A Survey on Stacked Intelligent Metasurfaces: Fundamentals, Recent Advances, and Challenges

This survey provides a comprehensive overview of stacked intelligent metasurfaces (SIMs), detailing their physical principles, modeling frameworks, and hardware realizations while examining their role in enabling advanced 6G functionalities like wave-domain signal processing, integrated sensing, and cell-free networks, alongside identifying key challenges for future research.

Chandan Kumar Sheemar, Wali Ullah Khan, Sourabh Solanki, George C. Alexandropoulos, Symeon Chatzinotas2026-03-09🔢 math

Algebraic Invariants of Edge Ideals Under Suspension

This paper investigates how algebraic invariants of edge ideals change under selective graph suspensions, demonstrating that while suspensions over minimal vertex covers consistently preserve regularity and increase projective dimension by one, suspensions over maximal independent sets exhibit uniform behavior only for paths and cycles, with a specific extremal family of paths showing increases in both regularity and the a\mathfrak{a}-invariant.

Selvi Kara, Dalena Vien2026-03-09🔢 math

Graph labellings and external difference families

This paper establishes a systematic framework for constructing digraph-defined external difference families by combining graph blow-up techniques with generalized vertex labellings, resulting in new combinatorial families—including the first infinite construction for specific 2-circular external difference families—and novel results on graph labellings such as α\alpha-valuations for sun graphs.

Gavin Angus, Sophie Huczynska, Struan McCartney2026-03-09🔢 math

Color $2switchesandneighborhood-switches and neighborhood \lambdabalancedgraphswith-balanced graphs with k$ colors

This paper introduces color 2-switches to characterize kk-colored graphs with identical color degree matrices and defines several classes of neighborhood λ\lambda-balanced graphs to analyze their structural properties and minimum balance numbers across various graph families.

Karen L. Collins, Jonelle Hook, Cayla McBee, Ann N. Trenk2026-03-09🔢 math

FlexTrace: Exchangeable Randomized Trace Estimation for Matrix Functions

This paper introduces FlexTrace, a novel single-pass trace estimator that accurately computes the trace of matrix functions for large symmetric positive semi-definite matrices using only matrix-vector products with the original matrix, thereby overcoming the computational expense of existing methods that require products with the function of the matrix.

Madhusudan Madhavan, Alen Alexanderian, Arvind K. Saibaba2026-03-09🔢 math