher formal means strictly according to rules, officially and how it’s supposed to be. He says a formal language = syntax + symbols + spelling. Another term he uses is deterministic. According to him Read More …

Problem Detail: Given the fact that $s$-$t$ path enumeration is a #P-complete problem, could there be efficient methods that compute (or at least approximate) the average length of $s$-$t$ path without enumerating them? What if paths are allowed to revisit vertices? Read More …

Problem Detail: I am studying algorithms from CLRS book. I try to understand the difference between probability of hiring the $i$th person out of $n$ and probability of hiring the $i$th person out of $n$ persons based on ranks. Using the Read More …

Problem Detail: I’m looking for an algorithm that provides a canonical string for a given colored graph. Ie. an algorithm that returns a string for a graph, such that two graphs get the same string if and only if they are Read More …

Problem Detail: COQ is an interactive theorem prover that uses the calculus of inductive constructions, i.e. it relies heavily on inductive types. Using those, discrete structures like natural numbers, rational numbers, graphs, grammars, semantics etc. are very concisely represented. However, since Read More …

Problem Detail: It was asked in an exam why a color video compress better than a black and white (grayscale) video using MPEG but can’t find anything explaining it. In other words, we would apparently get a better compression ratio when Read More …

Problem Detail: $L_1 = {a^mb^nc^{m+n}: n,m>1}$ I know $L_1$ is CFL and works with a pushdown automata. $L_2 = {a^nb^nc^{2n}: n>1}$ The language $L_2$ should also be a CFL because it looks similar, but in my book $L_2$ is not a Read More …

Problem Detail: I have that language $S={a^n b^m c^mmid n,m geq 0}$. How can I prove with the pumping lemma that it isn’t regular? Can I use the concatenation closure and say that it’s the language $L_1 = {a^nmid ngeq0}$ and Read More …

Problem Detail: Let $L = {a^n mid n ge 0}$, where $a^0 = epsilon$ and $a^n = a^{n-1}a$ for all $n ge 1$. Thus $L$ consists of sequences of $a$ of all lengths, including a sequence of length $0$. Let $L_2$ Read More …