The two-week focus workshop took place in July 2025 and included six international guests, among them master's students, postdocs, and experienced professors.

We studied the so-called tensor rank, a specific complexity measure from linear algebra that applies to tensors, i.e., generalizations of matrices. Our focus was on tensors that are Kronecker powers of fixed small tensors. The structure of such tensors resembles Sierpinski triangles or tetrahedra.

The relevance of Kronecker powers and their ranks has been known in algebraic complexity theory for some time, especially in the context of theoretical algorithms for matrix multiplication. Recent years have shown that the connections extend further into computer science, especially into efficient algorithms for set partitioning and graph coloring. 

In this workshop, we strengthened these connections and discovered new ones. The workshop was funded by the ERC Starting Grant COUNTHOM.