Computer Science Weekly Newsletter

Computer Science newsletter

Top new questions this week:

Are there any natural $\Pi_2^P$-complete problems?

I know that the quantified Boolean formula problem for a formula $$ \psi = \forall x_1 \ldots \forall x_n \exists y_1 \ldots \exists y_n \phi $$ where $\phi$ contains no quantifiers and only the ...

asked by vauge 8 votes
answered by Pål GD 9 votes

What type of algorithms are faster with a quantum computer?

I am a beginning CS student and I am learning algorithms. I heard that even with quantum computers, that general sorting algorithms can never have better than $n\log n$ time. However, I also know that ...

algorithms quantum-computing  
asked by user4485835 7 votes
answered by Luke Mathieson 7 votes

Efficient algorithm for this optimization problem? Dynamic programming?

I've created a diagram that depicts what I'm trying to accomplish. Full-size Image In the input sequence, the nodes are as close together as possible. But I want the white nodes to be as close to ...

algorithms dynamic-programming  
asked by FogleBird 7 votes
answered by Yuval Filmus 4 votes

Is there a complexity viewpoint of Galois' theorem?

Galois's theorem effectively says that one cannot express the roots of a polynomial of degree >= 5 using rational functions of coefficients and radicals - can't this be read to be saying that given a ...

complexity-theory np-complete np polynomials  
asked by user6818 7 votes
answered by Hurkyl 6 votes

PAC learning model definition

The probably approximately correct (PAC) learning model is defined as: A concept class $C$ is said to be PAC-learnable if there exists an algorithm $A$ and a polynomial function $poly(·,·,·,·)$ such ...

asked by Asterion 7 votes
answered by Yuval Filmus 5 votes

How do garbage collectors avoid stack overflow?

So I was thinking about how garbage collectors work and I thought of an interesting issue. Presumably garbage collectors have to traverse all structures in the same way. They can't know weather they ...

programming-languages memory-management garbage-collection  
asked by Jake 6 votes
answered by Gilles 6 votes

Relativization results in class separation

We know that $P\neq NP$ problem cannot be demonstrated by relativization because there exists oracle relative to which they are equal. Is there natural complexity classes that has been shown to be ...

asked by Turbo 6 votes
answered by Pål GD 3 votes

Greatest hits from previous weeks:

Heap - Give an $O(n \lg k)$ time algorithm to merge $k$ sorted lists into one sorted list

Most probably, this question is asked before. It's from CLRS (2nd Ed) problem 6.5-8 -- Give an $O(n \lg k)$ time algorithm to merge $k$ sorted lists into one sorted list, where $n$ is the total ...

algorithms algorithm-analysis heaps priority-queues  
asked by ramgorur 2 votes
answered by Dukeling 3 votes

Definition of the state of an object in OOP

I need a concise definition of the "state of an object" in object-oriented programming (for a paper). For about half of a day I searched for a paper that I can cite on this topic, but I couldn't find ...

terminology reference-request programming-languages object-oriented  
asked by mrsteve 5 votes
answered by Vor 6 votes

Can you answer these?

How do IR researchers evaluate the ranks of documents?

I am developing a new IR system in a specialized context. I understand that a traditional IR system (like a search engine) should rank documents in terms of their relevance for a query. The most ...

natural-lang-processing information-retrieval  
asked by bernie2436 2 votes

Oracle for an inverse function

A. Let $F$ be a monotonically increasing real function from $[0,1]$ onto $[0,1]$. Given an oracle to $F$ and a number $y$, is there a way to calculate the inverse function $F^{-1}(y)$ in a finite ...

asked by Erel Segal-Halevi 1 vote

Complexity of clustering lattice points

[Note] I have completely rewrited the question after Yuval's comments. I hope it makes more sense now! $\newcommand\ZZ{\mathbb Z}$$\newcommand\dist{\operatorname{dist}}$Consider the $d$-dimensional ...

algorithms reference-request computational-geometry  
asked by Bruno 4 votes
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