A quantum-inspired classical algorithm for recommendation systems
Open accessAbstract
We give a classical analogue to Kerenidis and Prakash’s quantum recommendation system, previously believed to be one of the strongest candidates for provably exponential speedups in quantum machine learning. Our main result is an algorithm that, given an m × n matrix in a data structure supporting certain ℓ2-norm sampling operations, outputs an ℓ2-norm sample from a rank-k approximation of that matrix in time O(poly(k)log(mn)), only polynomially slower than the quantum algorithm. As a consequence, Kerenidis and Prakash’s algorithm does not in fact give an exponential speedup over classical algorithms. Further, under strong input assumptions, the classical recommendation system resulting from our algorithm produces recommendations exponentially faster than previous classical systems, which run in time linear in m and n.
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Dequantization attempts have eliminated examples of speed-up for some problems in linear algebra.
“Such attempts have eliminated examples of speed-up for some problems in linear algebra.”
From Noisy intermediate-scale quantum algorithms (2022) · cites this paper as Tang, 2019
The Abstract (p. 1) says Tang’s classical algorithm shows that a quantum recommendation-system algorithm does not provide an exponential speedup; §1.1 (p. 2) describes the underlying task as sampling from a low-rank matrix approximation. This supports one linear-algebra-related example, but the paper does not establish that dequantization eliminated speedups for multiple problems, nor does it rule out smaller speedups. (LLM, conf=0.86)
Experimental — accuracy not yet measuredDequantized machine learning algorithms have been developed for recommendation systems, principal component analysis and supervised clustering, stochastic regression, and low-rank linear systems.
“So far, dequantized machine learning algorithms have been developed for recommendation systems (Tang, 2019), principal component analysis and supervised clustering (Tang, 2018), stochastic regression (Gilyén et al. , 2018) and low-rank linear systems (Arrazola et al. , 2019; Chia et al. , 2018).”
From Noisy intermediate-scale quantum algorithms (2022) · cites this paper as Tang, 2019
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Cites
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Noisy intermediate-scale quantum algorithms
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- Authors
- Tang, E.
- Affiliations
- The University of Texas at Austin (US)
- Corresponding author
- Tang, Ewin
- Venue
- Proceedings of the 51st Annual ACM SIGACT Symposium on Theory of Computing
- Publisher
- ACM
- Published
- 2019-06-23
- Pages
- 217-228
- OpenAlex
- W2880299821
- Cited by
- 360
- References
- 5
- Citations by year
- 2026: 48 · 2025: 35 · 2024: 36 · 2023: 47 · 2022: 48 · 2021: 52 · 2020: 67 · 2019: 20 · 2018: 6 · 2017: 1
- FWCI
- 17.89
- Type
- conference paper
- Language
- en
- Open access
- green
- arxiv.org
- Locations
- ACM Symposium on Theory of Computing (STOC) (publishedVersion)
- arXiv (Cornell University) (submittedVersion)
- Topics
- Physical Sciences › Computer Science › Artificial Intelligence › Quantum Computing Algorithms and Architecture
- Physical Sciences › Computer Science › Information Systems › Recommender Systems and Techniques
- Physical Sciences › Computer Science › Computational Theory and Mathematics › Complexity and Algorithms in Graphs
- Keywords
- recommender systems, quantum machine learning, quantum advantage
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