Questions tagged [derandomization]
Every randomized algorithm can be simulated by a deterministic algorithm, at the expense of an exponential increase in running time. Derandomization is about converting randomized algorithms into efficient deterministic algorithms.
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Is BPP= P known for ANY uniform model of computation?
Many believe that BPP $=$ P "should" hold for Turing machines. We even have some "witnesses" for this: otherwise some "strange" things would happen; see e.g. this paper by Implagliazzo and Wigderson.
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Fine-grained complexity of BPP
If E does not have i.o.-$2^{o(n)}$ circuits, then P=BPP, but this does not tell us about the fine-grained containments between $\mathrm{Time}(n^a)$ and $\mathrm{BPTime}(n^b)$.
Are there reasonable ...
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Problem-Dependent Derandomization
The famous result of Impagliazzo and Wigderson in '97 cemented our belief that BPP is most likely the same as P; that is, problems that can be efficiently solved with randomness can also be ...
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Extensions of Affine Dispersers
A function $f\colon\{0,1\}^n\to\{0,1\}$ is called an affine disperser for dimension $d$, if for every affine subspace $S\subseteq \{0,1\}^n$ of dimension at least $d$, $f$ is not constant on $S$. This ...
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Extracting randomness from Santha-Vazirani sources using a seed of constant length
This question is actually an exercise problem from Salil Vadhan's draft survey "Pseudorandomness" marked with a star (*) (see Chapter 6, Problem 6.6). I do not know other references.
We say a random ...
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Deterministic approximation algorithms for treewidth
As far as I understand, the factor $O(\sqrt{\log OPT})$ approximation algorithm for treewidth of Feige, Hajiaghayi, and Lee is randomized, and no deterministic approximation algorithm with this factor ...
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On the shortest vector problem (is it $NP$-complete?)
Ajtai has shown that shortest vector problem is $NP$-hard by using randomized reduction from subset sum.
Has this been derandomized?
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Narrowing the gap between BPP and RP
We do not know yet whether the 2-sided error of $BPP$ allows more computing power than the one sided error of $RP$. In view of derandomization results, the conjectured answer is no, since both classes ...
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Physical Proof for P versus BPP
Lipton asks for a physical proof of $P\neq NP$.
Can we even ask for a physical proof for understanding $P=BPP$ or $P\neq BPP$? Is there anything in physics that lets us avoid randomness?
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Variation of (derandomized) Valiant-Vazirani
I am interested in the following "improvement" of the Valiant-Vazirani reduction. As pointed out here, under the right derandomization assumptions one can obtain a deterministic polynomial-...
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How is inapproximability by polynomial size circuits sufficient for the Nisan-Wigderson generator?
I couldn't understand how exactly Yao's XOR lemma was used to prove the following claim made in the proof of Theorem 2 of the original paper describing the Nisan-Wigderson generator, so I decided to ...
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On earlier references for $P=BPP$ and Kolmogorov's possible view on modern breakthroughs involving randomness?
Kolmogorov and Uspenskii in this paper 'http://epubs.siam.org/doi/pdf/10.1137/1132060' speculate P=BPP in 1986. They do this without getting into circuit lower bounds and from a different view which ...
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Randomized Parallel Algorithm for Maximal Independent Set
There are a couple of randomized parallel algorithms for the maximal independent set problem, e.g. A Simple Parallel Algorithm for the Maximal Independent Set Problem, A fast and simple randomized ...
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Concentration Bounds for Dependent Rounding
Consider the following random process which is defined on $n$ numbers $0\leq x_1,\ldots,x_n\leq 1$:
At each step, pick an arbitrary number, say $x_i$. Then randomly (and independently) change its ...
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Pseudodeterministically choosing elements from efficiently samplable distributions (or, the plausibility of a weak choice principle)
Suppose we have a poly-time samplable family of distribution. I.e., a family of distributions $D_n \subseteq \{0, 1\}^{\mathsf{poly}(n)}$ and an algorithm $S$ for which $D_n = (r \leftarrow^\$ \{0,1\}^...
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Does $P=BPP$ say anything about space complexity?
There are many streaming algorithms with sublinear randomized space but linear deterministic space. Does $P=BPP$ have anything to do with derandomizing space and more importantly but not related to ...
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Why are one way functions and pseudorandom number generators considered necessary or essential for derandomization?
If strong pseudorandom number generator exists then $BPP=P$ holds and if one way functions exists then $BPP\subseteq SUBEXP$ holds.
What are the best statements we have proved that come close to ...
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On approximating problems in $\#P$
We know that for every counting problem $\#A$ in $\#P$, there is a probabilistic algorithm
$\mathcal C$ that on input $x$, computes with high probability a value $v$ such that $$(1 − ε)\#A(x) ≤ v ≤ (1 ...
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Unique SAT and ETH
We know $ETH$ is a reasonable barrier to solving $SAT$ efficiently. We have $SAT$ reducing randomly to promise unique $SAT$ by $VV$. However we do not know if $VV$ can be derandomized. Given the ...
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How to improve this pseudorandom generator?
Let $f$ be a Boolean function and $\varepsilon > 0$.
There exists a pseudorandom generator $G_f: \{0,1 \}^{n^{\varepsilon}} \to \{0,1 \}^n$ with the following property.
Let $T$ be a set and $p(n)$...
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Does deterministic PIT produce deterministic irreducible polynomial generation?
In $\Bbb F_q[x]$ given $d\in\Bbb N$ there is a deterministic $O(poly(nd\log q))$ algorithm to find an irreducible polynomial with $d=deg(x)$ under $GRH$ and an unconditional randomized algorithm.
Do ...
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Scaled down and scaled up versions of Impagliazzo-Wigderson Therem
A famous theorem due to Impagliazzo and Wigderson states that if some function in $E=DTIME[2^{O(n)}]$ requires circuits of size $2^{\Omega(n)}$ then P=BPP.
When can we change $P$ with some ...
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Derandomization of Polynomial Identity Testing
There are some theorems that state $P = BPP$ if some condition is satisfied. For example, a theorem of Impagliazzo and Wigderson states tha $P=BPP$ unless $DTIME(2^{O(n)})$ has sub-exponential ...
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On $BPP$ in $P^{NP}$ and $SETH$
It is believed showing $BPP$ in $P$ involves good $PRG$s and faces lower bound barriers.
Does showing $BPP$ in $P^{NP}$ which would mean $BPP\neq EXP^{NP}$ face similar $PRG$ and give lower bounds?
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On $PP$ and derandomization
$PP\subseteq P/poly\implies PP=\Sigma_2\cap\Pi_2$ and $EXP\subseteq P/Poly\implies EXP=PP$ $=CH=MA$.
If $PP\subseteq P/poly$ then can $PP=\Sigma_2\cap\Pi_2=MA$ hold? Are there difficulties showing ...
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P=BPP and derandomizing Vazirani-Valiant?
Vazirani-Valiant reduction is a randomized reduction from $SAT$ to unambiguous $SAT$.
1. Is $P=BPP$ strong enough to derandomize Vazirani-Valiant reduction?
2. If not what other ingredients are ...
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Consequences of VP = VNP on randomness
According to the answers in posting it is possible that $\mathsf{VP} = \mathsf{VNP}$ and $\mathsf{P} \neq \mathsf{NP}$ are simultaneously correct.
$\mathsf{VP} = \mathsf{VNP}$ implies $\mathsf{P/...
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How to derandomize the Chernoff bound?
Avi Wigderson have a paper on how to derandomize the matrix-valued Chernoff bound. I would like to know whether there exists a simple version of paper on how to derandomize the real-valued Chernoff ...
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Amplifying success probability for PTMs with $poly(n) / \exp(n)$ gap?
The following is a well-known result of BPP in complexity theory, e.g., Theorem 1 and its proof from here:
Consider a probabilistic Turing Machine (PTM) $M$, and a language $L \in BPP$:
If $x \in L$ (...
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Non-uniform consequences of uniform derandomization
Adleman showed that $\mathsf{BPP/poly} \subseteq \mathsf{P/poly}$.
Does $\mathsf{P} = \mathsf{BPP}$ have any implications for
$\mathsf{BPP}/a(n) \subseteq \mathsf{P}/a(n)$
$\mathsf{BPTIME}(t(n))/a(n) ...
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