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 ...

complexity-classes  
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 ...

machine-learning  
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 ...

complexity-theory  
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 ...

time-complexity  
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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