Problem Detail: I have two questions: I consider the following language $$L_1= { win {0,1}^* mid not exists uin {0,1}^* colon w= uu^R}.$$ In other words $w$ is not palindrome with even length. I proved that this language is NOT regular Read More …
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Calculating the Transfer Time for a Hard Disk
Problem Detail: I know that transfer rate is data size over transfer speed – but according to the information given, I don’t know what the data size is to calculate the transfer rate. Am I missing something or was I really Read More …
Why can’t we solve the Halting Problem by using Artificial Intelligence?
Problem Detail: Yesterday I was reading about Computability and they mention the Halting Problem. It got stuck in mind all day until I remember that some weeks ago, when learning Java, the IDE (Netbeans) show me a warning saying that my Read More …
Are regular and context free languages closed against making them prefix-free?
Problem Detail: For a language L we define: $qquad A(L) = { x in L mid text{ no proper prefix of x is in L} } $ Are regular / context free languages closed under this operation ? For regular languages Read More …
NP-Completeness of a Graph Coloring Problem
Problem Detail: Alternative Formulation I came up with an alternative formulation to the below problem. The alternative formulation is actually a special case of the problem bellow and uses bipartite graphs to describe the problem. However, I believe that the alternative Read More …
Finding recurrence when Master Theorem fails
Problem Detail: Following method is explained by my senior. I want to know whether I can use it in all cases or not. When I solve it manually, I come to same answer. $T(n)= 4T(n/2) + frac{n^2}{lg n}$ In above recurrence Read More …
Mapping Reductions to Complement of A$_{TM}$
Problem Detail: I have a general question about mapping reductions. I have seen several examples of reducing functions to $A_{TM}$ where $A_{TM} = {langle M, w rangle : text{ For } M text{ is a turing machine which accepts string } Read More …
How do I show that whether a PDA accepts some string ${ w!w mid w in { 0, 1 }^*}$ is undecidable?
Problem Detail: How do I show that the problem of deciding whether a PDA accepts some string of the form ${ w!w mid w in { 0, 1 }^*}$ is undecidable? I have tried to reduce this problem to another undecidable Read More …
How to measure “sortedness”
Problem Detail: I’m wondering if there is a standard way of measuring the “sortedness” of an array? Would an array which has the median number of possible inversions be considered maximally unsorted? By that I mean it’s basically as far as Read More …
How does Stack Inspection work?
Problem Detail: This is precursor to my other, more advanced question about Stack Inspection. Stack Inspection is a security mechanism introduced in the JVM to deal with running code originating from locations having different levels of trust. This is question aims Read More …
