All Questions
44,851
questions
2
votes
1
answer
34
views
What role does an asterisk serve in Backus–Naur Normal Form?
Suppose that you were reading some production rules for a context-free grammar in Backus–Naur Normal Form
What does the asterisk (*) mean?
In the example below, ...
- 149
0
votes
1
answer
16
views
How can we escape the pipe character in Backus–Naur Normal Form?
Suppose that you were writing down the syntax rules for something like C++ as a context-free grammar in Backus–Naur Normal Form
How can you distinguish between the pipe character as symbol in C++ or ...
- 149
0
votes
0
answers
17
views
What is an example of some production rules which would allow parentheses, curly braces, and square-brackets to be interchangeable?
In computer programming, there are many different ways to write a for-loop.
Some examples are shown below:
...
- 149
0
votes
0
answers
14
views
How to do signed 16-bit arithmetic on an 8-bit processor?
For example, to add two 16-bit numbers on my 8 bit machine, I add the low bytes together, then the high bytes together, and then add the carry flag to the high byte of the output.
This strategy falls ...
0
votes
0
answers
51
views
Find a range of values to subset the rows to maximize the objective function
I have searched around for some time but couldn't find a similar example to my problem.
It looks common enough that I would expect it to be solved. It lies between search and optimization/regression.
...
0
votes
0
answers
44
views
How to go about solving this induction?
The terms Lm and L′m for each natural number m are defined as follows. (Note that n and c are variables whereas m stands for a number or its Church encoding.)
...
Daisy Lambeth
0
votes
1
answer
20
views
How to find a crticial edge in a flow network?
The complete question is as follows:
An edge of a flow network is called critical if decreasing the
capacity of this edge results in a decrease in the maximum flow. Give
an efficient algorithm that ...
- 101
2
votes
0
answers
25
views
Create a Turing machine for this interactive game
Given two players $A, B$ and some natural number $n \ge 2$, let $\#(A,B,n)$ denote the following algorithm:
$A$ thinks of some number $a \in \{1,\ldots,n\}$
Until the game ends:
$B$ thinks of some ...
3
votes
2
answers
76
views
Rank in a Convex Combination
Given vectors $A, B \in \mathbb{R}^{n}$, $w \in [0,1]$ and $x \in \mathbb{R}$, let
$$
Rank(A,B,w,x)=\sum_{i=1}^{n} \boldsymbol 1 \{w A_{i} +(1-w) B_{i} < x\}
$$
denote the number of elements in the ...
0
votes
0
answers
44
views
What are optimizations that can be made after the type checker has completed?
So I am implementing a statically typed version of solidity.
I have a type checker built. I am working on User defined aliases currently.
...
0
votes
0
answers
76
views
What are Funges?
I am currently reading up about esoteric programming languages and came across a COS theory question stated as follows:
Esoteric programming languages can be categorised in a variety of different ...
- 1
0
votes
1
answer
47
views
Complexity of solving two different LP problems
I have one LP problem (LP1) to solve, where a term in a constraint is to be substituted after solving another LP problem (LP2) (with a different variable vector). Suppose I call the dimension of the ...
- 125
0
votes
1
answer
71
views
compute cache miss rate by given code
I have been trying to solve questions like this before but I have stumbled in difficulty to track the the space of the cache.
so there is an example of a question like this:
Given the code:
...
user152808
1
vote
1
answer
30
views
Is there a hypothesized "complete" class of problems between P and NP-hard?
For now, assume that P != NP. Is there a "complete" class of problems between P and NP-hard, and if so, what is it called? The two key words here are
between
complete
By between, I mean ...
- 453
0
votes
1
answer
39
views
Is this PDA correct or an erratum? (Sipser example 2.14)
I don’t understand this state diagram. What if $n=0$? Then our input string is the empty string. We begin at $q_1$, push \$ onto the string, move to $q_2$ but then fail. So the language recognized by ...
- 1
0
votes
0
answers
24
views
Why does it have that amount of stalls
I'm doing an exercise about the MIPS pipeline with the following characteristics:
-Branches and Branch targets are calculated in the E-stage.
-There is forward logic from the output to the input of ...
- 1
2
votes
1
answer
19
views
Strategy for searching for elementary cellular automata (cyclic boundary conditions) that repeat
I am looking for elementary cellular automata rules and initial conditions that give rise to interesting cycles (Cyclic boundary conditions, such that the leftmost entry is the neighbour of the ...
- 23
0
votes
0
answers
18
views
Help regarding evaluating the expression? [closed]
int main(int argc, char const *argv[])
{
int a = 1;
int b = (++a) + (a++);
cout << b;
return 0;
}
My approach :
...
- 1
0
votes
0
answers
14
views
Understanding heuristic function (Berkeley AI Project 1)
Cheers, I am playing around with Berkeley's AI Project 1 (Pacman) (link here) and I am trying to find a good heuristic function for the foodHeuristic function (Question 6).
While playing around with ...
4
votes
1
answer
89
views
Formal grammar of MIU system
The MIU system, famous from Douglas Hofstadter, is a semi-thue system with the following rules:
Xi → Xiu
mX → mXX
XiiiY → XuY
XuuY → XY
and a start axiom "mi"
I have tried to find a formal ...
- 143
0
votes
0
answers
14
views
Viterbi algorithm for object tracking
I want to solve a problem of object tracking along time. The problem is - I have a sequence of images, and I need to find and track the creation of the objects, than their movement, and than their ...
- 1
0
votes
0
answers
46
views
What are the methods to prove the correctness of an algorithm?
I want to know the major methods to prove the correctness of a program/algorithm. Recommendations on books are appreciated too. This is a general question. TIA.
Edit: I'm not looking to detailed ...
- 101
1
vote
1
answer
43
views
Turing machine read time
Suppose I have a Turing machine that takes as input any string of length $n$, where $n$ is odd, and the Turing machine returns the middle character of the string.
What time complexity class is this in?...
- 237
8
votes
3
answers
1k
views
Efficient sampling from all positive integers
Let's say we want to find the smallest positive integer x for which some property A holds. We know that such an integer exists. However, we have no knowledge about the scale of x (i.e. x could be 7 or ...
- 183
1
vote
1
answer
25
views
shortest path increases monotonically => a bound on the length of one iteration of Edmons-Karp is then O(E) ... Convince me this is true
I was reading the proof of time-complexity for the Edmonds-Karp algorithm here (https://brilliant.org/wiki/edmonds-karp-algorithm/).
Everything in the first part of the proof (The section ...
2
votes
3
answers
69
views
Algorithm that finds 4 "O"s or 4 "X"s on a diagonal, horizontal, or vertical
My algorithm homework revolves around matching 4 "O"'s or 4 "X"'s on a diagonal, horizontal, or vertical. ...
- 123
3
votes
1
answer
54
views
Given two strings ABC and CBA, find A, B and C
Given two strings ABC and CBA, find A, B and C.
Input:
abcacab, cabcaab
Output:
ab, ca, cab
The time complexity of brute force is O(n^3). Are there any better algorithms to solve this problem? Thanks!
- 31
0
votes
1
answer
20
views
Algorithms for finding closest graph node within set of nodes
Given a set of nodes $N$ on an undirected, weighted graph $G$ and a query node $n$, what is the fastest algorithm for finding the node in $N$ that is closest to $n$?
Furthermore, say we are doing many ...
0
votes
0
answers
13
views
Comparing two poses of a point cloud
I have an unstructured point cloud for which I determine pose information described as a similarity transform (rotation matrix and translation vector). In my setting, several independent poses are ...
- 4,601
-1
votes
1
answer
31
views
questions on set? [closed]
I am not able to understand this code, if we are using find() method and passing the value 'e' that means we are searching whether the element 'e' is present or not? After checking we can directly ...
-1
votes
0
answers
7
views
How do I show undecidability of this language using ALLCFG?
I used ALLCFG to show undecidability of EQCFG previously which was straightforward but the "or" condition in TRIVIALCFG is throwing me off. I don’t know a way to reduce TRIVIALCFG to ALLCFG.
- 1
0
votes
1
answer
28
views
Does a random phenomenon have a pre defined probability distribution? what does it mean for something to be random?
While studying Shannon's notion of perfect secrecy I came upon the idea that a bit is perfectly random if it happens to be 0 or 1 with an equal probability. What does this mean? Also, what can we say ...
- 3
0
votes
0
answers
14
views
What is the best SAIS algorithm implementation/variation as of now?
During the past few weeks, I have been learning about the SAIS algorithm and the different variations/implementations. Here is the most recent paper I have read: https://synergy.cs.vt.edu/pubs/papers/...
- 1
1
vote
1
answer
46
views
Data structure and optimal algorithm for modeling reachable outputs given a set of inputs
Given the following:
A set of input types $I$ = {a, b, d, ...}
A set of functions $F$ (With associated costs, and possibly identical signatures) = {($c_1$, a -> d), ($c_2$, (a,b) -> e), ($c_3$, ...
- 113
-2
votes
1
answer
29
views
Inversion array of a given array
Let A[1...n] be an array of n distinct numbers. The ordering of the numbers is any permutation of [1,2,...,n]. An array Inv_A is defined as follows: Inv_A[i] = number of elements A[j] such that j<i ...
1
vote
1
answer
35
views
Is the executable always loaded to the same place in the text segment?
I am reading a book about data architecture, and I am wondering about the text segment and the memory adresses.
In one example(assembly using ARM) where the code was compiled there were adresses to ...
- 111
1
vote
0
answers
27
views
Getting something wrong while building parse table for the grammar
Task
Build the Parse Table
Let $\mathcal{G}$ be the following context-free grammar:
$$
\begin{aligned}
E &\to TE' \\ E' &\to +TE'\; |\; \epsilon \\ T &\to F T' \; \\
T' &\to *FT'|\;\;\...
- 11
0
votes
0
answers
26
views
What is this standard of text display called?
I hope this is an appropriate site for this question. In the RINEX documentation http://acc.igs.org/misc/rinex304.pdf (RINEX is a file exchange format for GPS data), it gives an example of a RINEX ...
0
votes
0
answers
16
views
Is this Pumping Lemma proof correct? L = {{ca^ndb^m | n >= m >= 1}
Let L be = {ca^ndb^m | n >= m >= 1}
Let x be the word = ca^nd^m with |x|= 2n>=n. Look at x = uvw with |V|>=1 and |UV|<=n.
We have u= ca^kdb^k, v= b^l, w=b^m-k-l with |v| >= 1 and |uv|...
- 1
2
votes
1
answer
48
views
Are there any problems which are known to be both NP-complete and EXPTIME-complete?
Are there any problems which are known to be both NP-complete and EXPTIME-compelte? My guess is no, because we know that $P$ is not equal to $EXPTIME$ and EXPTIME-complete problems are not in $P$, ...
- 237
-3
votes
2
answers
66
views
Is frontend slang term is it used in teaching in univ
I have a question : is the term front-end in this context phpmyadmin is frontend for mysql slang is it taught in academy in this context I don't want to use slang term
3
votes
3
answers
94
views
Are there absolute reasons to prefer row/column-major memory ordering?
I've heard it said that "fortran uses column-major ordering because it's faster" but I'm not sure that's true. Certainly, matching column-major data to a column-major implementation will ...
- 143
0
votes
0
answers
38
views
Longest shortest path between two classes of nodes
(larger context at the end)
My view of the problem
I have an undirected graph whose nodes can be categorized into three classes depending on some metadata (I have a function that can tell me the class ...
- 101
-1
votes
2
answers
52
views
How to prove feasibility?
Let's say I have a optimization problem P1, where the constraints are linear but the objective function is not. Let's say I have another optimization problem which is linear in constraints and linear ...
- 101
0
votes
1
answer
22
views
2
votes
1
answer
35
views
Must the evaluation strategy for a language be specified in order to apply the Church-Rosser Theorem?
The Church-Rosser Theorem [0] states that the Lambda Calculus (LC) is
confluent: between a source expression S and target expression T, the
latter in normal form, for any given P, a sequence of ...
- 41
0
votes
0
answers
14
views
Canonicalizing Arbitrary EBNF Expressions
From what I understand, LL and LR parsing require a grammar to be in "canonical form", i.e. only productions of the form A -> b1 b2 ... bn, where ...
2
votes
1
answer
35
views
Is there a hierarchy of computational expressivity that is sensitive to evaluation strategies?
Various computational hierarchies describes the relative
expressivity of different classes of languages, machines, or other
models of computing, with the classic progression for Automata Theory
[0] ...
- 41
-1
votes
1
answer
16
views
Is there an algorithm able to finding the best cost in a graph that is weighted on both vertices and edges?
I have a problem that consists of finding a good solution for a graph that has vertex weights (and this cost is the highest priority), but also has edge costs.
- 1
-2
votes
0
answers
40
views
How to build an 4 bit width AND gate
I was trying to build an AND gate of 4 bit width. It doesn't work and I don't know how to fix it.
This is what I did. But the truth table is wrong.
How can I fix it? Thanx for the help.
