Quasi-linear Time Multiplication of Sparse Polynomials with Integer Coefficients
Pith reviewed 2026-06-27 07:45 UTC · model grok-4.3
The pith
A quasi-linear bit complexity algorithm for sparse polynomial multiplication with integer coefficients is obtained by reduction to modular black-box interpolation.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
By invoking the existing quasi-linear modular-black-box interpolation algorithm as a black box, the integer-coefficient sparse multiplication problem admits an algorithm whose bit complexity is quasi-linear in the combined size of the input and output.
What carries the argument
The modular-black-box interpolation algorithm, invoked as a black box to transfer its quasi-linear complexity to the integer-coefficient multiplication task.
If this is right
- The open challenge of quasi-linear output-sensitive sparse multiplication receives a solution for integer coefficients.
- For finite-field coefficients the bit complexity simplifies to linear dependence on the number of terms, the logarithm of the degree, and the logarithm of the field size.
- Any future improvement to the black-box interpolation routine immediately yields a corresponding improvement to the multiplication algorithm.
- The reduction shows that the integer-coefficient case can be handled without developing a new interpolation procedure from scratch.
Where Pith is reading between the lines
- Implementations in computer algebra systems could adopt the reduction once the underlying interpolation routine is available, potentially accelerating Gröbner-basis and resultant computations.
- The same black-box reduction strategy might apply to other coefficient domains that admit efficient modular reductions, such as algebraic number fields.
- If the interpolation routine itself admits a practical implementation, the multiplication algorithm could become the default method for large sparse products rather than a purely theoretical result.
Load-bearing premise
The modular-black-box interpolation procedure already runs in quasi-linear time when supplied as a black box.
What would settle it
An explicit input pair of sparse integer polynomials whose multiplication via the new algorithm requires super-quasi-linear bit operations would falsify the claim.
read the original abstract
Sparse polynomial multiplication is a fundamental problem in computer algebra and the theory of computation, and the development of a quasi-linear time output-sensitive multiplication algorithm has been posed as an open challenge. In this paper, a counterexample is provided to a previously claimed solution to this open problem for integer coefficients. By employing the existing quasi-linear modular-black-box interpolation algorithm, we are able to provide an algorithm with quasi-linear bit complexity for the integer coefficients setting. Furthermore, in the case of coefficients over a finite field, we obtain an algorithm whose bit complexity is linear in the number of terms, the logarithm of the degree, and the logarithm of the size of the finite field.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript provides a counterexample to a prior claimed quasi-linear time algorithm for sparse polynomial multiplication over the integers. It then constructs a new algorithm for the integer-coefficient case by reduction to an existing quasi-linear modular black-box interpolation procedure, claiming quasi-linear bit complexity overall. For coefficients in a finite field the claimed bit complexity is linear in the number of terms, the logarithm of the degree, and the logarithm of the field size.
Significance. If the counterexample is valid and the reduction to the black-box interpolator incurs only quasi-linear overhead, the result would supply the first output-sensitive quasi-linear bit-complexity algorithm for sparse polynomial multiplication over the integers, directly addressing the open challenge stated in the abstract.
major comments (2)
- [Abstract] Abstract (paragraph stating the counterexample): the manuscript asserts that a counterexample to the previously claimed solution is provided, yet neither the counterexample itself nor any verification or proof of its validity appears in the text, rendering the claim unverifiable from the given material.
- [Abstract] Abstract (paragraph describing the integer-coefficient algorithm): the claim that employing the existing quasi-linear modular-black-box interpolation algorithm yields quasi-linear bit complexity is load-bearing for the central result, but the text supplies no explicit complexity recurrence, bound on the number of black-box calls, cost of modular reductions, or analysis of lifting steps to confirm that these contribute at most quasi-linear factors.
Simulated Author's Rebuttal
We thank the referee for their careful reading and constructive comments. We address each major comment below.
read point-by-point responses
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Referee: [Abstract] Abstract (paragraph stating the counterexample): the manuscript asserts that a counterexample to the previously claimed solution is provided, yet neither the counterexample itself nor any verification or proof of its validity appears in the text, rendering the claim unverifiable from the given material.
Authors: We agree that the counterexample and its verification are not present in the manuscript text. In the revised version we will include the explicit counterexample together with a proof of its validity. revision: yes
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Referee: [Abstract] Abstract (paragraph describing the integer-coefficient algorithm): the claim that employing the existing quasi-linear modular-black-box interpolation algorithm yields quasi-linear bit complexity is load-bearing for the central result, but the text supplies no explicit complexity recurrence, bound on the number of black-box calls, cost of modular reductions, or analysis of lifting steps to confirm that these contribute at most quasi-linear factors.
Authors: We agree that an explicit complexity analysis is required. The revised manuscript will contain the complexity recurrence, bounds on the number of black-box calls, costs of the modular reductions, and analysis of the lifting steps demonstrating that the overhead remains quasi-linear. revision: yes
Circularity Check
No significant circularity; result is direct application of external black-box algorithm.
full rationale
The paper's central claim is that an algorithm with quasi-linear bit complexity for integer-coefficient sparse multiplication is obtained by employing an existing quasi-linear modular-black-box interpolation algorithm. The abstract presents this explicitly as an application of a pre-existing result without deriving the complexity bound from any fitted parameters, self-definitions, or load-bearing self-citations within the paper. The mention of a counterexample to a prior claim is separate and does not create a reduction. No equations or steps in the provided text reduce the claimed complexity to the paper's own inputs by construction. This qualifies as a self-contained application of independent external work.
Axiom & Free-Parameter Ledger
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