← Atlas

Algorithms · Quantum query algorithm

Matrix products over semirings

Compute the product of two n × n matrices over a semiring rather than a ring — the (max, min) product, the distance product, and the Boolean product — where the absence of subtraction rules out the fast algebraic algorithms that make ring matrix multiplication cost n^ω. The question the paper poses is whether anything beats the Õ(n^(5/2)) that follows from applying Grover search or quantum minimum-finding entry by entry.

Attested & literatureUpdated

View frozen graph

  • Record typeLiterature reference
  • Speedup class (secondary source)Polynomial
  • Primary source on the speedupStated by the primary source: "In comparison, the best known classical algorithm for the same problem, by Duan and Pettie (SODA'09), has complexity O(n^2.687)."
  • Reported costO(n^2.473) for the (max, min) product of two n × n matrices, against O(n^2.687) for the best known classical algorithm. For the distance product, the ℓ most significant bits of each entry are computed in O(2^(0.64ℓ) n^2.46). The sparse Boolean product is given as a four-case piecewise bound in the number of non-zero entries, and the paper says its algorithm performs better when n^1.151 < m < n^(ω−1/2).
  • Papers1

This record is not a concrete circuit.

References

  • Quantum Algorithms for Matrix Products over Semirings

    François Le Gall, Harumichi Nishimura · 2013

    Primary source, and the source of both the quantum and the classical figures this record compares. Consult it for the unit-cost oracle model of section 2 that every stated complexity depends on, for the generalized existence dominance product the reductions all pass through, and for the regime conditions attached to the distance-product and sparse Boolean results.

Attested & literature
  • Peer-reviewed paper
Method
Curation only. The problem statement was recorded from the literature; the speedup class is checked against the record's own primary paper, which states it; the primary reference's title, authors and submission year were read from its arXiv abs page; the complexity claim was taken from a clause of that paper's abstract (abstract of arXiv:1310.3898: "We construct a quantum algorithm computing the product of two n × n matrices over the (max, min) semiring with time complexity O(n^2.473)." and "We construct a quantum algorithm computing the ℓ most significant bits of each entry of the distance product of two n × n matrices in time O(2^0.64ℓ n^2.46)."; the classical figure is the abstract's own: "In comparison, the best known classical algorithm for the same problem, by Duan and Pettie (SODA'09), has complexity O(n^2.687)."; section 1 for the sparse regime: "Our algorithm performs better when n^1.151 < m < n^(ω−1/2)".). No circuit was constructed, simulated or run.
Result
Pass · the record's problem, speedup class and primary reference agree with the two sources named above.
Caveat
This is a literature record: nothing was constructed, compiled, simulated or run, and no matrix product was computed here. Every stated time complexity is in an oracle cost model that charges one unit per entry access — section 2 defines oracles that map |i⟩|j⟩|0⟩|z⟩ to |i⟩|j⟩|A[i,j]⟩|z⟩ and says the counting corresponds to the case where quantum access to the inputs can be done at unit cost, for example in a random access model working in quantum superposition. That is a quantum-RAM assumption, and the cost of providing it is not in these figures. The distance-product speedup applies to the ℓ most significant bits of each entry, not to the exact product: the proof assumes ℓ small enough that the bound stays below the trivial Õ(n^(5/2)), and full precision falls back to that trivial algorithm. The sparse Boolean improvement holds only inside the stated range of the number of non-zero entries. The paper is explicit that no speedup is offered for dense matrix multiplication over a ring, where it says quantum algorithms may not be able to outperform the classical Õ(n^ω). The classical figures quoted are the best algorithms known rather than proved lower bounds, and the paper notes that for the distance product no truly subcubic classical algorithm is known at all without assumptions, so the comparison there is against a weaker baseline than the exponents alone suggest.
Quantum Algorithms for Matrix Products over Semirings ↗
Kind
curated reference
Reviewed by
Leona Quantum curation pass
License
Citation metadata only; source publication terms apply
matrix multiplicationsemiringdistance productgrover searchquery complexity

Atlas stars stay in the public catalog. Saving this entry to your workspace starts an unstarred private copy.