Blog

Problem Detail: In class this week we’ve been learning about the CFLs and their closure properties. I’ve seen proofs for union, intersection and compliment but for reversal my lecturer just said its closed. I wanted to see the proof so I’ve Read More …

Problem Detail: Can someone help with this: $L={a^ib^j mid i,j ge 0 text{ and } i ne 2j}$ I’m trying to write a grammar for this language? I don’t know how to do this. I tried this: $S rightarrow aaAb mid Read More …

Problem Detail: I think it stores the address of the current instruction. And if this instruction is completed the program counter is incremented by 1, to get the next instruction. But now my question is, how do you increment the program Read More …

Problem Detail: I am currently bushing up on my data structures and basic algorithms, part of that is the Binary Tree. I do understand the algorithms, and how to implement a binary search tree and such. I do so how smart Read More …

Problem Detail: Say I want to find the n-th prime. Is there an algorithm to directly calculate it or must I do with sieving? I know always calculate the next prime with a sieve principle, but what if I want the Read More …

Problem Detail: I am having a little trouble understanding what is meant by a poly-time reduction. Suppose I have two algorithms $A$ and $B$ and then I say that $A$ is reducible to $B$. Does polytime reduction mean that the algorithm Read More …

Problem Detail: I am learning about context free languages. I understand how ${a^n b^n c^n | n ge 0}$ can be shown to be not context free using the pumping lemma for CFL’s. Intuitively however it seems that a pushdown automata Read More …

Problem Detail: I’m currently studying the book “Introduction to Algorithms – Cormen”. Although a proof of correctness for the BFS algorithm is given, there isn’t one any for the DFS in the book. So I was courious about how it can Read More …