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An open problem that is widely regarded as one of the most important in quantum query complexity is to resolve the quantum query complexity of the k-distinctness function on inputs of size N. While the case of k=2 (also called Element…

Quantum Physics · Physics 2023-03-15 Nikhil S. Mande , Justin Thaler , Shuchen Zhu

We study the fundamental problem of clustering $n$ points into $K$ groups drawn from a mixture of isotropic Gaussians in $\mathbb{R}^d$. Specifically, we investigate the requisite minimal distance $\Delta$ between mean vectors to partially…

Statistics Theory · Mathematics 2026-02-27 Alexandra Carpentier , Nicolas Verzelen

In unitary property testing a quantum algorithm, also known as a tester, is given query access to a black-box unitary and has to decide whether it satisfies some property. We propose a new technique for proving lower bounds on the quantum…

Quantum Physics · Physics 2025-04-23 Jordi Weggemans

This paper initiates the study of quantum algorithms for matroid property problems. It is shown that quadratic quantum speedup is possible for the calculation problem of finding the girth or the number of circuits (bases, flats,…

Quantum Physics · Physics 2022-03-28 Xiaowei Huang , Jingquan Luo , Lvzhou Li

The $n$-qubit $k$-weight Dicke states $|D^n_k\rangle$, defined as the uniform superposition of all computational basis states with exactly $k$ qubits in state $|1\rangle$, form a basis of the symmetric subspace and represent an important…

Quantum Physics · Physics 2025-05-22 Pei Yuan , Shengyu Zhang

Quantum-inspired classical algorithms provide us with a new way to understand the computational power of quantum computers for practically-relevant problems, especially in machine learning. In the past several years, numerous efficient…

Quantum Physics · Physics 2025-01-15 Nikhil S. Mande , Changpeng Shao

Gap Hamming Distance is a well-studied problem in communication complexity, in which Alice and Bob have to decide whether the Hamming distance between their respective n-bit inputs is less than n/2-sqrt(n) or greater than n/2+sqrt(n). We…

Computational Complexity · Computer Science 2009-12-31 Joshua Brody , Amit Chakrabarti , Oded Regev , Thomas Vidick , Ronald de Wolf

We consider two combinatorial problems. The first we call "search with wildcards": given an unknown n-bit string x, and the ability to check whether any subset of the bits of x is equal to a provided query string, the goal is to output x.…

Quantum Physics · Physics 2014-07-16 Andris Ambainis , Ashley Montanaro

The polynomial method by Beals, Buhrman, Cleve, Mosca, and de Wolf (FOCS 1998, J. ACM 2001), the adversary method by Ambainis (STOC 2000, J. Comput. Syst. Sci. 2002), and the compressed oracle method by Zhandry (CRYPTO 2019) have been shown…

Quantum Physics · Physics 2025-10-27 Qisheng Wang , Zhicheng Zhang

A fundamental open problem in learning theory is to characterize the best-case teaching dimension $\operatorname{TS}_{\min}$ of a concept class $\mathcal{C}$ with finite VC dimension $d$. Resolving this problem will, in particular, settle…

Machine Learning · Statistics 2025-05-07 Spencer Compton , Chirag Pabbaraju , Nikita Zhivotovskiy

Local Search problem, which finds a local minimum of a black-box function on a given graph, is of both practical and theoretical importance to combinatorial optimization, complexity theory and many other areas in theoretical computer…

Quantum Physics · Physics 2007-05-23 Shengyu Zhang

We propose a new method for proving lower bounds on quantum query algorithms. Instead of a classical adversary that runs the algorithm with one input and then modifies the input, we use a quantum adversary that runs the algorithm with a…

Quantum Physics · Physics 2007-05-23 Andris Ambainis

We show how two recently developed quantum information theoretic tools can be applied to obtain lower bounds on quantum information complexity. We also develop new tools with potential for broader applicability, and use them to establish a…

Quantum Physics · Physics 2022-09-14 Ashwin Nayak , Dave Touchette

We give improved lower bounds for binary $3$-query locally correctable codes (3-LCCs) $C \colon \{0,1\}^k \rightarrow \{0,1\}^n$. Specifically, we prove: (1) If $C$ is a linear design 3-LCC, then $n \geq 2^{(1 - o(1))\sqrt{k} }$. A design…

Computational Complexity · Computer Science 2024-10-29 Pravesh K. Kothari , Peter Manohar

We study algorithms for solving three problems on strings. The first one is the Most Frequently String Search Problem. The problem is the following. Assume that we have a sequence of $n$ strings of length $k$. The problem is finding the…

Quantum Physics · Physics 2020-01-08 Kamil Khadiev , Artem Ilikaev

We prove a tight quantum query lower bound $\Omega(n^{k/(k+1)})$ for the problem of deciding whether there exist $k$ numbers among $n$ that sum up to a prescribed number, provided that the alphabet size is sufficiently large. This is an…

Quantum Physics · Physics 2012-08-13 Aleksandrs Belovs , Robert Spalek

We show that a large fraction of the data-structure lower bounds known today in fact follow by reduction from the communication complexity of lopsided (asymmetric) set disjointness. This includes lower bounds for: * high-dimensional…

Data Structures and Algorithms · Computer Science 2010-10-20 Mihai Patrascu

Simon's problem is one of the most important problems demonstrating the power of quantum computers, which achieves a large separation between quantum and classical query complexities. However, Simon's discussion on his problem was limited…

Quantum Physics · Physics 2017-01-04 Guangya Cai , Daowen Qiu

We develop a new technique for constructing sparse graphs that allow us to prove near-linear lower bounds on the round complexity of computing distances in the CONGEST model. Specifically, we show an $\widetilde{\Omega}(n)$ lower bound for…

Distributed, Parallel, and Cluster Computing · Computer Science 2016-05-18 Amir Abboud , Keren Censor-Hillel , Seri Khoury

Given a set of points, clustering consists of finding a partition of a point set into $k$ clusters such that the center to which a point is assigned is as close as possible. Most commonly, centers are points themselves, which leads to the…

Machine Learning · Computer Science 2023-10-16 Maria Sofia Bucarelli , Matilde Fjeldsø Larsen , Chris Schwiegelshohn , Mads Bech Toftrup