Category: Uncategorized

Problem Detail: I’m trying to make a turing machine that will take in a binary string as input x and output the binary representation of the length of x. So M(0110) returns 100, M(1010101010) returns 1010, ect. It also has to Read More …

Problem Detail: Is there an NP complete language having no polytime decidable superset (apart from the set of all strings)? Asked By : ARi Answered By : David Richerby No, assuming P$,neq,$NP. Let $L$ be any NP-complete language over alphabet $Sigma$ and let $N Read More …

Problem Detail: My intuition is telling me that this is untrue. But I am having trouble formulating a proof for this. Can anyone point me in the right direction? I’ve seen a proof by contradiction involving the union of all singletons Read More …

Problem Detail: Let $T$ be a Turing machine whose accepted language is $L(T)$. Let $X$ be another language. How do you approach a proof like $L(T)subseteq X?$ Asked By : And Answered By : Hendrik Jan In order to prove that any machine, Read More …

Problem Detail: I asked a (seed) question about sums of Landau terms before, trying to gauge the dangers of abusing asymptotics notation in arithmetics, with mixed success. Now, over here our recurrence guru JeffE does essentially this: $qquad displaystyle sum_{i=1}^n Thetaleft(frac{1}{i}right) Read More …

Problem Detail: Consider the following grammar with starting symbol of $S$. $$S rightarrow 0S11;|;S1;|;0$$ Let $L = {0^i1^j:; ge 1; and; j ge2i-2}$ . Give a formal proof of the following claim : For all $n;ge0$, every string of length $n$ Read More …

Problem Detail: is there any difference between transition systems and finite automata? Is it that transition systems consist of both NFA (nondeterministic finite automata) and DFA (deterministic finite automata)? Asked By : ishaarora95 Answered By : Luke Mathieson Yes, did you try wikipedia? Read More …

Problem Detail: I’m enrolled to a Formal Language And Automata course, and we have to prove this equation on sets of strings: $$(L_1cap L_2)cdot L_3 ≠ (L_1cdot L_3) cap (L_2cdot L_3)$$ I’ve tried a lot of sets for e.g. $L1 = Read More …

Problem Detail: Every undecidable problem that I know of falls into one of the following categories: Problems that are undecidable because of diagonalization (indirect self-reference). These problems, like the halting problem, are undecidable because you could use a purported decider for Read More …

Problem Detail: Given a word list of $N$ words formed from a language of $M$ characters, where each word is composed of $n geq 1$ not necessarily distinct characters, how can I find the best set of $k<M$ characters to learn, Read More …