Computer Science Weekly Newsletter

Computer Science newsletter

Top new questions this week:

What exactly is computation?

I know what computation is in some vague sense (i.e. it's the thing computers do), but I would like a more rigorous definition.'s definitions of computation, computing, calculate, and ...

terminology computability  
asked by Kyth'Py1k 14 votes
answered by Yuval Filmus 5 votes

Algorithms for minimizing Moore automata

Brzozowski's algorithm can be extended to Moore automata but its time complexity is exponential in general. Is there any other algorithm for minimization of Moore automata? What are the running times ...

reference-request automata optimization finite-automata transducers  
asked by Ajeet Singh 7 votes
answered by babou 5 votes

Standard definition of Turing machine

I have followed two famous book on "Automata and Formal Language Theory": Micheal Sipser's book Jeffrey Ullman and John Hopcroft's book in both books, tuple level definition of Turing machine ...

terminology turing-machines  
asked by user3606704 7 votes
answered by Yuval Filmus 11 votes

A metaphor for recursive enumerability

In his commentary on a case involving pornography in 1964, U.S. Supreme Court Justice Potter Stewart sidestepped the question of defining what it meant for a work to be pornographic, but then said "I ...

computability didactics  
asked by Rick Decker 6 votes
answered by babou 4 votes

Is weighted XOR-SAT NP-hard?

Given $n$ boolean variables $x_1,\ldots,x_n$ each of which is assigned a positive cost $c_1,\ldots,c_n\in\mathbb{Z}_{>0}$ and a boolean function $f$ on these variables given in the form ...

optimization np-hard satisfiability integer-programming xor  
asked by Alexander Klauer 6 votes
answered by Yuval Filmus 7 votes

Given an array of size N, if you know that all of the elements are white except for one, how to find the index of that element efficiently?

Yesterday while returning home, I walked past a house that had a camera. For some reason I started thinking about how these cameras work, and how you would use them in case of robbery. While thinking ...

algorithms search-algorithms  
asked by jsguy 5 votes
answered by D.W. 7 votes

How to find a basis which is guaranteed to need 9 or less characters to represent a 12 digits number?

I'm trying to map a 12 digit number into a fixed width file. For a number of reasons, it must be compressed in such a way that it is guaranteed to be less than or equal to 9 characters (alpha numeric ...

databases encoding-scheme base-conversion  
asked by user34961 5 votes
answered by Kyle Jones 11 votes

Greatest hits from previous weeks:

Express boolean logic operations in zero-one integer linear programming (ILP)

I have an integer linear program (ILP) with some variables $x_i$ that are intended to represent boolean values. The $x_i$'s are constrained to be integers and to hold either 0 or 1 ($0 \le x_i \le ...

linear-programming integer-programming  
asked by D.W. 12 votes
answered by D.W. 17 votes

What determines the "speed" of a programming language?

Suppose a program was written in two distinct languages, let them be language X and language Y, if their compilers generate the same byte code, why I should use language X instead of the language Y? ...

programming-languages compilers  
asked by Rodrigo Araújo Valente 22 votes
answered by babou 14 votes

Can you answer these?

What are the strongest known type systems for which inference is decidable?

It's well known that Hindley-Milner type inference (the simply-typed $\lambda$-calculus with polymorphism) has decidable type inference: you can reconstruct principle types for any programs without ...

undecidability type-theory type-inference dependent-types  
asked by jmite 3 votes

For a given certain situation how to prove that the system will never get into the state of Deadlock

The situation is as follows 'm' process shares 'n' resources of same type. The maximum need of each process does not exceed 'n' and the sum all their maximum needs is always less than m+n. In ...

operating-systems concurrency deadlocks  
asked by Prateek 2 votes

Alpha beta algorithm with Iterative Deepening analysis

I'm implementing a chess engine. Like many engines, the search for the next best move is done with the alpha-beta algorithm. There are many improvements that can be made to make the algorithm faster ...

algorithm-analysis artificial-intelligence search-trees  
asked by Auberon 3 votes
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