The Power of Shallow-depth Toffoli and Qudit Quantum Circuits

This paper establishes new separations between shallow-depth quantum circuits (specifically those with quantum advice or Toffoli gates with mid-circuit measurements) and classical constant-depth circuits, while also demonstrating that infinite-size gate sets in QNC0\mathsf{QNC}^0 can implement threshold gates and that higher-dimensional qudit circuits offer no advantage over standard qubit implementations in this regime.

Alex Bredariol Grilo, Elham Kashefi, Damian Markham, Michael de OliveiraThu, 12 Ma⚛️ quant-ph

The Generation-Recognition Asymmetry: Six Dimensions of a Fundamental Divide in Formal Language Theory

This paper proposes a unified framework for the generation-recognition asymmetry in formal language theory by identifying six distinct dimensions of divergence, challenging the oversimplified view that generation is inherently easy while parsing is hard, and exploring the implications of these operational differences for fields ranging from compiler design to large language models.

Romain PeyrichouThu, 12 Ma💬 cs.CL

Classical simulability of quantum circuits followed by sparse classical post-processing

This paper establishes a necessary and sufficient condition for the classical simulability of polynomial-size quantum circuits followed by sparse classical post-processing and demonstrates that constant-depth variants of such circuits can be efficiently simulated by a probabilistic algorithm using commuting quantum circuits with bounded gate complexity.

Yasuhiro Takahashi, Masayuki Miyamoto, Noboru KunihiroMon, 09 Ma⚛️ quant-ph

Why Are Linear RNNs More Parallelizable?

This paper establishes a theoretical foundation for the superior parallelizability of linear RNNs by demonstrating that they correspond to log-depth arithmetic circuits (NC1\mathsf{NC}^1-complete), whereas nonlinear RNNs are fundamentally limited by their ability to solve L\mathsf{L}- and P\mathsf{P}-complete problems, thereby explaining why linear variants can be efficiently parallelized like transformers while traditional nonlinear RNNs cannot.

William Merrill, Hongjian Jiang, Yanhong Li + 2 more2026-03-06💻 cs

Classification of Local Optimization Problems in Directed Cycles

This paper presents a complete classification of the distributed computational complexity for local optimization problems in directed cycles within both deterministic and randomized LOCAL models, identifying four distinct complexity classes and providing an efficient meta-algorithm to automatically determine the complexity and synthesize optimal distributed algorithms for any given problem.

Thomas Boudier, Fabian Kuhn, Augusto Modanese + 2 more2026-03-06💻 cs

A $4/3$ ratio approximation algorithm for the Tree Augmentation Problem by deferred local-ratio and climbing

This paper introduces a novel "deferred local-ratio" technique to present a $4/3approximationalgorithmfortheTreeAugmentationProblemthatrunsin-approximation algorithm for the Tree Augmentation Problem that runs in O(m\sqrt{n})$ time, offering a faster alternative to existing state-of-the-art methods without relying on complex enumeration or LP rounding.

Guy Kortsarz2026-03-06💻 cs

On complexity of restricted fragments of Decision DNNF

This paper investigates the complexity of restricted fragments of Decision DNNF, specifically d\wedge_d-OBDD and Structured Decision DNNF, by establishing lower bounds for CNFs of bounded incidence treewidth, demonstrating exponential separations between various models, identifying efficient cases for the Apply operation, and introducing a relaxed model called Structured d\wedge_d-FBDD that effectively handles CNFs of bounded incidence treewidth.

Andrea Calí, Igor Razgon2026-03-06💻 cs