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For question borderline with, or having application to, computer science. Consider also posting http://cs.stackexchange.com/ or http://cstheory.stackexchange.com/ instead of here, if appropriate.

0 votes

Aren't "oracle machines" unsound concepts?

Oracles are used in complexity theory for lower and upper bounds in the decision tree model. Using oracles you can tell if the proof for certain problems (like P vs NP) relativizes or not. If it relat …
Marcos Villagra's user avatar
9 votes
3 answers
3k views

Complete problems for randomized complexity classes

It is believed that $BPP$ has no complete problems. Even for $BPP^O$ for a suitable oracle $O$ it is believed not to have complete problems, unless P=BPP. I wonder if the class MA (the randomized vers …
Marcos Villagra's user avatar
3 votes
2 answers
2k views

Practical use of probability amplification for randomized algorithms

Normally a 2-sided error randomized algorithm will have some constant error $\varepsilon < 1/2$. We know that we can replace the error term for any inverse polynomial. And the inverse polynomial can b …
Marcos Villagra's user avatar
7 votes

Problems known to be in both NP and coNP, but not known to be in P

A different nice example is a variant of the subset sum problem called Pigeonhole Subset Sum. Given $n$ positive integers with sum less than $2^n-1$, find two disjoint nonempty subsets whose sums are …
1 vote
1 answer
986 views

Number of subset sums

Let $\mathbb{F}_q$ be a finite field with characteristic $p$ and $p < q$ (i.e. not a prime field). Let $D\subseteq \mathbb{F}_q$ be a some set with $|D|=n$. Find a non-empty subset $\{x_1,\dots,x_k\} …
Marcos Villagra's user avatar