Problem Detail: Given a context-free grammar G, there exists a Nondeterministic Pushdown Automaton N that accepts exactly the language G accepts. (and visa versa) There may also exist a Deterministic Pushdown Automaton D that accepts exactly the language G accepts too. Read More …
Author: ignougroup
Dynamic programming table for finding similar substrings is too large
Problem Detail: Substring Diff Given two strings of length $n$, $P = p_1dots p_n$ and $Q = q_1 dots q_n$, we define $M(i, j, L)$ as the number of mismatches between $p_i dots p_{i+L-1}$ and $q_j dots q_{j+L-1}$. In set Read More …
Does cooperative scheduling suspend processes when they perform an I/O operation?
Problem Detail: Many operating systems references say that with cooperative (as opposed to preemptive) multitasking, a process keeps the CPU until it explicitly voluntarily suspends itself. If a running process performs an I/O request that cannot be immediately satisfied (e.g., requests Read More …
Automaton for substring matching
Problem Detail: Given $s$ as a string over some alphabet, what is the best known algorithm to compute a corresponding deterministic finite-state automaton (DFA) that accepts any string that contains $s$? I am mostly interested of the lowest time complexity so Read More …
Not able to convert from NFA to DFA
Problem Detail: I have a simple problem of making a DFA which accepts all inputs starting with double letters (aa, bb) or ending with double letters (aa, bb), given $Sigma ={a, b}$ is the alphabet set of the given language. I Read More …
Quantum lambda calculus
Problem Detail: Classically, there are 3 popular ways to think about computation: Turing machine, circuits, and lambda-calculus (I use this as a catch all for most functional views). All 3 have been fruitful ways to think about different types of problems, Read More …
Show $x^y$ is a primitive recursive function
Problem Detail: As this thread title gives away I need to prove $x^y$ to be a primitive recursive function. So mathematically speaking, I think the following are the recursion equations, well aware that I am assigning to $0^0$ the value $1$, Read More …
Designing a PDA w/o $epsilon$-moves and $leq 2$ states to accept an $epsilon$-free CFL by final state
Problem Detail: I understand that any CFL can be accepted by a PDA by final state or empty store but I have been rather stumped by this question. The question states that the PDA has at most 2 states. Clearly 1 Read More …
Retrieving data from hash table ordered by insertion time
Problem Detail: By default, a hash table is unordered. I have a simple question on the retrieval of elements in a hash table Can we retrieve elements from a hash table in the same order as they are put inside? Asked Read More …
Is it intuitive to see that finding a Hamiltonian path is not in P while finding Euler path is?
Problem Detail: I am not sure I see it. From what I understand, edges and vertices are complements for each other and it is quite surprising that this difference exists. Is there a good / quick / easy way to see Read More …
