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Main Authors: Bhattacharjee, Somnath, Kumar, Mrinal, Ramanathan, Varun, Saptharishi, Ramprasad, Saraf, Shubhangi
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2504.08063
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author Bhattacharjee, Somnath
Kumar, Mrinal
Ramanathan, Varun
Saptharishi, Ramprasad
Saraf, Shubhangi
author_facet Bhattacharjee, Somnath
Kumar, Mrinal
Ramanathan, Varun
Saptharishi, Ramprasad
Saraf, Shubhangi
contents While efficient randomized algorithms for factorization of polynomials given by algebraic circuits have been known for decades, obtaining an even slightly non-trivial deterministic algorithm for this problem has remained an open question of great interest. This is true even when the input algebraic circuit has additional structure, for instance, when it is a constant-depth circuit. Indeed, no efficient deterministic algorithms are known even for the seemingly easier problem of factoring sparse polynomials or even the problem of testing the irreducibility of sparse polynomials. In this work, we make progress on these questions: we design a deterministic algorithm that runs in subexponential time, and when given as input a constant-depth algebraic circuit $C$ over the field of rational numbers, it outputs algebraic circuits (of potentially unbounded depth) for all the irreducible factors of $C$, together with their multiplicities. In particular, we give the first subexponential time deterministic algorithm for factoring sparse polynomials. For our proofs, we rely on a finer understanding of the structure of power series roots of constant-depth circuits and the analysis of the Kabanets-Impagliazzo generator. In particular, we show that the Kabanets-Impagliazzo generator constructed using low-degree hard polynomials (explicitly constructed in the work of Limaye, Srinivasan & Tavenas) preserves not only the non-zeroness of small constant-depth circuits (as shown by Chou, Kumar & Solomon), but also their irreducibility and the irreducibility of their factors.
format Preprint
id arxiv_https___arxiv_org_abs_2504_08063
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Deterministic factorization of constant-depth algebraic circuits in subexponential time
Bhattacharjee, Somnath
Kumar, Mrinal
Ramanathan, Varun
Saptharishi, Ramprasad
Saraf, Shubhangi
Computational Complexity
Data Structures and Algorithms
While efficient randomized algorithms for factorization of polynomials given by algebraic circuits have been known for decades, obtaining an even slightly non-trivial deterministic algorithm for this problem has remained an open question of great interest. This is true even when the input algebraic circuit has additional structure, for instance, when it is a constant-depth circuit. Indeed, no efficient deterministic algorithms are known even for the seemingly easier problem of factoring sparse polynomials or even the problem of testing the irreducibility of sparse polynomials. In this work, we make progress on these questions: we design a deterministic algorithm that runs in subexponential time, and when given as input a constant-depth algebraic circuit $C$ over the field of rational numbers, it outputs algebraic circuits (of potentially unbounded depth) for all the irreducible factors of $C$, together with their multiplicities. In particular, we give the first subexponential time deterministic algorithm for factoring sparse polynomials. For our proofs, we rely on a finer understanding of the structure of power series roots of constant-depth circuits and the analysis of the Kabanets-Impagliazzo generator. In particular, we show that the Kabanets-Impagliazzo generator constructed using low-degree hard polynomials (explicitly constructed in the work of Limaye, Srinivasan & Tavenas) preserves not only the non-zeroness of small constant-depth circuits (as shown by Chou, Kumar & Solomon), but also their irreducibility and the irreducibility of their factors.
title Deterministic factorization of constant-depth algebraic circuits in subexponential time
topic Computational Complexity
Data Structures and Algorithms
url https://arxiv.org/abs/2504.08063