arXiv subjects

Abhibhav Garg

Publications and source records attributed to Abhibhav Garg.

8 recordsLinked to original sources

arXiv2026

An Improved Construction of Variety-Evasive Subspace Families

We study the question of explicitly constructing variety-evasive subspace families, a pseudorandom primitive introduced by Guo (Computational Complexity 2024) that generalizes both hitting sets and lossless rank condensers. Roughly speaking, a variety-evasive subspace family $\mathcal{H}$ is a collection of subspaces such that for every algebraic variety $V$ in a fixed family $\mathcal{F}$, there is some subspace $W \in \mathcal{H}$ that is in general position with respect to $V$. We give an explicit construction of a subspace families that evade all degree-$d$ varieties in an $n$-dimensional affine or projective space. Our construction improves on the size of the variety-evasive subspace families constructed by Guo and, for varieties of degree $n^{1 + Ω(1)}$, comes within a polynomial factor of Guo's lower bound on the size of any such variety-evasive subspace family. Our variety-evasive subspace families rely on an improved construction of hitting sets for Chow forms of algebraic varieties.

cs.CC↗

arXiv2026

Hilbert's Nullstellensatz is in the Counting Hierarchy

We show that Hilbert's Nullstellensatz, the problem of deciding if a system of multivariate polynomial equations has a solution in the algebraic closure of the underlying field, lies in the counting hierarchy. More generally, we show that the number of solutions to a system of equations can be computed in polynomial time with oracle access to the counting hierarchy. Our results hold in particular for polynomials with coefficients in either the rational numbers or a finite field. Previously, the best-known bounds on the complexities of these problems were PSPACE and FPSPACE, respectively. Our main technical contribution is the construction of a uniform family of constant-depth arithmetic circuits that compute the multivariate resultant.

cs.CC↗

arXiv2025

Rank Bounds and PIT for $Σ^3 ΠΣΠ^d$ circuits via a non-linear Edelstein-Kelly theorem

We prove a non-linear Edelstein-Kelly theorem for polynomials of constant degree, fully settling a stronger form of Conjecture 30 in Gupta (2014), and generalizing the main result of Peleg and Shpilka (STOC 2021) from quadratic polynomials to polynomials of any constant degree. As a consequence of our result, we obtain constant rank bounds for depth-4 circuits with top fanin 3 and constant bottom fanin (denoted $Σ^{3}ΠΣΠ^{d}$ circuits) which compute the zero polynomial. This settles a stronger form of Conjecture 1 in Gupta (2014) when $k=3$, for any constant degree bound; additionally this also makes progress on Conjecture 28 in Beecken, Mittmann, and Saxena (Information \& Computation, 2013). Our rank bounds, when combined with Theorem 2 in Beecken, Mittmann, and Saxena (Information \& Computation, 2013) yield the first deterministic, polynomial time PIT algorithm for $Σ^{3}ΠΣΠ^{d}$ circuits.

cs.CC↗

arXiv2025

Primes via Zeros: Interactive Proofs for Testing Primality of Natural Classes of Ideals

A central question in mathematics and computer science is the question of determining whether a given ideal $I$ is prime, which geometrically corresponds to the zero set of $I$, denoted $Z(I)$, being irreducible. The case of principal ideals (i.e., $m=1$) corresponds to the more familiar absolute irreducibility testing of polynomials, where the seminal work of (Kaltofen 1995) yields a randomized, polynomial time algorithm for this problem. However, when $m > 1$, the complexity of the primality testing problem seems much harder. The current best algorithms for this problem are only known to be in EXPSPACE. In this work, we significantly reduce the complexity-theoretic gap for the ideal primality testing problem for the important families of ideals $I$ (namely, radical ideals and equidimensional Cohen-Macaulay ideals). For these classes of ideals, assuming the Generalized Riemann Hypothesis, we show that primality testing lies in $Σ_3^p \cap Π_3^p$. This significantly improves the upper bound for these classes, approaching their lower bound, as the primality testing problem is coNP-hard for these classes of ideals. Another consequence of our results is that for equidimensional Cohen-Macaulay ideals, we get the first PSPACE algorithm for primality testing, exponentially improving the space and time complexity of prior known algorithms.

cs.CC↗

arXiv2025

An exposition of recent list-size bounds of FRS Codes

In the last year, there have been some remarkable improvements in the combinatorial list-size bounds of Folded Reed Solomon codes and multiplicity codes. Starting from the work on Kopparty, Ron-Zewi, Saraf and Wootters (SIAM J. Comput. 2023) (and subsequent simplifications due to Tamo (IEEE Trans. Inform. Theory 2024), we have had dramatic improvements in the list-size bounds of FRS codes due to Srivastava (SODA 2025) and Chen & Zhang (STOC 2025). In this note, we give a short exposition of these three results (Tamo, Srivastava and Chen-Zhang).

cs.CC↗

arXiv2022

Robust Radical Sylvester-Gallai Theorem for Quadratics

We prove a robust generalization of a Sylvester-Gallai type theorem for quadratic polynomials, generalizing the result in [S'20]. More precisely, given a parameter $0 < δ\leq 1$ and a finite collection $\mathcal{F}$ of irreducible and pairwise independent polynomials of degree at most 2, we say that $\mathcal{F}$ is a $(δ, 2)$-radical Sylvester-Gallai configuration if for any polynomial $F_i \in \mathcal{F}$, there exist $δ(|\mathcal{F}| -1)$ polynomials $F_j$ such that $|\mathrm{rad}(F_i, F_j) \cap \mathcal{F}| \geq 3$, that is, the radical of $F_i, F_j$ contains a third polynomial in the set. In this work, we prove that any $(δ, 2)$-radical Sylvester-Gallai configuration $\mathcal{F}$ must be of low dimension: that is $$\dim \mathrm{span}(\mathcal{F}) = \mathrm{poly}(1/δ).$$

cs.DM↗

arXiv2020

Special-case Algorithms for Blackbox Radical Membership, Nullstellensatz and Transcendence Degree

Radical membership testing, and the special case of Hilbert's Nullstellensatz (HN), is a fundamental computational algebra problem. It is NP-hard; and has a famous PSPACE algorithm due to effective Nullstellensatz bounds. We identify a useful case of these problems where practical algorithms, and improved bounds, could be given, when the transcendence degree $r$ of the input polynomials is smaller than the number of variables $n$. If $d$ is the degree bound on the input polynomials, then we solve radical membership (even if input polynomials are blackboxes) in around $d^r$ time. The prior best was $> d^n$ time (always, $d^n\ge d^r$). Also, we significantly improve effective Nullstellensatz degree-bound, when $r\ll n$. Structurally, our proof shows that these problems reduce to the case of $r+1$ polynomials of transcendence degree $\ge r$. This input instance (corresponding to none or a unique annihilator) is at the core of HN's hardness. Our proof methods invoke basic algebraic-geometry.

cs.CC↗

arXiv2018

Technical Report on the CleverHans v2.1.0 Adversarial Examples Library

CleverHans is a software library that provides standardized reference implementations of adversarial example construction techniques and adversarial training. The library may be used to develop more robust machine learning models and to provide standardized benchmarks of models' performance in the adversarial setting. Benchmarks constructed without a standardized implementation of adversarial example construction are not comparable to each other, because a good result may indicate a robust model or it may merely indicate a weak implementation of the adversarial example construction procedure. This technical report is structured as follows. Section 1 provides an overview of adversarial examples in machine learning and of the CleverHans software. Section 2 presents the core functionalities of the library: namely the attacks based on adversarial examples and defenses to improve the robustness of machine learning models to these attacks. Section 3 describes how to report benchmark results using the library. Section 4 describes the versioning system.

cs.LG↗